nunhems netherlands bv leek diseasesfile/aus_lel_diseases.pdf · nunhems netherlands bv ... •...

Leek DiseasesShort description of the most important field diseases

Nunhems Netherlands BVPO Box 4005 | 6080 AA Haelen | The Netherlands

Tél. : +31 (0) 475-599222 | Fax +31 (0) 475-595104E-mail : [email protected]

Advice for cultivation practiceInformation provided by Nunhems Netherlands BV in any form whatsoever is without guarantee. Descriptions, recommendations, and illustrations in brochures and leaflets and on the website are based as closely as possible on experiences in tests and in practice. However, Nunhems Netherlands BV does not accept any liability whatsoever on the basis of such information for different results in the cultivated product. The buyer itself must determine whether the goods and information are suitable for the intended growth and/or can be used in the local conditions.

Product illustrationsAll varieties shown were grown under favorable conditions. Identical results are not guaranteed nor implied for all growing conditions.

© Nunhems BV, 2016. All rights, including property rights, are reserved by Nunhems BV or its affiliates on any matter presented or depicted herein.

The texts and pictures in this booklet are intended to help the grower identify plant diseases that affect their crops. The information herein is based on general observations. The pictures might give a distorted image of reality. This booklet was compiled with all relevant information available to Nunhems at the time of compilation. The information in this booklet is not to be considered as advice or a recommendation. Nunhems in no event accepts any liability on the basis of the information or pictures in this booklet.

Leek Diseases

Contents02 Alternaria Porri03 Puccinia Allii04 Fusarium Culmorum05 Phytophthora Porri06 Stemphylium Botryosum07 Cladosporium Allii Porri08 Colletotrichum. Circinans09 Sclerotium Cepivorum10 Pseudomonas Syringae11 Erwinia Carotovora12 Acrolepiopsis Assectella

(Leek moth)13 Delia Antiqua (Onion Fly)

14 Thrips Tabaci15 Napomyza gymnostoma

(Leek leafminer)16 Aphids17 Spider mite.18 Brown shaft stripes19 Herbicide Burning20 Nematodes (Meloidogyne

spp, Pratylenchus spp, paratrichodorus spp, trichodorus spp)

21 Yellow stripe virus

ALTERNARIA PORRI

English : Alternaria Porri

Occurrence :• Warm and wet conditions ; persistent rains• Herbicide damage

Symptoms :• Foliar disease : White purple spots• Leave will crack at damage• Affecting leaves will die

To prevent :• Use good soils• Preventive use of fungicides• Frequently scout the field for symptoms

3Leek Diseases

FUSARIUM CULMORUM

English : Fusarium Culmorum

Occurrence :• Unstable growth of the crop• Interruption of growth in the first weeks of the plant• Old plants 1415 weeks• To high EC and to low PH levels

Symptoms :• Red purple coloured shaft• Brown coloured root plate• Discoloration in the length direction of the leaf

PUCCINIA ALLI (RUST)

English : Puccinia Alli (Rust)

Occurrence :• Sunny day with temperatures above

15 degrees• Warm and wet conditions ; persistent rains• High humidity

Symptoms :• Small heaps (patches) of orange spots

on the leafs

To prevent :• Use healthy plant material• Crop rotation• Remove crop waste from field• Preventive use of fungicides

To prevent :• Be careful with organic matter specially the

time of application. At least 8 weeks before planting

• No disturbance in growth• Prevent of union fly on plants fields

4 Leek Diseases4 Leek Diseases 5Leek Diseases

STEMPHYLIUM BORTRYSOSUM

English : Stemphylium bortrysosum

Occurrence :• Disease survives on dry leaves• Unstable growth of the crop• Wear and tear disease

Symptoms :• Small white spots on the leafs• Sharped contours of yellow brown spots

PYTOPHTHORA PORRI

English : Pytophthora Porri

Occurrence :• No crop rotation• Hail and leaf damage• Day temperatures above 8 degrees• Humid and wet conditions

Symptoms :• White and dead leaf points• White spots with dark green contour on leafs

and shaf

To prevent :• Spray after rain and hail showers• Stable growth of the crop• Good drainage system

To prevent :• Harvest on time• Vital crop


COLLETOTRICHUM CIRCINANS

English : Colletotrichum circinans

Occurrence :• Warm and wet conditions• Splashing of raindrops can transfer the disease

from soil to shaft/leaf

Symptoms :• Irregular white spots were the shaft/leafs and

soils come together• In wet conditions black dots can occur in the

white spots• Sharped contours of yellow brown spots

CLADOSPORIUM PORRI

English : Cladosporium porri

Occurrence :• In between the 9 and 12 degrees in combination

with wet conditions• In Autumn it can occur together with Alternaria• When the crop closes the field

Symptoms :• Small oval spots on the leafs• The heart of the spot is coloured dark green/

brown with

To prevent :• Scout the field• When disease occurs spray

immediately fungicide

To prevent :• Extensive crop rotation


PSEUDOMONAS SYRINGAE

English : Pseudomonas Syringae

Occurrence :• Low crop rotation• Warm and wet conditions ; persistent rains• Carried along in plants

Symptoms :• Yellow leaf contour• Distortion of the leaf• Brown and wets spots on the leaf• Setback spots of growth in crop

SCLEROTIUM CEPIVORUM

English : Sclerotium Cepivorum

Occurrence :• Soil borne disease• Wet soils• High pH

Symptoms :• White fungi tissue on the root plate with

blackpinned Sclerotium spots

To prevent :• Extensive crop rotation• When soil is affected the advice is not to

grow leek on affected fields

To prevent :• Avoid leaf damage• Healthy plant material• Good crop rotation• Not possible to prevent with crop protection

011Leek Diseases010 Leek Diseases010 Leek Diseases10 Leek Diseases10 Leek Diseases 11Leek Diseases

ACROLEPIOPSIS ASSECTELLA

English : Acrolepiopsis Assectella (leek moth)

Occurrence :• First attack from half of may• Two or three flights per season

Symptoms :• Leek moth lays eggs around root plate• Larvae’s eat from the root plate in to the direction

of the heart of the plant• Yellow and green larvae’s inside the shaft

ERWINIA CAROTOVORA

English : Erwinia Carotovora

Occurrence :• Warm and humid conditions• Secondary disease usually after infection of

Pseudonomas or Delia Antiqua

Symptoms :• Infected plants have setback in growth• Distortion and fading of the plant• Infected plants give a smelly odour

To prevent :• Avoid plant damage• No irrigation when plants are infected

To prevent :• Regularly scouting of the field• Placing of pheromone traps• Spray of insecticide


THRIPS TABACI

English : Thrips Tabaci

Occurrence :• First development of dry and warm weather

Symptoms :• Adult thrips are dark brown• Larvae in between shaft and leaf• Damage of the larvae on the leaves are

silverwhite spots

DELIA ANTIQUA

English : Delia Antiqua (Onion fly)

Occurrence :• Every moment after drilling or transplanting

Symptoms :• White maggots at base of the plant.

Sometime also in the heart of the plant• Leaves will be yellow and plant will wither

To prevent :• More risk of infection of fields out of the wind• Spray of insecticide

To prevent :• Clean plant material• Scout the field• Start with spaying when you see the first

larvae or adult insect


APHIDS

English : Aphids

Occurrence :• Rare plague in the cultivation of leek

Symptoms :• Visible on young leaves• Aphids excrete honeydew and allure fungi• Aphids can transfer other diseases like yellow

stripe virus

NAPOMYZA GYMNOSTOMA

English : Napomyza gymnostoma (leek leaf miner)

Occurrence :• Two generations. One in April – May. Second

one in Sept – Nov.

Symptoms :• Larvea makes corridors in the length direction

of the plant• Oxidation makes red colouring of the corridors• Symptoms looks similar to red stripes

To prevent :• Scout the field• Sticky traps• Spray with insecticide

To prevent :• Scout the field• Spray with insecticide• Irrigation can flush away the Aphids

017Leek Diseases016 Leek Diseases016 Leek DiseasesSource Christian Rhoné - Bayer


BROWN SHAFT STRIPES

English : Brown shaft stripes

Occurrence :• Explosive unstable growth after transplanting

due to combination of fertilizers and high soil temperatures

• Usually on sandy soils

Symptoms :• Cells collapse and create red/brown stripes

SPIDER MITE

English : Spider mite

Occurrence :• Rare plague in the cultivation of leek• High temperatures. Optimum development

stage is 30 32 degrees and long dry periods

Symptoms :• White dots on the leaves. Looks like thrips

damage.• Aphids excrete honeydew and allure fungi• Aphids can transfer other diseases like yellow

stripe virus

To prevent :• Scout the field• Spray with insecticide

To prevent :• Stable growth• Controlled applying of fertilizer


NEMATODES (Meloidogyne spp, Pratylenchus spp, paratrichodorus spp, trichodorus spp)

English : Nematodes

Occurrence :• Wet conditions of the soil• Sandy and silty soils

Symptoms :• Root rot• Knobby roots• Roots makes side shoots

HERBICIDE BURNING

English : Herbicide burning

Occurrence :• Double appliance of chemical. Overlap

Symptoms :• Dying of the leafs• Weak crop and more susceptible

for fungicides• Lost yield

To prevent :• No overlap• Follow guidelines of the label• Mechanical weeding

To prevent :• Each nematode has it’s specific action• Growing of Tagetes patula• Control of weeds• Control your pH level


YELLOW STRIPE VIRUS

English : Yellow stripe virus

Occurrence :• Aphids are the host of the virus and can

transfer it over to the leek• Cold weather develop the disease

Symptoms :• Yellow stripe that runs along with the leaf vein

To prevent :• Spray insecticide• Continuous growth

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NOTES

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