Cultivation and breeding oftomato

Dr. P. Hanson

(4)

-L TOMATO PRODUCTION AND TRENDS

World and Asian Production of Selected Vegetables, 1994

Crop World Asia

(1000 MT)Tomato 77540 27430Onion 32546 17735CNk+Gpepper ]1192 5414Cucumbers 19261 13465Cabbage 40250 22299

Source: FAO Production Yearbook, 1994

Tomato Production Area Trends in Selected Asian Countries

1979-81 1994 change

Area (1000 ha) 0/0

China 238 344 +443India 167 321 +48.0Indonesia 23 48 +I09.0Philippines 16 13 -18.8

Source: FAO Production Yearbook, 1994

2. MARKET TYPES

Fresh Market

- tomato sold in the markets for eating raw or for cooking- preferences vary among countries:

Taiwanese like green-shouldered tomatoes with slight reddening on the blossom-end, whilemany Japanese consumers prefer pink-colored tomatoes; most people prefer deep red coloredtomatoes

- size and shape preferences vary among countries

Processing Tomato (PT)

- tomato type used to produce paste, sauce, whole-peeled tomato, catsup or other pi-oducts- deep red color, pH <4.5, high solids content, viscosity important for PT- plant type is usually determinant, with short vines,- some PT varieties can be harvested by machine

Cherry Tomato (Lycopersicon esa&mtimnr cerasifoame)

- small-sized tomato (<30 grams)

ill OF TOMATO

Vitamin Content of Selected Raw Vegetables(100g edible portion)

VegetableVit.A

(IU)

Thiamine Ribo-flavin(Ing)

Niacin

(mg)

AscorbicAcid(mg)

TomatoOnionSweet pepperEggplantCarrotCommon cabbageChinese cabbageBroccoliKaleSweet potato

1133 0.06 0.05 0.60 17.60 0.06 0.01 0.10 8.4

530 0.09 0.05 0.55 128.070 0.09 0.02 0.60 1.6

28129 0.10 0.06 0.93 9.3126 0.05 0.03 0.30 47.3

1200 0.04 0.05 0.40 27.01542 0.07 0.12 0.64 93.28900 0.11. 0.13 1.00 120.0

20063 0.07; 0.15 0.67 22.7

Source: Knott's Handbook for Vegetable Growers, 1988.

4. ORIGIN AND DOMESTICATION OF TOMATO

- tomato Lycopersicon esculentum is a self-pollinating crop with up to 4% outcrossing

- Lycopersicon species have a haploid chromosome number of 12 and are diploids

- Western side of the Andes mountains is the center of diversity of the genus Lycopersicon

- L. esculenturn var. cerasiforr .e (cherry tomato) is the probable ancestor of the cultivated tomato

- World-wide dispersal of tomato by the Spanish after the 15th century

5. GROWTH HABIT

- there are 2 growth habits in tomato: determinate and indeterminate

Determinate

- determinate: growing point in the axil of the last formed leaf on the primary shoot transformsinto a flower and no more leaves are initiated

- determinates have about 5 flower clusters, each cluster developing about 5-7 fruit

- there are usually 2 leaves between clustersdeterminate habit conditioned by a single recessive allele called spsemi-determinates have 6 or more clusters with two leaves bewteen clusters

Indeterminate

- indeterminate habit: continuous extension of the main shoot by side shoots. The terminal buddoes not set fruit but produces more leaves and stem from the growing tipinflorescences are formed after every 3 leaves

- indeterminate habit conditioned by a single dominant allele called sp +

Bacterial Wilt

- symptoms:drooping of lower leaves, wilting, no yellowing, bacterial ooze

- the major disease of tomato common in warm wet conditions- causal organism used to be called Psetidoiimiias solaiiacmmm. The genus name was recently

changed to Btirkliolderia

- P. solanacearuin. classified into 5biovara(based on utilization of disaccharides and. alcohols) and5 races (host range)

- wide host range

The major sources of bacterial wilt resistance are derived from these sources:

- (originallyVenus/Saturn from L. I)hiipinellifoliuln [1124080)

- [RA 66 (landrace from the French West Indies)- L. p/my6vdDfo/ o/x II 127805A from which Hawaii 7996, Hawaii 7997

'

Kevvalm/vvene derived.Considering the importance of bacterial wilt, the number of different resistance sources is small.

Fusarium wilt

symptoms:- [oUaryellowing, discoloration of outer vascular system- caused by Fusariuin oxys porn in f. lycopersici, a soil-borne fungus- 3knovvnraces: races l8r2xze common; race 3 has been found in Australia and Florida- Resistance genes are called I, 1-2,1-3; I and. 1-2 are commonly found in many hybrids and lines

Late Blight

' caused by Phytophthora hijestaiis- symptoms include indefinite water-soaked lesions which enlarge and become pale-green or

brown; sometimes ag7ayisb-vvldLeo)oldckclenthe lesion- favored by cool (18-22 OC) wet conditions- races identified: TO, T1; race Ti is common in the n- Resistance genes: Ph, Ph- 2- Widespread distribution of Al and A2 mating types may allow sexual reproduction of the

fungus

Nematodes

- IvIeloidogyne incognita, M. javanica, 8&ormuria are nematode species common in the tropics; M.incognita is the most prevalent

- Migone (from L.pumviamwni) gives resistance to &eloidoynuspecies but Mi is reported not tobe effective at temperatures above 28 OCA new nematode resistance gene, m.0, was recentlyreported

Tobacco Mosaic Virus

- mechanically transmitted and very common- symptoms: mottled areas of light and dark gmen on the leaves and leaves may be curled, stunted- Dominant genes for resistance include Izo-1, Tm-2; the Tm-2

aallele provides resistance to all

known TK4Vstrains

Gemini Viruses

- Gemini viruses found world-wide in various forms with different names; Tomato Yellow LeafCurl Virus is a c used name

- symptoms: yellow foliage, mosaic, curling, stunting- virus gen000ehas 1 or 2 circular single-stranded [>N&molecules- virus transmitted by the vvhiteUy(7eVfis/mVrgextifo/fi)- symptoms appear about 15 days after whitefly feeding

Gemini Virus Resistance- L. chiiense has highest levels of resistance- Ty-1, a semi-dominant allele for TYLCV tolerance from L. cifilo8Ge has been introgressed into

tomato /Zazuiret al, 1994)-

a number of hybrids resistant/ tolerant togenuini viruses have been released, including 'Fiona'

7. INSECT PESTS

(a caterpillar with prominent rows of dark bumps, tu-bercles, on its back) is the major insect pmblem of tomato in the tropics although others such as

(Bemisia argentifolii) vectors &mini virus and can cause foliar damage also. Tomato growers have

~er^^~de~heavily ---pesticides ----insect control. However, populationsinsectinsecticides have developed and coosozneze. in many countries am demanding resistant to somevegetables withless pesticide residues. Breeding for insect resistance is increasing. Introgression of insect resis-tance from the wild tomato species such as L. pnnne//d (LA 716), and L. I/rxutu/n (especially LA1777), is an active area of research (Eigenbrode and Ironible,l993).

8. ABIOg IC PESTS

High Temperature Fruit Set

Optimum temperatures for toozahoare about 25"r

daytime teoznecatnzeaaudl5-20~

[ouioinuoztemperaures. Minimum temperatures >21 OC may cause poor fruit set in oncue tomato varietiesand can result from poor pollen development, lack of anther debi ceoceoxoLberpnoblezna. SomeAVRDC tomato lines set fruit in ouidzoouzLeozperatuoeoof 25

-

Csuch as [L5915-93D4-1-O-3. Fruitset without seed-set is called parthenocarpy

Flooding

Flooding is common in the tropics, especially in the summer season. Two types of damage occur:displacement oxygen from soil pore spaces with water and rain impact on the above ground plantparts. Flooded plants show epinasty, wilting, and often die if flooded for longer than three days

9. FRUIT QUALITIES

Deep Globe GlobeSquare

Oblate Deep Oblate

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Firmness

pericarp firmness is very important in countries where production areas are far from markets.This character is a quantitative trait controlled by several genes.

Color

Fruit color is usually measured by a color differential meter. Immature green tomatoes have an a/b ratio less than 0 and the ratio increases as fruit ripens toward a full dark red.

Lycopene, a carotenoid, is formed during fruit ripening and it determines the degree of fruit red-ness. Lycopene synthesis is inhibited at temperatures greater than 30 C. Beta carotene, the otherprincipal tomato carotenoid, is the precursor of vitamin A. Its synthesis is not so sensitive to hightemperature. Several genes (hp, B, t, r, og, dp) affect fruit color as well as vitamin Acontent of thefruit. Genes hp and dg increase total carotenoid content and increase vitamin A. The B gene in-creases beta-carotene content at the expense of lycopene causing fruit to be orange-yellow col-ored. The genes ogc (crimson gene), r (causes yellow fruit color and almost eliminates carotenes),and t (tangerine gene) reduce vitamin A content. The gene og C deepens the red fruit color butdecreases vitamin A content.

Acidity (% citrate)

Most acid in the fruit is contained in the locu.les. Fruit pH varies from 4-5 in L. esculenturn.. A pHless than 4.5 is important for processing tomato. Citrate is the major fruit acid.

AVRDC tests for acidity (% citrate) in the following manner: 5 ml tomato juice is dilutes with 40 mldistilled water, and the dilution is titrated with alkali solution (0.05 N NaOH) to pH 8.1

Acidity = titrate volume (ml) x 0.05 N NaOH x 192 g/mole x 1/3 x loosample (ml) x 1000

192 g/mole is the molecular weight of citrateValence of citrate= 3

Solids ()brix)

Tomato fruit is 94-95% water and 5-6% organic compounds (solids). The solids is comprised ofvarious components: Sugars (fructose, glucose, sucrose which are found primarily in the fruitwall) make up about 50% of the solids; pectins, cellulose, proteins, polysaccharide (alcohol in-soluble solids) compose 25% of the solids; organic acids such as citrate and malate make-up 12%of the solids, and the remainder of the solids consists of carotenoids, volatile compounds, aminoacids, and inorganic compounds.

A high solids content is important for processing, especially for tomato paste. Environmentalfactors such as irrigation, soil texture, disease resistance etc. affect solids content. Generally, yieldand solids content show a negative relationship. (Higher yield, lower % solids). Indeterminategrowth habit favors a higher solids content. Them appears to be a high correlation between %solids and juice viscosity and firmness.

% Solids is measured by placing a few drops of juice on the prism of a refractometer and readingthe percent soluble solids

Taste

The secret of good tomato taste is difficult to pin down and a high solids content, sugar and acidconcentrations, and aromatic compounds contribute to good taste.

Fruit disorders

Graywall: black-brown necrotic areas in the fruit wall and usually develops on green fruit. Thedisorder is thought to be related to potassium nutrition. Some varieties are more inclined to de-velop than others

Cat-face: misshapen fruit with large scars and holes in the blossom end. Cold weather; high Nnutrition increase chances of cat-facing

Blossom-end rot: black, leathery lesions on. the fruit blossom end (end not attached to the stern).Elongated fruit are more susceptible to blossom end rot. Calcium deficiency, high ammonium Nfertilizer, water supply flucuations, high relative humidities can lead to blossom end rot

Cracking: radial and concentric

Puffiness: cavities in the fruit locu.l.es . Caused by poor seed set, which in turn can be caused byinadequate pollination, fertilization, or seed development.

Persistent yellow shoulder is caused by slow chlorophyll break down in high temperatures

6

PRODUCTION OF .Fi HYBRID SEEDS IN TOMATO

Romeo T. Opena & Jen-tzu Chen

Asian Vegetable Research & Development Center

Introduction

The advent of commercial hybrid seeds in cross-pollinated crops like maize has led to phenomenal

improvements of yield and quality. The concept has caught on as well in the self-pollinated specieseven though the evidences on heterozygote advantage ("heterosis") among them have not been

unequivocal. Nowadays, it is not uncommon to find F1 hybrid varieties of self-pollinated crops,

particularly vegetables, released as commercial cultivars. Tomatoes rank as one of the most popular

vegetables for which hybrid varieties have been developed and released to growers, often by

private seed companies, but sometimes also by public agencies.

Self-pollinated species do not have the mechanisms of hybridity which facilitate hybridization in

cross-pollinated crops, viz. self-incompatibility, male sterility, dioecy, etc.. Therefore, hybrid seed

production is manually done. This process takes invariably many hours of skilled work. Hybrid

seed production in these crops has thus become a special technology requiring close attention to

many important details. Any miscues in the process usually translate to reduced seed quality and

often rejection of seed lots.

This guide sheet (which normally goes with a slide set) was prepared to provide basic guidelines

in the production- of F l hybrid seeds of tomatoes. Some aspects described herein are location-

specific. Users of this guide sheet should have enterprising spirits to modify and/or devise new

ways to carry out specific tasks. Ingenuity is often rewarded through increased efficiency and

productivity.

Evolution and General Types Qf Tomato.

Tomato belongs to the genus Lycopersicon of the family Solanaceae. The genus is generally believed

to have originated in the narrow west coast area of South America, ranging from Ecuador to

Chile, between the Andes Mountain and the sea. Only L. cheesemanii which is found mainly in the

Galapagos Islands is found elsewhere. The

primitive genetic materials of L. esculents in (var. cerasiforme) was further domesticated in Mexico.

From here, tomatoes was introduced into the Old World (Europe) from where it was distributed

worldwide in different times.

Two main types of tomatoes may be distinguished based on growth habit viz. determinate type

(or simply "bush" type) and indeterminate type The bush type cultivars are widely grown for

either fresh consumption or for processing into canned tomatoes, puree, soup, juice or ketchup.

The indeterminate cultivars are grown mainly for fresh consumption. Very rarely are they grown

for processing as the processing industry has relied increasingly on high volume production over

1

a short time span, a trait that was impossible select and breed from indeterminately growing

genotypes. Modern processing cultivars are suitable for mechanical harvest (once-over harvest),

have the firmness of f r uit necessary to withstand rough handling by machine, and have the required

processing quality, viz. high soluble solids and good color.

Horticultural Requirement for Seed Production

The general horticultural requirements of tomatoes may be taken from the accompanying guide

sheet. It is important that materials for seed production be given the optimum conditions forgrowth and reproduction to insure that good seed quality and high overall seed yield will be

attained in any seed production scheme. Other books and references on production of tomatoes

may also be consulted. In the end, many of the production techniques are location-specific andshould not be taken literally in the process. They should, in other words, be modified if necessary

to fit the local growing conditions.

Procedures of Hybrid Seed Production

The production of good quality hybrid seeds of tomatoes does not just require the best condition,

viz. cool, dry clin`ate, for seed production. Of equal if not greater importance are several technical

aspects that one must pay attention to in order to insure success. Below a number of technical

issues to consider are given and elaborated. Some of them might require modifications under

local conditions and should be viewed as general guidelines in seed production.

Ratio of maternal to paternal plants. It is important that there is an adequate source of pollen

during pollination. For this reason, sufficient male plants producing good flowers at the right

time should be assured. Tomatoes flower profusely and normally, a ratio of 4 female to 1 maleplants is adequate. This ratio may be adjusted according to the flowering behavior of the pi+rents.

A ratio of 5:1 is sometimes used.

Sowing time. The male parent should be sown ahead of time, usually 7-10 days before the female

parent, but could be as long as three weeks earlier depending upon flowering time. In so doing, an

adequate source of pollen is available at pollination time.

Planting. At AVRDC, it is a common practice to plant the female line at a spacing of 60 cm between

rows in a two-row raised bed system and 50 cm between hills. On the other hand, the male pa rent

is planted at a spacing of 150 cm between rows (single raised bed system) and 40 cm between hi I Is.

The male parent plants are ordinarily planted in a different place to avoid shading from competing

tomato plants and other crops but could be as grown as close as two meters from the female stocks

if necessary. Shaded tomato plants tend to produce fewer flowers and pollen grains than those in

the open, sunny parts of the field.

Field management. The maternal parent, regardless of growth habit, should be staked with bamboopoles after the opening of flowers in the first clusler. This allows for better tending and management

2

of the plants, for facilitating the emasculation and pollination of the flowers, and later, to keep the

ripening fruits from touching the ground and rotting. Determinate parents need only short stakes.

Only indeterminate male parents should be staked for better management. Determinate males

need not be staked.

The female parent is allowed to grow only four branches unless more seeds are needed. Ideally, a

total of 40 to 50 flowers should be pollinated in order to assure good hybrid seed quality from a

limited number of fruits per plant. Number of hybrid fruits to produce per plant depends on , the

average fruit size and seeds per fruit of the maternal parent. The following may be used as a

general rule of thumb: large-fruited parent (20 fruits); medium-fruited parent (30 fruits); small-

fruited parent (more than 30 fruits).

Roguing off-types. Good quality hybrid seeds are not solely judged on physical state of the seeds.

The seed lots must be 100% hybrid or nearly so. For this reason, it is very important that all stocks,

male and female, be pure, i.e. no mixtures and other off-types, before pollination begins. Roguing

of off-types may start at the seedling stage and early plant growth especially if there are easily

visible plant markers that identify the stocks. Before hybridization starts, both stocks are checked

a final time for trueness to type; any off-type or suspected deviants should be eliminated.

General procedures of hybridization

Emasculation. Flower buds about 2 to 3 days away from opening should be chosen for

emasculation. At this stage, the petals slightly jut out of the flower bud and the corolla color is

slightly yellow or even paler (Slides 1 and 2). Emasculating very young flowers could lead toinjury to the style and ovary. On the other hand, of very old flowers are emasculated, the chances

that they have already been self-pollinated are already high. To emasculate, use a sharp-pointed

forcep to force open the unopened bud and the corolla, and then the anther cone (sharp forcepcould easily split this structure). Then, carefully pull the anther cone out of the bud leaving only

the calyx, corolla, ovary, and the style (Slides 3 and 4). Sometimes, the corolla could also be taken

out completely in the same operation. Do not attempt to do this all the time however. It needs

expert hands to attain this. The period of emasculation depends on local climatic conditions and

available resources, and should be determined from experience. In some areas, emasculation is

done in the early morning, during the same day of pollination; whereas in others, flowers are

emasculated up to two days ahead of pollination.

Pollen collection. The male flowers to extract pollen from should be collected in the early morning

hours (Slide 5). Generally, one male flower could pollinate four female flowers. Bring the collected

flowers in the room and take out the anther cones from the rest of the flower. These anther cones

are then placed in a thin cellophane bag (Slide 6) and dried under the light of 100-watt lamp

(about 30 cm above the bag) for 24 hours. Temperature is about 30°C. After drying, all anther

cones are placed in a plastic cup, covered with a fine screen mesh, then sealed with a similar tight-

fitting cup (serving like a lid) and then shook up (Slides 7 and 8). The pollen grains are collected in

the "lid" cup (Slide 9). The cup containing pollen grains are then covered with parafilm, placed in

method uses a specially made vibrator and adopts the same principle of shaking the dehiscentflowers to force the pollen to shed A glass tube or other suitable containers placed at the tip of thevibrator hold the dehiscent flowers at the mouth during vibration. and collect the shedding pollenThe same glass tube could also be used to keep the pollen pool for pollination (Slide 10).

!I

a dehydrator containing silica gel and kept in the refrigerator at 4 2°C. Alternative pollen collection

Polination. The flowers emasculated two days earlier should have completely blossomed andready for pollination (Slide 11). Using a small pair of scissors, cut the corolla and the calyx of theemasculated flower buds to expose the stigma well and to mark the hybrid pollinations. Then, dipthe stigma into pool of pollen kept in a suitable pollen container (Slide 12). Several variants of thetechnique is possible. For example, pollination could be done using fingers dipped at the tip in apool of pollen instead of dipping the stigma into the pollen container. Marking the hybridizedflowers could also vary depending on preferences. In some cases, only two sepals are cut as anindication of hybridization. Pollination is usually done three tunes a week, doing it in alternatedays, but this could vary depending on the rate of flower development under local conditions.Any unhybridized old flowers of the female plant should be removed to lessen the chance ofcontamination from selfed seeds. If they are kept on the plant for some purpose, e.g. maintainingstock seeds, they should be clearly marked (or remain on the plant unmarked to distinguish themfrom marked pollinations). Total pollination period for any seed crop could vary within a 25-35day range. Successful pollinations are easily seen by progressive enlargement of the ovary. Slide13 shows the developing fruits one week after pollination. Note that two pieces of sepals havebeen cut to indicate hybrid pollinations.

Harvesting: The duration from pollination to fruit ripening is about 45 days but could varydepending upon cultivars and season. In warmer climates, plant development tends to be morerapid than under cooler conditions. The pollinated fruits should be kept on the plant until theybecome fully mature (Slide 14), preferably at least pink or red ripe stage (Slide 15). This will enablethe seeds to develop normally and fully and thus have good quality. Fruits at red ripe or earlierstage can be harvested (Slides 16 and 17) and allowed to mature to full ripe stage in a cool, dryplace for 3 to 4 days before processing. Use of nylon net bags in which the fruits can be crusheddirectly for fermentation (see section on seed extraction below) is recommended to minimize extrahandling.

Seed Extraction. Seeds may be extracted in two ways depending upon the amount or scale of seedproduction. With small scale seed production, seeds are traditionally separated from the fruit bykeeping them in nylon bags or other suitable containers and crushing them with bare feet. On theother hand, seeds are extracted with a mechanical extractor in large scale seed production scheme-The following procedures may be followed:

Traditional extraction

1. Harvest the fully mature fruits and keep them in nylon bags or other suitable container (Slide17).

4

2. Crush the fruits by stepping vigorously on the bags (Slide 18). After a while, check if the fruitshave been adequately crushed so that most of the seeds with the gel are virtually out of thefruits.

3. Gather all the net bags into a big plastic container (Slide 19) where the crushed fruits are

allowed to ferment (Slide 20). Time of fermentation depends upon ambient temperature. If

above 25°C, one day of fermentation may be sufficient. If below, fermentation may be allowed

to proceed for two days or so. Do not allow the fruits to ferment for more than 3 days, however.

Mechanical extraction

1. Harvest the fruits at pink stage (Slide 21) and allow them to reach full maturity for about 4 to5 days in a cool, dry place (Slide 22).

2. Put the mature fruits into the mechanical seed extractor for crushing and separation of theseeds and gel from the pulp (Slide 23).

3. Gather the seeds and gel in a suitable, container such as a plastic bucket (Slide 24).4. Treat the seeds and gel with 0.7% hydrochloric acid (e.g., add 7 nil HCI per kilogram of wet

seeds) instead of fermenting then. Stir the seeds and gel while the acid is being added (Slide25).

5. Continue stirring the seeds for about 40 minutes or so, until the gel is visibly softened or

dissolved. Caution: This process should not be allowed to proceed too long because the acidcould impair seed quality.., ;

Seed Washing. To wash the seeds extracted by the traditional method, follow the followingprocedures:

1. Loosen the net bag and pour out the fermented pulp into a pail to less than half capacity, thenfill the pail with water to full capacity (Slides 26 and 27).

2. Stir vigorously to break any caked portion of the fermented pulp. With stirring, the fermented

flesh, skin and gel float up while the heavier seeds sink (Slide 28).3. Incline the pail and gently decant the floating refuse making sure that the seeds remain at the

bottom. Repeat this procedure several times, adding fresh water to the pail every time until

the solution and the seeds at the bottom become clean (Slide 29).

With seeds extracted by the mechanical seed extractor, the following procedures may be observed:

1. Pour out the acid-treated seeds (Slide 30) into a clean net bag and, as the bag is washed with

tap water, step on it to squeeze out the remaining gel (Slide 31).2. Place the seeds into a plastic tank, filling it to a third of the capacity (Slide 32). Then, fill up the

tank with tap water.

3. Stir the seeds to float the small pieces of flesh and skin from the seeds which sink down (Slide33).

4. Incline the pail and gently decant the floating refuse making sure that the seeds remain at the

bottom. Repeat this procedure several times, adding fresh water to the pail every time until

the solution and the seeds at the bottom become clean.

5

Seed Drying

Place the clean wet seeds into net bags (Slide 34) and then dehydrate using an electricdehydrator or a clothes tumble dryer (Slide 35). Dehydration lightly dries up the excessivelywet seeds and loosens up their aggregation. Sun drying may replace above equipment intheir absence. The net bags should be kept hanging to facilitate dehydration.

2. Spread out the lightly dried seeds coming out of the dehydrator into a uniform layer in a flatcontainer, either plastic or aluminum pans (Slide 36). Enclose this container in a suitably sizednet bag (Slide 37). For small seed samples, clumped seeds could be disaggregated by rubbingthem against the sides of the nylon bags (Slide 38).

3. Place the seeds in an air drier kept at a temperature of 28° to 30°C (Slide 39). Stir the seedswith bare hands at least 2-3 times a day, turning them over to dry uniformly (Slide 40).Seeds that stick together should be disaggregated.

4. Seeds should,be dried for 2-3 days, repeating the above process of seed turning. The seedsshould be completely dry to about 6% moisture content. Keep the processed seeds in a cool,dry place where they would be finally packed in suitable containers, either for shipping or forstorage inside cold stores:where their viability could be maintained at high levels until theyare used.

Suggested Reading

Douglas, J. E. 1980. Successful seed programs. VVestview Press, Inc. Boulder, Colorado. USA. 302pp.George, Raymond A. T. 1985. Vegetable Seed Production. The Pitman Press, Bath. England. 318pp.Shinohara, 5. 1989. Vegetable seed production technology of Japan elucidated with respectivevariety development histories, particulars. Vol. 11.317pp. Textbook V. 5. No. 13.

Cultural Practices for Tomato at the AVRDC(Replaces publication AVRDC 79427 Oct. 1979)

Based on AVRDC Conditions

These cultural practices were developed for the specific conditions at the Asian Vegetable

Research and Development Center in Taiwan lowlands. You may need to revise these to fit yourlocal environment. See Guide entitled AVRDC Crop Environment for comparison (AVRDC 78-

66).

Prepared by:

Jen-Tzu Chen, Associate Specialist, Tomato BreedingSylvia K. Green, Plant Virologist

H. Imai, Soil Scientist

George C. Kuo, Plant PhysiologistRomeo T. Opena, Plant Breeder

N.S. Talekar, Entomologist

A. Seed viability aaad eraaaisntioaa

Tomato seeds have no post-harvest dormancy, and usually maintain their viability up to 3-4 monthsat 27°

C and 80% relative humidity. They germinate best in the dark. They require soil moisture at:least 18-25% above permanent wilting point, and soil oxygen content at least 10% for germination.The optimal soil temperature for germination is in the range of 20-30±C. Seedlings usually emergewithin 4-7 day from seed planted at a depth of 0.5-1.0 cm under the optimal condition.

B. Seed treatment

Treat seed with hot water to destroy internal or surface infections before sowing. Partly fill small

cheesecloth bags with seeds and immerse the bags in hot water at 52°C for 30 minutes. Then dipthe seeds in running water, and spread them out to dry. Again treat seed with 75% Thiram orCaptan seed Protestant, according to manufacturer's directions. Hot water treated seeds must besown within 3 days.

C. Seedling production

I. Growing seedling for field planting , allow good control of the environment early, thuspermitting rapid plant growth! It also permits better utilization of land and crop scheduling.Seedlings grown in individual containers, such as clay, paper, peat or plastic pots: plastic bags

with drainage holes: or tin cans produce better stands than seedlings grown in flats or seedling

beds which involved root disturbance prior to field planting. However, former methods areusually expensive and time consuming. Most of common preparation of seedlings is done byseedling flat or bed.

II. For a small area planting use seedling flats as follows:

1 Fill the seedling flat (33x50x7 cm inside dimension) or plastic pots (ID 10 cm) with soil,compost, sand, and rice hulls at the ratio of 3:1:1:1 plus 1.9 g ammonium sulfate, 5.6 g

calcium superphosphate, and 3.4 g potassium chloride. Sterilize the growing medium bysteaming at 100 °

C for 60 minutes, or applying Terrazole (etridiazol 35% WP) at 0.25 g/500ml/flat.

2. Space seedlings in the flat at 5.5 x 6.0 cm, sow 2-3 seeds per pot at a depth of 0.5-1.0 cm, andcover with a thin layer of compost.

3. Cover the flat with a fine mesh screen (Fig. 1) at 30 cm above soil surface in order to keep

temperature low and avoid rain damage during the hot, wet season.4. Thin the seedlings to one seedling only per pot at 2 or 3 day after first true leaf appear.5. Apply a supplemental 2.0 g ammonium sulfate or 1.0 g urea in 400 ml solution or 1.0 g

foliar nitrophoska on 1000 ml water solution to each flat if the seedlings show nitrogendeficiency symptom.

Fig. 1. Cover the flat with a fine mesh screen at 30 cm above seed flat or soil surface.

III. For a large area planting prepare a seedbed as follows:

1. Choose well-drained soil, broadcast and incorporate fertilizers at the rate of 40 g annmonium

sulfate, 50 g calcium superphosphate, 30 g potassium chloride, and 2 kg of compost for

each 1m2 of bed area.

2. Where nematodes are a recurring problem, it may be necessary to fumigate the soil with

nematicides to control them. It is usually necessary to keep the soil moist for at least 24

hours before fumigation. Ask pathologist what fumigant to use and how to treat the soil.

Always follow manufacturer's directions carefully concerning dosage and methods for

use. Operators should use respirators and wear protective clothing.

3. Prepare bed 15 cm high and 0.8 m wide, and plant the seed in rows 6 cm apart at a depth of

0.5-1.0 cm. Cover the bed surface with a thin layer of compost or ash before mulching with

rice straw or rice hull and covering with mesh screen at 30 cm high.

4. Care must be taken to prevent the soil from drying out and forming a crust on the soil

surface. This crust often prevents seedling emergence, resulting in poor stand.

5. Seedlings must be thinned within 2 or 3 days after the first true leaf appear.

IV. During the hot, wet season in the tropics, the seedlings may not be planted as scheduled due

to excessive rain-fall in the field. The seedlings usually result in spindly and weak growth in

the seedling bed or flat due to high humidity, high temperature, and low light intensity in

protective structures while waiting for field planting. Either one of the following measures

may check the spindly and weak growth, and enhance the survival of plants after field planting.

1. Gradually decrease the frequency and amount of irrigation, resulting in a natural hardening

off the seedlings.

2. Lift the seedling slightly with a pitch fork or by cutting the roots on both sides of the rows

of plants. In both cases, the water absorbing surface of the root system is reduced and, if

the treatment is severe enough, growth is checked and hardening results.

3. Transplant the seedlings into pot, blocks, flats or beds in wide spacing, and transplantthem in the field as soon as the field is manageable.

4. Spray CCC (Cycocel, x-chloroethyl trimethyl ammonium chloride, chlormequat chloride)

at 200 ppm in the aqueous solution to the seedlings, and plant the seedlings to the field assoon as the field is manageable.

D. Landpreparation

Tomatoes can be grown on soil texture ranging from sand to heavy clay, but sandy or sandy loam

soils are preferable. Soil pH should range from 6.0 to 7.0. Choose land after paddy rice in order to

reduce nematode incidence. A well-drained soil is essential for high production. If the land is dry,

irrigate 3-4 days before land preparation. Plow the land with a rotator, but tillage with a water

buffalo is superior to a rotator during- the rainy season. To trap solar radiation efficiently, arrange

planted rows in north-south direction. Mulch the bed with rice straw after planting during the hot

rainy season in order to reduce soil erosion and temperature, and to suppress weed growth.

E. Field planting

1. About 6-9 days before field planting, harden the seedlings by slightly withholding water andexposing them directly to sunlight by removing the net cover. Thoroughly water plants 12 to

14 hour before planting to the field.

2. The ideal seedling has 4 to 5 true leaves, or about 12 to 15 cm in the length devoid of developed

flowers, disease-free and vigorous. The seedlings usually need 3-4 weeks of growth prior to

field planting.

3. Dig a hole and insert the plant so that the cotyledon appears above the soil surface. Leggyplants, which have grown past the ideal size for field planting, should be buried deeper.

Removing a few older leaves in leggy plants can make planting easier.

4. Press the soil firmly around the root. Then top irrigate lightly to settle the soil. Furrow irrigate

the field as soon as possible.

5. Field planting should be done in late afternoon to minimize transplanting shock at high

temperatures.

6. About 7 days after field planting, replace missing plants.

F. Fertilization

The nutrient uptake by a tomato plant at a given yield is usually the same no matter where it is

grown. However, fertilizer requirements vary from field to field because of differences in soil

supplies of nutrients and efficiency of nutrient uptake. Application rates from any given nutrient

can be expressed as: Nutrient Requirement = (Total Nutrient Uptake - Amount Available in soil)/

Efficiency of Uptake.

I. Amount of nutrients in the soilThe existing supply of nutrient in the soil obviously determines the amount of additional

supplied needed. The higher the soil supply, the less need be applied. The levels of plant

nutrients in the soil is a reflection of soil parent material, past fertilizer practices, and croppinghistory. Also, the nutrients must be available to the plant.Soil analysis and interpretation of result usually should be done by experienced persons.However, the following simplified chemical tests may be employed if a chemical-testinglaboratory is not accessible. A range of standard solution of each nutrient should be preparedand processed according to the procedure described.

1. Nitrate nitrogen test: Prepare an extract by vigorously shaking 2 g of fine soil sample in 5ml of extracting reagent for exactly 3 minutes. Filter immediately. The extracting reagentis 2 N copper sulfate with 0.05 g of calcium hydroxide and magnesium carbonate mixture(2:5 ratio). One ml portion of filtrate is added with 0.05 g each of two reaction reagents.The first reaction reagent is consisted of N-1-naphthylethylene diamine dihydrochloride(0.5 g), sulfanilic acid (10 g) and citric acid (100 g), and the second reaction reagent isconsisted of manganese sulfate (5g), zinc powder (1 g) and potassium sulfate (94 g).Shake both solutions vigorously for twenty seconds and let it stand still for 5 to 10 minutes.Compare the resulting color reaction.

2. Ammonium nitrogen,test: Prepare an extract by vigorously shaking 2 g of fine soil samplein presence of 5 ml of 10% of sodium acetate at pH 5.2 for 3 minutes. Filter immediately.Add 0.3 ml of Nessler's reagent and shake. Nessler's reagent is made of 45.5 g of mercuriciodide 34.9,g of potassium iodide, and 112 g of potassium hydroxide in 1 liter of water.After stand still for 3 minutes. Compare the resulting color reaction.

3. Available phosphate test: Shake briskly 5 g of fine soil in 10 ml solution of acetic acid (0.5N) and sodium acetate in pH 4.8. Filter immediately. One ml of this filtrate is used for thedetermination of phosphoric acid by adding 1 ml of reaction reagent. The reaction reagentis a 2.5% ammonium molybdate solution in 10 N sulfuric acid. After 10 minutes comparethe resulting color reaction.

4. Available potassium test: Take 1 ml portions of the filtrate from the ammonium nitrogenextraction, and add 0.15 ml of formalin in the filtrate and shake well for 3 minutes beforeadding 0.5 ml of 20% trisodium cobaltinitrite solution and 1 ml of pure ethyl alcohol.After 3 minutes shake and compare the turbidity.

5. The nutrient concentration figures (mg nutrient/100 g soil) at 12 cm depth of soil analysiscan be converted to kg/ha by multiplying it with one of the constant in the Table 1depending upon the soil type.

Table 1. Multiplication constants of variou soil types.

Soil type (Bulk density) Constant

Volcanic ash soil (0.6) 7

Clayey plowing layer (1.0) 12Alluvial oil (1.5) 18Sandy or compact soil (1.9) 23

4

For example, 10 mg N/100 g soil from the alluvial soil (Bulk density = 1.5) is equivalent to10 x18 = 180 kg I\1/ha.

The desired nutrient level in 100 g of dry soil are inorganic N at 10-15 mg, available

phosphate (P2O5) at 1.0 mg, and available potassium (K2O) at 20-40 mg. If values from asoil test are found below these figures, fertilizer application usually is necessary.

II. Efficiency of nutrient uptake

The efficiency of nutrient uptake is highly influenced by both chemical and physical soil

properties. The efficiency of uptake can range from 40 to 80% for nitrogen; from 10 to 40% for

phosphorus; and 35 to 80% for potassium. General values estimated at the AVRDC conditions

are 60% for nitrogen, 40% for phosphorus and 80% for potassium.

III. Total nutrient uptake

Using the plant and fruit average as an indicator it is estimated that approximately 110 kg N,32 kg P2O5 and 150 kg K2O are taken up by', \the plant to produce 40 t of tomatoes per ha. The

nutritional problems can be expected only with yields of above 15 of tomatoes per ha. In many

cases factors other than nutrition are currently limiting tomato yields in the tropics.

IV. A soil analysis may be used a starting point for evaluating the fertilizer needs but that no

method of soil analysis is absolutely perfect and that exceptions will undoubtedly occur. The

field trial as a specific location is considered to have the last word in establishing fertilizer

requirements.

1. The following general fertilizer recommendations were developed for the AVRDC andshould be used as a guide in your specific conditions. Adjustment may be necessary

according to information from a soil test.

Time of Compost Nutrients (kg/ha)

Crop type application (kg/ha) N P205 K 2 O Borax

Fresh market 1st: Basal 20.000 40 80 60 5(Indeterminate) 2nd: 10 days after planting 0 20 0 30 0

3rd: 3 weeks after planting 0 60 20 60 04th: 6 weeks after planting 0 60 20 30 0

Total 20,000 180 120 180

Processing and 1st: Basal 20,000 40 80 50 5Fresh market 2nd: 1 week after planting 0 20 0 50 0

(determinate) 3rd: 4 weeks after planting 0 60 20 50 0

Total 20,000 120 100 150 5

2. For efficiency of field operations, mix appropriate amounts of as many forms of chemical

fertilizers as possible whenever circumstances permit. However, thoroughly mix the

combined fertilizer prior to their use to ensure uniformity of application.

3. Side dressed chemical fertilizer should be covered with soil to minimize escape of nutrients.

4. For the heavy texture soil, 20 t/ha of compost can be applied. If compost is applied, the

amount of fertilizer should be reduced according to the amount and composition of

compost used. Generally, compost consists of 0.5% N, 0.24% 1'205, and 0.5% K2O.

V. Tissue analysis of the plants is an indication of soil nutrient level. Although nothing as a rule

can be done about the current crop, needed adjustment can then be made for the future crop.

The indicator tissue taken for the tissue test is the fifth leaf down from the growing tip of the

main stem and includes both the leaf petiole and the several leaflet. Tissue analyses are usually

done in a chemical testing laboratory..

1. Nitrate nitrogen is an indicator of the nitrogen status of the plant. Leave of deficient plants

usually contain 0.1% nitrate nitrogen (expressed on dry matter) or less, in healthy plant

this level is normally 0.5-1.5%.

2. Leaves of phosphorus deficient plant usually contain less than 0.4% P2O5 (expressed on

dry matter); in healthy plant the level is normally 1-1.5% P2O5.

3. Leaves of potassium-starved plants normally contain less than 1% K2O (expressed on dry

matter). In healthy plants leaf potassium may vary from 3 to 8% K2O. The optimum level

depending on calcium concentration. The potassium content required for optimum quality

is higher than for maximum production.

VI. An abnormal appearance of the growing plant may be caused by a deficiency of one or more

nutrient elements. If a plant is lacking in a particular nutrient, more or less characteristic

symptoms may appear. This visual method of evaluating soil fertility requires no expensive

or elaborate equipment and can be used as a supplement to other diagnostic techniques.

1. Nitrogen deficiency: Leaves show a generalized chlorosis (yellowing). Overall growth is

impaired and older leaves drop off. The stems are yellow and rigid.

2. Phosphorus deficiency: The leaves, especially at the midrib, veins and petioles, darken

and show a dull purple tint.

3. Potassium deficiency: Leaf margins die and leaves are mottled. Leave curl down, showing

a slightly convex upper leaf surface.

4. Boron deficiency: Light, medium and dark splotches of purple, brown and yellow appear

on the leaves. Growing points die back. The stems become stiff and straight.

If any of the symptoms is observed early, it can be corrected during the current growing

season by side-dressing or foliar applications. However, if the trouble is properly diagnosed

at the later stage, the deficiency of the following crop can be fully corrected.

G. Crop management

I. Terminal buds of determinate tomatoes (Fig. 2) set fruit and stop stem growth. The plant is

self-topping and seldom needs staking. All blossoms and fruit develop on a plant at the

short period of time. Harvest time is usually short, and ideal for processing.

1. Broadcast basal fertilizer before plowing. Refer to section F. Fertilization for rates and

schedules.

2. Form the bed 100 cm wide with a plow by opening equidistant furrow at 50 cm to a

depth of 20 cm during the dry season or 30 cm during the west season.

6

7th leaf

detopping

Fig. 2. Determinate type

3. Plant seedlings in the middle of bed with 30 cm spacing between plants during the wetseasons or 40 cm during the dry season (Fig. 3).

4. After the second side dressing, bank the bed to a width of 100 cm by plowing in themiddle of furrows.

Fig. 3. The different bed types of tomato production

II. Terminal bud of indeterminate tomatoes (Fig. 4) does not set fruit, it always produce leavesand branches. The vine can grow indefinitely if the environmental condition permits. Theblossoms and fruit develop progressively as the vine grows so tomatoes in all stage ofdevelopment may be on the vine at one time and the harvest may last long. It is usuallyideal for fresh marketing.

7

Fig. 4. Indeterminate type

1. Form the bed 100 cm wide with a plow by opening equidistant furrows at 50 cm to a

depth of 20 cm during the dry season or 30 cm during the wet season.

2 Dig one row to a depth of 15-25 cm in the middle of bed, place basal fertilizer into the

row and cover with soil prior to field planting and spraying with herbicide.

3. Plant seedling on top of the row of fertilizer and space seedlings 40 cm between plants.

4. Stake (Fig. 5) each plant with a 150-180 cm pole 3-4 weeks after field planting.

Fig. 5. The staking type of fresh market tomato.

5. Tie the vine to the stake and pinch off the sprouted axially bud in order to maintain a

single stem per plant.

6. It is a common practice to decapitate all sprouting axially buds above the 2nd or 3rd

leaf formed after the 5th cluster. However, if the environment is most favorable, it is

possible to maintain 7 to 8 clusters. Fruit pinching to maintain 4 to 5 fruits per cluster

allows uniform and large size fruit to develop.

H. Weed control

I. Near time of field planting:

To control n.utsedge, repeated post-emergence treatments of Roundup (glyphosate) at 1.5

kg a.i/ha. Stop application at 7 days before/and preparation.

II. At time of field planting:

1. Spray Sencor (metribuzin) with a hand sprayer at the rate of 0.25 kg a.i.'/ha on the top

of bed before field planting. Sencor is more effective when the soil is relatively moist.Spray within one week after field planting, except summer season.

2. Rice straw or silver-black plastic sheet mulch on the top of bed will suppress weed

growth. However, some grasses can penetrate the mulch cover. These weeds can bemanaged by hand weeding.

3. ` Weeds in furrows may become unmanageable especially during the rainy season. In

this case, spray Gramoxone (paraquat) at 0.5 kg a.i./ha in furrows using a sprayer with

a shielded nozzle to prevent contact\with tomato plants.

I. Irrigation practices

1. Tomato plants require moist soil for good growth throughout their growth period. Sporadic

or uneven water supply during the reproductive phase is the most frequent cause ofphysiological disorder of fruit.

2. Symptoms of wilting in the morning continuously for 2-3 day, indicates there is shortage

of water in the soil. Temporary wilting may occur at midday under hot conditions even

though soil moisture is adequate. On the other hand, poor drainage at hot season may also

cause wilting.

3. The appearance or feel of the soil at the root zone will also indicate moisture content. At

optimum moisture, soil adhere and form a ball when squeezed in the palm of hand andwill not break away when poke lightly with a finger.

4. A general rule is that tomatoes need an average of about 25 mm per week of precipitation,

whether as rain or supplemental irrigation. In dry, hot regions, 30 mm or more per week

are required.

5. The times of auxilliary irrigation during tomato growing periods will be recommended as

follows:

Table 3. The schedule of auxiliary irrigation during tomato growing periods.

Irrigation time Remarks

Furrow irrigation at tillage about 7 days before transplanting.

Furrow irrigation and watering immediately at transplanting.

Furrow irrigation 20-25 days after planting. ()begin flowering)

Furrow irrigation 45 days after planting. (fruit setting stage)

Furrow irrigation after 1st harvesting

1st

2nd

3rd

4th

5th

9

K. Chemical fruit ri etpLgi1

Ethrel (ethephon) can be used for uniform ripening for once--over harvest or to enhance ripening

in late varieties of processing tomatoes. Spray 4 to 71 of Ethrel/ha in 600 to 1000 I/ha of waterwhen 15 to 30% of the fruit is ripe. The key to good result is good coverage. Use lower rates

when day temperatures are higher than 30°C. Harvest fruits at 14 to 21 days after treatment.

Fruits are not appreciably increased size after Ethrel treatment.

L. Harvesting and handling

Tomatoes fro processing must be harvested when the fruit is fully ripe. However, they are not

suitable for long distance shipment. Tomatoes grown for distant fresh market should be harvestedat e color turning stage (Table 4). At this stage, fruits should slightly show pink, especially on the

blossom end, with most of the fruit surface till green. To pick fresh market tomatoes, bend the

fruit appropriately by peduncle joints with finger nails. Cutting by scissors may spread virusa

disease.. Harvest fruit early in the morning to avoid- the risk of heating and post-harvest rot.

Table 4. Ripeness classes of tomatoes

Score Class Description

1 Green mature Entirely light to dark green, but mature

2 Breaker First appearance of external pink, red or tannish-

yellow color; not more than 10%

3 Turning Over 10% but not more than 30% red, pink or tannish-

yellow4 Pink Over 30% but not more than 60% pinkish or red

5 Light-red Over 60% but not more than 90% red

6 Red Over 90% red; desirable table ripeness

M. Seed production

1. Inbred varieties

Fruits of inbred (PO) varieties can be harvested for seeds, since most of them are selfpollinated.

a. Select and harvest fully ripe fruits which possess a large number of seeds, crush well in a

non-metal container to make a paste, and then ferment the paste for 1 to 2 days according to

temperature.

b. When fully fermented, stir the pate vigorously. Foam and flesh will float on the top, while

the seeds will settle down to the bottom of container. Remove the fermented mass and

gently decant the liquid.

c. Collect the seed and wash them several times with tap water, and spread them to dry under

the sun or in the 32°C oven for 3 days. Store seeds in airtight containers in a cool dry place.

2. Fl hybrid varieties.

See attached article "Production of F 1 Hybrid Seeds in Tomato"

10

J. Crop protection

Plant disease becomes the limiting factor in tomato production in many parts of the world when

cultivars with resistance to numerous diseases are not planted. Good management over all aspects

of crop growth results in good disease control and increased profit. A good grower watches his/her crops closely and is quick to spot the first sign of disease.

The pesticides are not miracle chemicals - if disease is advanced before spraying is undertaken

they cannot return the crop to its previous healthy and unblemished condition, at best they can

stop the disease progressing. On the other hand, blanket spraying to prevent disease before anysymptoms appear is irresponsible and costly - the disease program may not be present on the

weather may not be suitable for disease. The type of control measure to be used will depend on

the type of disease present, and generally speaking disease control measures should be consideredlong before the crop is planted.

The causal agents of tomato disease can be classified to 1. parasitic diseases which caused by

bacteria, fungi, viruses, viroids, nematodes and insects. 2. Nonparasitic disorders which caused

by physiolical problem. The followings are considered to be major in the tropics and subtropics.

(A) Parasitic diseases

I. Bacterial diseases

1. Bacterial wilt ( pscudornoi as solanaceartim )

Symptoms:

The first appears as flaccidity in one or more of the youngest leaves. Under favorable environmental

conditions, a rapid and complete wilt soon follows. Advanced stages of the disease may occur 2-3 days after the appearance of initial symptoms. The vas–.ular system in the stem of a plant in theearly stages of the disease appears yellow or light brown in transverse or longitudinal section. It

becomes a darker brown as the disease progresses. When the plants is completely wilted, the pith

and cortex also become br3wn. Massive invasion of the cortex may result in the appearance of

water-soaked lesions on the external surfaced of the stem. If an infected stem is cut crosswise, tiny

drops of dirty wllite or yellowish viscous ooze exude from the severed vascular bundles. Bacterial

wilt can easily be distinguished from the vascular diseases caused by fungal pathogens bysuspending a clean section of diseased stem in water. A white, milky stream of bacterial cells and

slime flow from xylem elements of the infected plant in 3-5 min. If the stem is severely infe–ted.the water become completely milky in 10-15 min.

Conditions:

The bacterium survives in soil and can infect naturally through root or be introduced by pruning

or cultivation wounds. The disease develops best during warm we–then (optimum 28-32°C) and

at high soil moisture levels.

Control:

The only practical means of control is the use of resistant varieties. However. the extent of this

disease can be minimized by the following measures.

1 1

1. Crop rotation with a nonsusceptibl.e crops especial paddy rice.

2. Select land with good drainage.3. Soil treatment with a general purpose fumigant before planting.4. Remove infected plants from the field and burn them immediately.

5. Tomatoes are grafted on resistant solanaceous rootstocks.

6. Use resistant varieties.

2. Bacterial spot ( Xantlromonas campestris pv. vesicataria )

Symptoms:

The bacterium affects all aboveground plant parts. On the leaves, stem, clusters and fruits, thespots are generally brown and circular. The spots are water-soaked during rainy periods or whendew is present. Lesions rarely develop to more than 3 mm in diameter. Bacterial spot lesions donot have concentric zones, as do target spot and early blight lesions, and they are generally darkerin color, and less uniformly distributed tha-gray leaf spot lesions. When conditions are optimalfor disease development, spots on the leaves, petioles, and rachis coalesce to form long dark streaks.A general yellowing may occurs on leaflets with lesions. Fruit lesions begin as minute, slightraised blisters. As a spot increases in size it becomes brown, scablike, and slightly raised. However,lesions may also be raised around the margins and sunken in the middle.

Conditions:

The organism is able to survive on tomato volunteers and diseased plant debris. Seed may alsoserve as a medium for the survival and dissemination of the bacterium. Disease development isfavored by temperatures of 24-30°C and by precipitation. The bacterium is disseminated withinfields by wind-driven rain droplets, the clipping of transplants, and aerosols. It penetrates throughstomatas and wounds created by wind-driven sand, insect punctures, or mechanical means. Warmtemperatures coupled with sprinkler irrigation or heavy rains are favorable for disease

development.

Control:

1. Rotate fields in an attempt to avoid carry over on volunteer and crop residue.2. Produce disease-free transplants. This is facilitated by raising the transplants in an area where

tomato and pepper production does not occur.

3. Use seed treatment to reduce possible transmission of the bacterium.4. Eliminate any potential for volunteers.5. Avoid cull piles near greenhouse or field operations.6. Apply bactericides or fungicide - bactericide combinations where recommended (such as

Kocide 101 is one kind of copper hydroxide)

3. Bacterial canker [Clavibacter michiganensis subsp. michiganensis (smith) ]

Symptoms:

The principle symptom of canker is a systemic wilt of plant. The first symptom is wilting of lowerleaves of plant. Leaflets often wilt only on one side of the leaf. Leaf petioles characteristicallyremain attached to the stem. Internally, stems show light brown or yellow vascular discolorationand often the pith is yellow and hollow. Wilting may be accompanied by light streaks which

1 2

extend down the stem from the petiole. Later—these streaks can break open to form cankers

characteristically. A yellow slime can be squeezed from infected stems. Fruit infection occurs as

small, white spots, which develop into brown, scabby lesions. These lesions are surrounded by

white haloes giving the fruit a birds-eye appearance. Symptoms in the root are not diagnostic.

Conditions:

Initial infection can occur through stomata, but generally some woanding of the leaf epidermis,

leaf hair or root is required. Infected plant debris in soil can be the source of infection. The organismcan also be carried on or inside tomato seed. The bacterium spreads primarily through root injury

transplanting wounds, especially from contaminated knives. The disease progresses quickly in

succulent, fast growing plants.

Control:

1. Using seed produced from disease free areas.

2. Sterilization of transplanting mix., flats adbenches.

3. Sterilize the seed bed before sowing.

4. A crop rotation to a non-tomato relative of at least three years.

II. Fungal diseases

1. Damping off (Phizoctonia solcwi, phytophthora capsici, or Phthium aphanidermature)

Symptoms:

Pre-emergence damping-off occurs when the seed or seedling decay before it emerges. Post-

emergence damping-off occurs above ground, and young seedlings eventually wilt and falling

over. The stem usually becomes soft, water soaked, dark and shriveled at the soil line before the

plant collapse. Roots may also be affected resulting in seedling death.

Conditions for disease development:

The disease may occur under warm and high soil moisture condition. Seedlings during the first to

second weeks after emergency are particularly susceptible. Usually, it occurs in overwatering,

overcrowding, poor ventilation and cloudy in the seedbeds.

Control:

Using high quality seed with good vigor, seedling medium sterilization before sowing. Othercontrol methods as follows:

a. Soil sterilization of seed beds or the use of sterile growing media.

b. less-watering in the seed bed

c. Drenching with effective fungicides after planting.

Southern blight (Sclerotium rolfsii)

Symptoms:

The first symptoms are a general wilting of the plant. Wilting progress without a change in foliage

color until the plant finally die. The base of the plant is girdled with a white growth covering the

dead tissue. Embedded in this white mat are light brown bodies about the size of mustard seed,

1 3

which are characteristic of this disease. Fruits also infected when they are touching the soil.

Conditions:

The disease occurs under high temperature and high moisture levels. The fungus can survive in

soil for several years and can be spread in running water, in infested soil, in infested plants, on

tools and implements, and as scherotia among the seed.

Control:

The most effective control is a good sanitation program, other control measures are as follows:

a. Removal and burning of all infected plants

b. Crop rotation at least three years with crops such as corn or sorghum

c. Cultural practices, such as careful regulation of soil moisture and deep ploughing of residue

d. Soil fungicide application

3. Late blight (Phytophthora infestans)

Symptoms:

The first symptoms of the disease are a bending down of the leaf petiole. Lesions produced on the

leaves and stems are large, irregular, greenish, water soaked patches. As these patches enlarge,

they turn brown and paper-like. During wet weather, the lesions on the leaf under surface have a

fine, white mold ring around them. Blighting of the entire foliage may occur during moist, warm

periods. Entries fields can have extensive foliar and fruit damage. Fruit lesions are firm, large,

irregular, brownish-green blotches. The surface of the fruit lesion has a greasy, rough appearance.

Conditions:

The fungus survives on weeds of solaneous crops. Spores of the fungus can be carried long distances

by storms. Cool (15-20°C), wet weather is required for late blight to develop. Under these condition

the disease progresses rapidly and can ruin a mature tomato field in a few day.

Control:

1. Avoid land previously to crop Solaneous crops.

2. Fungicide spraying schedule are the most effective method of control.

4. Early blight (Alternaria solani)

Symptoms:

It occurs on foliage, stem, and fruit of plants. The symptom appear first as small brownish, black

lesion on the older leaves. The lesions area are about 6 to 16 mm diameter. These leaf spots typically

have concentric, black rings giving an oyster shell, or target-board appearance to the lesions. A

yellow area surrounds the spots and it there are many lesions the whole leaf turns yellow and

quickly dries up. Lesions may occur as brown elongated, sunken areas anywhere on the stem or

petioles. The fruit becomes infected, generally through the calyx or stem attaclunent, in either the

green or ripe stage. The lesions appear leathery, sunken with concentric ringing.

Conditions:

The fungus can be survived between crops on infected debris in the soil and on seed. It also survives

1 4

from season to season on volunteer tomato plants and other solanaceous hosts. First infectionoccurs during periods of warm (24-30°C), rainy or humid weather. The fungus is rapidly by windand rain,

Control:

1.. A regular spray program is the most effective method.

2. Benlate (benomyl 0.14 kg a.i./ha) with Manzate D (0.6 kg a.i./ha) are recommended.

3. Burn affected plants after harvest.

5. Black leaf mold (Pseudocercospora fuligena)

Symptoms:

Small lesions develop on young leaflets as indistinct discolorations with no definite margins. As

the size of a lesion increases, a faint halo appears at the lesion margin and surrounds a brownish

margin of collapsed tissue on both the upper and lower sides of the leaflet. Under humid conditions,heavy conidial production may be observed,on lower leaf surfaces.

Conditions:

The spores are disseminated by splashing rain, running water, or machinery. Infection occurs

rapidly, but symptoms develop slowly over 2 weeks. Sporulation occurs on the lower

leaf surfaces under high humidity. Disease development is favored by warm (27°C) and wet

weather.

Control:

1. All crop residue should be destroyed and plowed under following the last harvest.2. Staking and pruning increase air ci r culation and reduce disease severity.

3. Apply efficacious fungicides.

4. Use tolerant and resistant cultivars.

6. Leaf mold (Cladosporium f-ulvum)Symptoms:

First symptoms appear on the upperside of older leaves as yellowish or pale green spots.

Purplish, or olive green mold appears on the lower side which coincides with a yellowing on

the upper leaf surface. Later the infected lower leaves of the plant turn yellow and drop off.

Conditions:

The disease develops quickly on high relative humidity (90%) and temperature (between 22°C

and 24°C). The conidia, which are readily disseminated by rain or wind, can survive at least one

year.

Control:

1. Crop residue should be removed and destroyed once the tomato crop is harvested.2. The greenhouse production areas should be steamed (55°C) for a t least 6 hours once the

crop residue is removed out.

3. Staking and pruning to increase ventilation helps to control the disease

15

4. Spray with fungicides on a regular schedule 5. Grow resistant cultivars.

7. Powdery mildew (Leveillua taurica)

Symptoms:

The most common symptom are light green and bright yellow lesions on the upper leaf surface.

Necrotic spots, sometimes with concentric rings similar to those of earl blight lesion, may develop

in their centers. A light powdery covering of these lesions may occur on the lower leaf surface.

Heavily infected leaves die but seldom drop from the plant.

Conditions:

The spores of the fungus can travel long distances in air currents and are able to germinate under

low relative humilities. The disease develops quickly in warm (near 25°C) and relative humidity

of 70 to 100%.

Control:

1. Apply sulfur fungicides early and regularly.

2. The best control is application'of mildew fungicides at the first sign of the disease.

8. Fusarium wilt (Fusariunt oxysporum Schlechtend: Frfsp.)

Symptoms:

The earliest symptom is the yellowing of the older leaves. This often develops on only one side ofa leaf or branch. The affected leaves wilt and die thought the remain attached to the stem. The

whole plant appears stunted. A characteristic red-brown to brick red discoloration of the outer

portion of the vascular tissue is evident, which extends far up the plants. But the pith remains

healthy.

Conditions:

It is a warm-weather (soil and air temperatures of 28°C) disease, most prevalent on acid sandy

soils with low N and P and high K, short day length, and low light intensity. The pathogen is

soilborne and remains in infested soils for several years. This disease can be dissemination by

seed, tomato stakes, soil, infected plants, farm machinery, windborne, and waterborne infested

soil. 20

Control:

1. Use resistant cultivars

2. Don't flood the land

3. Keep tomato field away from seedling production houses or seedbeds.

9. Verticillium wilt (Verticillium dahliae)

Symptoms:

Often the first indication of Verticillium wilt is a diurnal wilting pattern. Plants show mild to

moderate wilting during warmest part of the day but recover at night. As the disease advances,

some marginal and interveinal chlorosis develops on lower leaflets. These lesions show

1 6

characteristic N-shaped. When the base of the main stem is cut a light tan discoloration with

scattered, darker brown spots can be seen, which extends across the vascular system. The

discoloration usually does not extend far up the plant, so there is no vascular browning in petiolesor pith.

Conditions:

This disease is a cool-weather disease the day time high temperature averaged 20-24°C. It seems

to be more severe in neutral to alkaline soils. The infection is usually through wounds on roots.

Control:

1. Use resistant cultivars

2. Fumigation using methyl bromide-chloropicrin

3. Solar sterilization in hot, acid areas is also effective

10. Phytophthora blight (Phytophora capsici and P-Pasasitica)

Symptoms:

Above or below the soil line brown lesion develop which may eventually girdle the stem or

root. These brownlesions become large and sunken. A chocolate-brown internal discoloration

of the vascular system extends above and below these sunken, brown lesions a short distance.

Eventually the stem or roots may rot and plant wilts and dies.

Conditions:

The fungus is favored by high soil moisture and hot weather (30-35°C). Usually, over irrigation or

excessive rain, can be caused severely infection.

Control:

Cultural methods which encourage water percolation help control this disease. Some of these

methods are:

1.Avoiding soil compaction

2. Preparing high beds which allow better drainage

3. Using shorter irrigation to avoid extended periods of soil saturation

11. Anthracnose (Colletotriclzum coccodes)Symptoms:

The fruit may be infected when green and small but symptom do not appear until it begins to

ripen. The first noticeable symptoms of the disease on the ripen fruit as small, slightly depressed,

circular lesions. A lesion may enlarge to 12 mm in diameter and becoming more sunken, with

concentric ring markings. The flesh beneath a lesion may be of a lighter color than the surroundingtissue and granular in texture. The center of a lesion is usually tan, and as the lesion matures it

becomes dotted with small black specks. The surface of a mature lesion generally remains smooth

and intact. During moist weather, masses of salmoncolored sprees may be present on the lesion

surface. Infection may also occur on stem, leaves, and roots. Leaf infection are characterized by

small, circular, brown lesions surrounded by yellow hales. Infected root exhibit brown lesions,

1 7

Conditions:

The fungus can penetrate the fruit skin directly or enter the fruit through a wound such as forminsects or growth cracks in the fruit. Although the fungus can infect green fruit, but symptoms are

produced only after the fruit ripen. The fungus survives on decayed plant material in the soil.Splashing rain carries the fungus from the soil to the fruit.

Control:

1. Rotation with nonsolanaceous crops at least every other year.

2. Weed control to reduce hosts.

3. Apply fungicides periodically from first fruit set to harvest, especially important as the fruit

begin to ripen.

4. Staking plants and mulching (with straw or plastic sheet, etc.) can be to reduce infection.

12. The following fungicides were used based on recommendations by AVRDC

pathologists.

Fungicides Dosage (kg a.i./ha) Dilution

a) Dithane 45 (WP) 2 1:400

b) 50% Benlate (WP) 0.3 1:2000

c) 75% Daconil (WP) 1.5-2.0 1:600

d) 77% Kocide 101 (WP) 1.5-20 1:600

e) 58% Ridomil- M2 (WP)

(Mancozeb + Me2talaxyl)

2.5-3.8 1:400

f) 35%Terrazole (WP)

(Etridiazole)

0.45 1:2000

111. Virus

1. Tomato mosaic (Tomato mosaic virus)

Symptoms:

The symptoms are mottled areas of light and dark green on the leaves which caused by

common strains. Some other strains may cause a striking yellow mottling. Planted infected in a

early stage of growth are usually stunted and have a yellowish cast leaves may also be curled,

reduce in size, and malformed (fernleaf). Sometimes, the necrosis of leaves, stems or fruit result

from infection by some strains of TMV, while chlorosis of leaves results from other.

18

Conditions:

The virus is ecsily transmitted mechanically by machinery or workers from infected in healthyplants any time during the handling of the tomato plants. TMV may be present in cigarette and

other tobG-,cos, which can lead to workers transmitting the disease. Infected debris from a previous

crcp can lead to infection through the roots of the new tomato plants. Chewing insects, such as

grasshoppers and beetles, can transmit the virus, but are not considered a major source of infection.

Control:

1. Seed treatment with a 10% solution of trisodium phosphate for 20 min, or heat treatment ofdry seed two days at 78°C.

2. Washing hands with sink milk or soap, before and during the handling of plants.3. Avoid planting in soil which contains the virus from. previous crops of tabacco, tomato, pepper

or eggplant.

4. The soil media of seedbed should be steam sterilized for 60 min at 100°C where ust follow

susceptible crops.

5. Sink milk sprays on the foliage can reduce mechanical transmission.

6. All pruning tools should be dipped in mild or 10% trisodium phosphate soluation.7. Use resistant cultivars.2. Cucumber mosaic (Cucumber mosaic virus)

Symptoms:

The systems in early stages are yellow, bushy and stunted. The leaves may show a mottle similar

to TMV. The most characteristic symptom of cucumber mosaic is shoestring-like leaf blades. In

fernleaf, the blade of the leaflet is not as completely suppressed as in a shoestring leaflet, but it is

abnormally long and narrow. Severely affected plants produce small, few fruit and irregular shape.

Conditions:

Aphids usually introduce CMV into a tomato crop from weeds or crop plants in adjacent fields.

Secondary infection by aphids may occur, or less often. Workers may spread the virus from infected

to healthy plants. 24

Control:

1. Control aphids in seedbeds or field planted beds by insecticides.

2. Raising seedlings under insect proof net cover.

3. Elimination of weeds and ornamental plants.

4. Remove the infected plants and burn them as soon as possible.

3. Tomato yellow leaf curl (Tomato yellow leaf curl virus)

Symptoms:

The plants infected at an early age are severely stunted and bushy; their terminal and axially

shoots are erect, and their leaflets are reduced in size and abnormally shaped. Foliages are vein

clearings, reduced leaflet size, downward curving and upward curling of leaflets, interveinal

chlorosis; a rosette like growth habit and a profusion of axillary branch formation. Later leaf

veins become thickened and puckered with enations. Usually flowers are sterile.

1 9

Conditions:

The major infections of the tomato crop coincide with crop establishment and occurrence of

large populations of sweet potato whiteflies.

Control:

1. Applications of insecticides with mineral oil sprays. (1-lipar or Sunaco) may reduce the

incidence of this disease

2. Schedule the planting date of tomatoes to avoid periods when the sweet potato whiteflypopulation is highest.

4. Tomato spotted wilt (Tomato spotted wilt virus)

Symptoms:

Symptoms of spotted wilt vary, but young leaves usually turn bronze and later develop

numerous small, dark spots. Growing tips may die back, and stem of terminals may be

streaked. Affected plants may have a one-sided growth habit or may be entirely stunted and

have dropping leaves, suggesting a wilt. Plants infected early in the season may produce no

fruit, and those infected after fruit-set produce fruit with chlorotic ring spots. Green fruit has

slightly raised. areas with faint concentric rings; on ripen fruit these turn into obvious rings,

which become red-and-white or red-and-yellow.

Conditions:

Important reservoirs of the virus include weed species and perennial ornamentals. Natur al spreadin the field is caused only by thrips, in a persistent manner.

Control:

1. Using reflective mulches under tomatoes2. Elimination of thrips and host plants

3. Tomato field should be located as far away as possible from flower or grain fields, and homegardens

4. Apply the systemic insecticides

IV. Root-knot nematode (Meloidozyne incognita)

Symptoms:

The root-knot nematode is a minute roundworm which causes galls on tomato roots. These galls

may vary in size from pinhead to over 3 cm in diameter. The first above ground symptoms are a

stunting, wilting and generally off-colored appearance of the plant. Often, whole areas in a field

are affected. When diseased plants are pulled up, the irregular swellings of the root and gall

formation can easily be seen.

Conditions:

Nematodes are more severe in areas where on lighter, sandier soils. The host range of the root

knot nematode is very wide with many crops and weeds begin susceptible. Moderate soiltemperatures of 16°C to 27°C favor development of the nematode. Spread of the nematode may

occur from infected plants, farm machinery and irrigation water.

20

Control:

Once a field is infected, it is virtually impossible to eliminate the nematode.1. Using resistant cultivars provides the most effective control2. Resistant cultivars are not used economic control depends on

1) Preventing introduction of infected transplants or infested soil.2) Rotating with non-host crops, such as corn, wheat, and rice.3) Steam or chemical treatment of soil.

4) Successive deep plowing during hot weather to desiccate the nematodes.

V. Insects:

1. Fruitworm (Helicoverpa a.rmigera)

The fruitworm attacks fruit in all stages of development. The fruits are spoiled by feeding marks

(small or deep holes). The female is active at night and lays her eggs singly on the sepals of flowersor young fruits. The newly hatched larvae are dark-gray and feed on the flowers or fruits. Older

leaves vary in color from brown to green and have a characteristic yellow strip on either side of

the body. Since indeterminate varieties have fruits at various stages of maturity during a large

part of the season, they are generally more exposed to damage by fruitworm.

Control:

To control, begin spraying after first fruit set and repeat every 7 to 10 day with alternate

application of Lannate (methomyl 0.25 kg a.i./ha), Decis (deltamethrin 0.05 kg a.i./ha) and

Orthene (acephate 0.25 kg a.i./ha). Stop spraying 14 days before harvest.

2. Aphids (Aphidoidea)

No aphids are host-specific for tomato. Consequently, wherever tomatoes are cultivated they may

be aKacked by the local aphids. Aphids are green or gray body, length varying from 1 to 2 mm

long, winged or wingless insects, and found in small colonies on the underside surface of the

leaves and on young shoots. They feed mainly by sucking the sap from phloem tissue. They can

interfere with growth when they drain too much of the plants ' food resources. The most severe

damage, however, is caused by transmitting virus diseases, which occurs even with rather lowaphid population.

Control:

Begin spraying with Tokuthion (prothiophos 0.5 kg a.i./ha), Dimethoate (0.5 kg a.i./ha) Or

Decis (deltamethrin 0.05 kg a.i./ha) once a week until infestation last. Care must be taken to

spray the undersides of leaves to ensure proper coverage. Stop spraying 14 days before harvest.

3. Leafminers (Agromyzidae)

The adult fly is small, about 2 mm long, grayish-black with yellow to pale-yellow spots on the

thorax. Occasionally with a metallic sheen. The egg is 0.1-0.2 min long, pale in colour, and insertedsingle into the leaf tissue. The larva is legless, without a distinct head capsule. When fully grown

the larva is about 3 mm long. It usually pupates exterorably, mainly in the soil and sometimes on

the leaf surface. Leafminers have a rather short generation time; about two weeks from egg to egg

21

most severe damage, however, is caused by transmitting virus diseases, which occurs even with

rather low aphid population.

Control:

Begin spraying with Tokuthion (prothiophos 0.5 kg a.i./ha), Dimethoate (0.5 kg a.i./ha) orDecis (deltamethrin 0.05 kg a.i./ha) once a week until infestation last. Care must be taken to

spray the undersides of leaves to ensure proper coverage. Stop -praying 14 days before harvest.

3. Leafminers (Agromyzidae)

The adult fly is small, about 2 mm long, grayish-black with yellow to pale-yellow spots on the

thorax. Occasionally with a metallic sheen. The egg is 0.1-0.2 mm long, pale in colour, and inserted

single into the leaf tissue. The larva is legless, without a distinct head capsule. When fully grown

the larva is about 3 mm long. It usually pupates exterorably, mainly in the soil and sometimes on

the leaf surface. Leafminers have a rather short generation time; about two weeks from egg to egg

in warm weather and they reproduce all year round. Its larva feed on the inner leaf tissue between

the two epidermal layers, causes desiccation, a resulting in premature wilting which often leads to

suncorch of the exposed fruit. it also reduces assimilation and mineral uptake.

Control:

1. normally controlled by natural occurring parasites

2. Apply a systemic organophosphorus fungicide such as Pyrazophos (Afugan)

3. The use of chemical applied as soil drenches aims to kill the fully grown larvae on their way to

pupate [ a mixture of polybutenes and an insecticide (thripstic)]

4. Whiteflies (Bemisiatabacilargentifolii)

The adult whitefly is both case in small (1-2 mm long) and winged. Its body colour is yellow but

appears white due to the waxy dust covering the body and the wings. The forewings are slightly

longer than the hind wings. At rest, the wings cover the abdomen like a roof. The eggs are elliptical

and elongated, attached vertically to the leaf surface by a short stalk which is inserted into the leaf

tissue. They are normally laid in a circle comprising 20-40 eggs, on the underside of the leaf. The

main damage is indirect - by transmitting tomato yellow leaf curl virus diseases.

Control:

1. Using plastic coverage

2. Adequate insecticidal sprays

3. Colour mulching and cultural measures

5. The following insecticides were used based on recommendations by AVRDC

entomologists.

22

Dosage (kg a.i./ha) Diluti

0.05 1:5000.5 1:10000.5 1:2000

0.1-0.2 1:5000

0.5 1:2000

(B) Nonparasitic disorders (Physiological diseases)

1. Blossom-End rot

Symptoms:

Diagnostic symptoms are light tan lesions turning to dark brown sunken areas at the blossom end

of the fruit. The lesion typically°enlarges and becomes more sunken and leathery accompanied by

dry rot. A black mold may grow on the surface of the lesion. Sometime there is an internal black

rot of tissue in the center of the fruit with little or no external symptoms. Fruit affected by blossom-

end rot ripens more rapidly than normal.

Cause:

Blossom-end rot often occurs during periods of luxuriant growth, periods of alternately high and

low soil moisture, and cause calcium deficiency. In general, any soil condition affecting the uptake

of calcium may result in this disorder. Other conditions, in addition t, moisture

stress, drought, excessive ammonium or potassium, and low pH, which could cause blossom-

end rot.

Control:

1. Proper fertilization and water control

2. Limiting with dolomitic or high-calcium limestone 2-4 months before planting.

3. Avoid excessive use of nitrogen, especially in ammonium form.

4. If calcium deficiencies or high salt occur during the growing season, foliar sprays of 0.4%

calcium chloride solution when the first fruits are about 2 cm in diameter.

2. Blotchy Ripening/Gray wall

Symptoms: ,

Symptoms are first observed as flattened, blotchy, brownish-gray areas that develop on green

fruit. As the fruit mature these blotchy areas remain gray or turn yellow, resulting in uneven

ripening. When the fruit is cut open, dark brown vascular tissue can be seen in the fruit wall.

Cause

Environmental factors which appear to be associated with this disorder are high nitrogen, low

potassium, high soil moisture, high humidity, temperature fluctuations, low light intensity and

soil compaction. In addition, certain bacteria, fungi and/or tomato mosaic virus are thought to

be involved in gray wall.

Insecticides n

a) 2.8% Decis (EC)b) 50% Tokuthion (EC)c) 90% Lannate (WP)

d) 75% trigard (WP)

e) 9.6% confidor (EC)

23

Control:

1. Use tolerant varieties2. Reduce amount of nitrogen and apply more potassium.

3. Don't irrigate too much water.

3. Cracking

Symptom s:

In concentric cracking the fruit: develop circular, concentric cracks around the stem end of the

fruit. In radial cracking the fruit cracks radiate from the stem end. Catface is expressed asmalformation and cracking of fruit at the blossom end, often exposing the lacules.

Cause:

1. Periods of very fast fruit growth and suddenly change in high temperature and high

moisture levels.

2 Initial fruit growth during a dry period followed by heavy rain or irrigations during

ripening

3. Wide differences in day and night temperatures

Control:

1. Use resistant varieties

2. Proper water management and proper turning to limit fruit exposure

3. A good nutritional program

4. Puffiness

Symptoms:

Fruit have an angular appearance and are light in weight. When the fruit are cut open the

locules are not well filled. Seed development is poor with locules having very few seeds . and

little gel.

Cause:

Environmental factors which may lead to poor seed set and gel formation are high temperature

(above 38°C) or low temperature (below 13°C), the use of fruit harmonies, and conditions of

drought or excessive water. Wide fluctuations in day and night temperature during fruit'set are

thought to induce puffiness in fruit. Excessive fertility, especially nitrogen, may lead to, or

accentuate puff development.

Control:

1. Avoid excessive nitrogen

2. Proper use of fruit set hormones

5. Sunscald

Symptoms:

The symptoms are white, shiny, blistered areas appears on the sides or top part of green tomato

24

fruit, which are suddenly exposed to the sun. This leathery area becomes sunken and is frequentlyovergrown by fungi.

Cause:

Fruit that are suddenly exposed to direct sunlight are likely to develop this disorder. Premature

loss of leaf cover due to foliage disease may lead to sunscald. Fruit exposed during pruning or

harvesting operations may also develop-sunscald. In hot, semi-arid area bush tomatoes, which

break open or flop over suddenly as the fruit load becomes heavier, are more prone to sunscald.

Control:

1. Care should be taken in harvesting and pruning so as to minimize sudden fruit exposure.

2. Good fungicide spray programs will help prevent sudden foliage loss.

3. Use resistant varieties.

4. Use bush or ground varieties:

5. Reserve two branches to produce more foliage cover in indeterminate type.

6. Catface

Symptoms:

Catfaced tomatoes are generally misshapen, with enlarged scars and holes in the blossom end of

the fruit. Sometimes, the fruit is'kid.ne:y shaped, with elongated blossom scars, but it can also be

distorted into other shapes. Cat facing also includes any enlargement or perforation of the blossom

scar, even if the fruit shape is normal.

Cause:

Cold weather-is one reason. The flowers are susceptible to blossom-end roughness due to the

cold about 3 weeks before anthesis. Pruning has also been shown to increase catfacing under

some conditions. High nitrogen can aggravate the problem.

Control:

1. Use resistant varieties

2. Heating to avoid low temperature in the greenhouse

7. Poor fruit setting:

Cause:

Under hot, dry conditions of the tropics, high temperatures above 32/23°C (day/night) are

determinate to fruit setting. The dropping of reproductive organs is a common occurrence at

these temperature.

Control:

1. It is best solved by using heat tolerant varieties.

2. Dipping or spraying with tomatotone (p-chloro-phenoxyacetic acid) at 15 ppm, or 2-4-D (2-

4-dichlorophenoxyacetic acid) at 10 ppm on soon--to-open flower buds or newly open

flowers may improve fruit set.

25