spray rig (design evaluation)... · spray rig (design evaluation) figure 1. a spray rig operates...

1

Strawberry Center Field Day, Cal Poly San Luis Obispo – 18 July 2019

Spray Rig (design evaluation)

Figure 1. A spray rig operates with nozzles at canopy level to increase uniformity and coverage.

Figure 2. An operator verifies that the application rates of similar nozzles are equal.

Preliminary results of rig evaluations across Watsonville, Salinas, Santa Maria, and Oxnard indicate that operating spray rigs with nozzles at or below canopy level (see Fig. 1) increases distribution uniformity and overall spray coverage. This is irrespective of rig configuration. Furthermore, results suggest that operating nozzles at pressures above 100 psi and spacing them so that their particle trajectories do not overlap contributes to improved performance.

*Evaluations were performed with the use of water-sensitive paper and water-soluble solution

Spray Rig (calibration and maintenance)

Spray rig calibration is an essential component to ensuring a uniform application. The California Strawberry Commission has developed a standard operating procedure and training tools in English & Spanish for companies to verify that their spray equipment functions as it should (see Fig. 2). Employees responsible for spray equipment & applications must:

1) Ensure that hoses, nozzles, filters and other components are intact and clean, and that regulators and gauges function properly.

2) Perform routine maintenance before, during and after an application to fix clogs and leaks across the system.

3) Identify the correct pressure, flow & speed adjustments per tractor to achieve a desired application rate.

1


Lygus Bug Vacuum Optimization

Figure 1. A 2nd generation vacuum operates at canopy level to increase Lygus bug removal. For comparison, a conventional (yellow) vacuum is shown on the left.

Figure 2. The baffles used to eliminate Lygus bug are shown in an elevated position. Safety guards have been removed for the purpose of this photo.

The 2nd generation Lygus bug vacuum utilizes three fans with three straight tubes per 64-inch bed. The three 18-inch fans cover an area twice that of a conventional C&N vacuum while maintaining average wind speeds of 50 mph. The bug vacuum should be placed as close to the plant canopy as possible without causing damage to the crop (see Fig. 1). The recommended driving speed for the bug vacuum is 2.0 mph. Under these operating conditions, an average of 2.3 times more Lygus was shown to be removed compared to the conventional C&N vacuum. The new system can be installed on current C&N machines without major modification.

Please note that a new baffle design is used. The design utilizes standard 22-degree perforated louvres raised six inches off the outlet (see Fig. 2). This modification reduces backflow, increases windspeeds by 20 mph and maintains a Lygus kill rate greater than 95%.


1 FRAC = Fungicide Resistance Action Committee; numbers represent distinct fungicide modes of action; M = multi-site inhibitors; NC = not classified. 2 Efficacy rating: (--) ineffective, (+) low efficacy, (++) moderate efficacy, (+++) good efficacy, (++++) high efficacy. 3 Resistance status: (n) not determined, (--) no resistance, (*) low resistance, (**) moderate resistance, (***) high resistance 4 UC = Efficacy ratings are presented from Adaskaveg, J.A., et al. 2017. University of California Statewide IPM Program, https://www2.ipm.ucanr.edu/agriculture/strawberry/Fungicide-Efficacy/ . 5 NR = not registered. 6 EPA registered, California registration pending.

Table. Comparison of fungicide efficacy and fungicide resistance status generated from the Cal Poly Strawberry Center Botrytis fruit rot efficacy trials. Results are compiled from 11 trials over a 6-year period. The grower standard (Switch 62.5 WG 14oz/A rotated with Captan 80 WG 3lb/A) reduced Botrytis fruit rot by an average of 43%. The most effective fungicides replicated over multiple years were Kenja 400 SC, Switch 62.5 WG and Merivon 42.5 SC, reducing Botrytis fruit rot by 57% - 80%.

Trade name Active ingredients FRAC code1

Efficacy rating2

Resistance status3

No. exp’ts

Con

vent

iona

l

Topsin, Incognito thiophanate-methyl 1 +++ *** UC4

Kenja isofetamid 7 ++++ * 7 Fontelis penthiopyrad 7 +++ ** 2

Scala pyrimethanil 9 + n 1 Abound azoxystrobin 11 + *** 2

Evito fluoxastrobin 11 + *** UC Intuity mandestrobin 11 + *** 3 Cabrio pyraclostrobin 11 ++ *** UC Flint trifloxystrobin 11 + *** 1

Elevate fenhexamid 17 +++ *** 4 Ph-D, Oso polyoxin D zinc salt 19 ++ n UC

Thiram thiram M3 + -- 6 Captan captan M4 + -- 16

Luna Sensation fluopyram + trifloxystrobin 7 11 +++ * *** 2 Merivon fluxapyroxad + pyraclostrobin 7 11 ++++ ** *** 4 Pristine boscalid + pyraclostrobin 7 11 +++ ** *** 1

Luna Tranquility fluopyram + pyrimethanil 7 9 ++ * n 1 Switch fludioxonil + cyprodinil 12 9 ++++ * ** 11

CaptEvate captan + fenhexamid M4 17 +++ -- *** UC

♦O

rgan

ic ♦

Aviv Bacillus subtilis strain IAB/BS03 44 -- -- 1 Serenade ASO Bacillus subtilis strain QST 713 44 -- -- 3 Double Nickel Bacillus amyloliquefaciens strain D747 44 -- -- UC

Actinovate Streptomyces lydicus WYEC 108 NC -- -- 4 Procidic citric acid NC -- -- 4 Regalia extract of Reynoutria sachalinensis P05 -- -- 2

Veg’Lys/Aleo garlic oil NC -- -- 1

NR

5

Bacillus amyloliquefaciens strain F727 44 -- -- 8 pyraziflumid pyraziflumid 7 +++ n 2

Miravis Prime6 fludioxonil + pydiflumetofen 12 7 ++++ * n 4 ♦ Rango6 cold pressure neem oil NC + -- 1

2

♦ Stargus6

https://www2.ipm.ucanr.edu/agriculture/strawberry/Fungicide-Efficacy/

♦ = Organic products; ᴺᴿ = Not registered; / = Weekly rotation; DAFA = Days after final application; DAH = Days after harvest.¹Rotation sequence of Elevate, Kenja, Switch, Merivon, Switch (at max labeled rate); each tank mixed with Captan 80WDG (3 lb/A).²Half rate of Switch (7 fl oz/A) rotated with half rate of Captan 80 WDG (1.5 lb/A) and tank mixed with Confidential 1.³Rotation sequence of Confidential 3 (C3), Kenja, Switch, Merivon, C3 (at max labeled rate); each tank mixed with Thiram SC (2.6 qt/A)

Field evaluation 1 DAFA Postharvest evaluation 7 DAH Field evaluation 1 DAFA Postharvest evaluation 7 DAH

56.3

62.5

73.4

72.7

78.9

39.8

58.6

73.4

75.8

68.8

71.1

68.0

60.2

59.4

78.9

37.5

76.6

46.9

4.8

4.6

4.3

3.8

3.3

3.2

3.0

2.9

2.9

2.6

2.6

2.2

2.2

1.7

1.6

1.5

1.5

1.0

0 10 20 30 40 50 60 70 80 90 100

♦VBC-80171 ᴺᴿ 6.5 lb

♦VBC-80212 ᴺᴿ 2.84 lb

♦VBC-80212 ᴺᴿ 1.42 lb

♦VBC-80212 ᴺᴿ 5.7 lb / Serenade Optimum 20 oz

Non-Treated

C3-K-S-M-C3 Rotation ³

♦HDB 1000 ᴺᴿ 4 lb

Thiram SC 2.6 qt

♦HDB 1000 ᴺᴿ 12 lb

♦VBC-80171 ᴺᴿ 1.62 lb

♦VBC-80171 ᴺᴿ 3.24 lb

Confidential 3

Captan 80 WDG 3 lb

Switch 14 oz /Captan 80 WDG 3 lb

♦AMV4005 35 fl oz

E-K-S-M-S Rotation¹

♦AMV4007 35 fl oz

Switch 14 oz /Confidential 3

Gray mold incidence (%)

Summer 2019

AB

AB

AB

B

AB

AB

AB

AB

AB

AB

AB

AB

AB

AB

B-E

ABC

ABC

AB

AB

AB

AB

A-E

DE

AB

AB

91.8

95.3

95.3

89.8

90.6

87.5

85.2

88.3

65.6

39.8

64.1

85.9

82.8

82.8

68.0

67.5

61.7

12.6

10.7

10.5

9.8

9.0

8.3

6.1

5.4

3.6

3.5

3.4

3.3

2.8

2.6

2.5

2.1

0.9

0 10 20 30 40 50 60 70 80 90 100

♦Regalia 2 qt/ Stargus ᴺᴿ 2 qt

♦Veg'Lys 12 fl oz

Non-Treated

♦Confidential 1 ᴺᴿ

Captan 80 WDG 3 lb

♦Procidic 20 fl oz

♦RXORG 14 ᴺᴿ 1 qt

♦Confidential 2 ᴺᴿ

Confidential 1 Mix² ᴺᴿ

Miravis Prime ᴺᴿ 13.4 fl oz

Kenja 13.5 fl oz

Switch 8 oz/Stargus ᴺᴿ 1 qt

Pyraziflumid ᴺᴿ 3 fl oz

Switch 8 oz/Stargus ᴺᴿ 2 qt

Switch 14 oz/Captan 80 WDG 3 lb

E-K-S-M-S Rotation¹

Kenja 15.5 fl oz

Gray mold incidence (%)

Spring 2019

ABC

AB

A

B

C

EF

DEF

DEF

A-D

C-F

AB

AB

B

B

B

B

C

CD

CD

CD

CD

CD

D

D

EF

F

A

ABC

AB

AB

AB

B-E

AB

A

AB

AB

CDE

AB

E

A

A-D

A-D

Fungicide Efficacy Against Botrytis Gray Mold (cv. Monterey)

AB

Spring 2019. 5 applications made at 7-day intervals (12 Mar to 11 Apr). Harvest was on 12 Apr. Total rain accumulation, 2.7 in.

Summer 2019. 5 applications made at 7-day intervals (30 Apr to 30 May). Harvest was on 31 May. Total rain/micro sprinklers accumulation, 2.1 in.

CD

CD

Sorted by level of gray mold present at field evaluation. Data was subject to ANOVA and Fishers LSD mean separation. Error bars represent standard error of the mean. Means that do not share the same letter are significantly different (α=0.05).

2

The Effect of Pre-plant Fertilizer Management on Four Strawberry Cultivars

Kamille Garcia-Brucher; Graduate Student, Horticulture and Crop Science Dep’tCharlotte Decock; Natural Resources Management and Environmental Science Dep’t

BackgroundImproving nitrogen (N) management in California strawberry production is warranted due to rising environmental concerns and legislative restrictions. Controlled release fertilizers (CRFs) are commonly applied in the fall before planting with the expectation of long-term release of nutrients during winter plant establishment. A recent study from the UC Cooperative Extension shows that CRF N is released before plant N uptake, suggesting that CRF is an ineffective source of nutrients for the crop. Compost might be a viable substitute for early season nutrient delivery to strawberry crops because composts are known to have slower nutrient release patterns than CRFs. However, compost also holds the risk of competing with the plant by temporarily immobilizing nitrogen. Besides effects of compost on nitrogen dynamics, they have been shown to suppress disease by soil borne pathogens in certain cases, but have no effect or even increase disease incidence in other cases. Given incentives by the State of California to increase compost application to agricultural land to protect soil fertility and decrease greenhouse gas emissions, further research is needed to assess the suitability of the use of compost in strawberry production. A field experiment at California Polytechnic State University’s Strawberry Center began in Sep 2018 to observe soil and plant N dynamics and disease incidence of Macrophomina phaseolina by comparing three pre-plant fertilizer strategies among four strawberry cultivars.

Mt. Bishop Rd

Experimental Design

CRF

Compost

Control

Pre-plant Management (100 lb. N/acre)

1. Monterey2. San Andreas3. Albion4. Proprietary

Cultivars

Figure 1. Field experiment design.

• Impending legislation, Ag Order 4.0, will not only require growers to report their N input to their strawberry productionsystem but will also require growers to reduce N waste discharge to 50 lb./ac/ranch/yr by 2050.

• The Regional Water Quality Control Board (RWQCB) requires all synthetic N applications to be reported but may onlyrequire some of compost N applications to be reported as N in compost is organically bound and mineralization rates areunpredictable.

• As part of former Governor Brown’s Healthy Soils Initiative, the California Department of Food and Agriculture establisheda financial incentive program for California’s farmers and ranchers to implement practices that improve soil health and reducegreenhouse gas emissions.

• Application rates of 2.2 to 3.6 dry tons/acre for compost with a C:N ratio lower than 11 and rates of 4.0-5.3 dry tons/acre forcompost with a C:N ratio greater than 11 have been incentivized, at a payment rate of $35/dry ton.

• For more information on the Healthy Soils Initiative, visit: https://www.cdfa.ca.gov/oefi/healthysoils/

Why Compost?

Strawberry Center Field Day, Cal Poly San Luis Obispo - 18 July 2019

Fig. 1

Bishop Peak

Tech Park

Measurements• Soil N availability

in/below root zone• Plant N uptake• Plant C:N• Plant biomass• Microbial activity• Yield• Disease incidence

3

0

1000

2000

3000

4000

5000

Monterey San Andreas Albion Proprietary

Yie

ld (t

rays

/Ac)

0

50

100

150

200

250

300

Monterey San Andreas Albion Proprietary

AU

DPC

(%-d

evel

opm

ent u

nit)

Compost

Control

CRF

Strawberry Center Field Day, Cal Poly San Luis Obispo - 18 July 2019

Preliminary Results and Conclusions

Figure 3. Disease incidence by Macrophominacrown rot in compost, control and CRF management plots (A, B, and C respectively) from 13 May 2019 to 5 July 2019. Area under disease progress curve (AUDPC; D) results suggest cultivar has a strong effect on disease incidence and pre-plant management does not.

Figure 2. Marketable yield data from 1 April to 5 July 2019. Unmarketable fruit was subtracted from total yield based on observations monthly. Yield results show cultivar type has a strong effect on yield and pre-plant management does not.

Macrophomina Disease ProgressFig. 3

0

10

20

30

40

5/13 5/27 6/10 6/24 7/8

CompostA

0

10

20

30

40

5/13 5/27 6/10 6/24 7/8

ControlB

0

10

20

30

40

5/13 5/27 6/10 6/24 7/8

CRFC

Marketable Yield as of 5 July 2019Fig. 2

Management: n.s. (p= 0.5092)Cultivar: sig (p<0.0001)Management x Cultivar: n.s (p= 0.3565)*n.s.= not significant, sig= significant atp<0.05 level*Means followed by the same letter arenot significantly different

Dis

ease

inci

denc

e by

M

acro

phom

ina

crow

n ro

t (%

)

Management: n.s. (p= 0.2023)Cultivar: sig (p<0.0001)Management x Cultivar: n.s (p= 0.6028)*n.s.= not significant, sig= significant atp<0.05 level*Means followed by the same letter arenot significantly different

D

Compost Control CRF

ProprietarySan Andreas AlbionMonterey

BCB

A

C

BC

AB

C

A

• Compost can safely be applied to strawberry fields as a substitute for synthetic pre-plant CRF without decreasing yieldor increasing disease incidence

• Even though Monterey has relatively high disease incidence, its yield was still the greatest among the four cultivarstested

• Determination of N uptake curves for cultivars and assessment of the effect of pre-plant fertilizer management on plantavailable N levels and soil health are ongoing.

• This data will inform strategies to advance the sustainability of strawberry production without reducing yield.

Conclusion

3


Evaluating Host Resistance to Macrophomina Crown Rot in Strawberry - 2019

S. M. Mansouripour, K. A. Blauer & G. J. Holmes

In the fall of 2018, our third consecutive field trial was established to evaluate 83 strawberry cultivars and elite selections for resistance to crown rot caused by Macrophomina phaseolina. Strawberry germplasm was selected from six breeding programs: University California Davis (UC), University of Florida (FL), Driscoll’s (DR), Plant Sciences (PSI/PE/BG), Planasa (PL) and Lassen Canyon (LC). The trial consisted of 20-plant plots replicated four times, with a fifth non-inoculated replicate. The non-inoculated area was flat-fumigated with Ally 33 (67% AITC + 33% chloropicrin at 55 gal/A) in the fall of 2018. On 23 Oct 2018, bare-root strawberry transplants were set in field 35b on the Cal Poly San Luis Obispo farm (Fig. 1). Two weeks later each plant in the inoculated replicates received 5 grams of cornmeal-sand-Macrophomina inoculum placed around the crown and root zone (Fig. 2A). Plants were drought stressed by withholding irrigation for 3 consecutive days per week starting 1 Jun. Presence of the pathogen in plants was confirmed by standard plating techniques. Disease assessments were conducted every four weeks, then every two weeks after the first symptoms appeared (30 May 19). Plants were considered dead when all foliage was necrotic.

Figure 1. Aerial view of Macrophomina host resistance trial located in field 35b on Cal Poly San Luis Obispo farm. Plants in the area outlined in red were inoculated; plants in the area outlined in yellow were not inoculated (control). (Photo taken on 29 June 2019)

Figure 2. A) Inoculating a transplant with M. phaseolina inoculum. B) Early wilt symptoms of crown rot (Plant circled in yellow). C) Cross section of a necrotic crown showing brown discoloration of the tissue due to M. phaseolina.

A B C

4


1.31.3

2.62.6

3.83.9

5.96.36.36.3

6.87.4

7.68.8

10.010.6

10.811.111.1

11.311.3

11.612.512.513.4

13.513.8

13.815.2

15.415.4

15.816.3

16.716.9

17.117.4

18.120.0

20.020.3

20.421.3

21.821.9

21.923.7

23.824.3

26.026.7

27.527.828.8

30.131.3

33.236.6

37.137.5

38.239.3

40.741.0

41.344.0

46.548.3

48.850.8

50.953.2

53.553.8

55.757.8

59.760.0

62.565.669.6

72.273.9

0 10 20 30 40 50 60 70 80 90 100

Marquis179AB165

LaredoUC-NLC-E

UC-MUC-GUC-ALC-C

BG 6.3024Osceola

UC-FPL 12-04R

PL 3002SensationFronterasFortalezaGrenada

UC-KPE 6.2036

PSI-H124AB74115AB55

PSI-BUC-I

MaverickBG 6.3016BG 9.3142

PL 3001Prado

UC-JWinterstar

BG 4.367UC-L

PS 9271Spartan

MaverickPetaluma

PSI-IPSI-C

Del ReyPSI-FPSI-D

Big SurAmado

MontereyFestivalPS 5016

UC-HCabrillo

PSI-KUC-D

PE 3.211LC-DLC-HLC-F

SanAndreasPL 09-55

UC-CPSI-ELC-GLC-B

BeautyAlbion

PSI-GRavinaPilgrim

PSI-APSI-J

PE 7.2059BrillianceRadiance

UC-EAlbion

PomonaEl Dorado

Sweet AnnKora

Ruby JuneOdessa

PL 05-100RUC-BLC-A

Plant Mortality (%)

Average percent mortality due to Macrophomina crown rot on 10 July 2019

4


1.31.3

2.66.8

10.811.6

12.513.5

15.417.1

17.420.3

21.821.9

44.046.5

55.757.8

60.065.6

3.86.3

28.830.1

31.338.2

39.359.7

62.573.9

7.68.8

15.236.6

69.66.3

11.311.3

12.513.8

13.816.3

16.920.0

20.020.4

21.323.8

26.727.8

37.541.3

48.348.8

50.82.6

3.95.9

6.37.4

10.611.111.1

13.415.4

16.718.1

21.924.3

26.027.5

33.237.141.0

53.553.8

72.210.0

15.823.7

40.750.9

53.2

0 10 20 30 40 50 60 70 80 90 100

Marquis179AB165

LaredoOsceola

Fortaleza124AB74115AB55

MarverickPrado

SpartanMarverick

Del ReyBig SurAmadoRavinaPilgrim

PomonaEl Dorado

KoraOdessa

LC-ELC-CLC-DLC-HLC-FLC-GLC-B

Sweet AnnRuby June

LC-APL 12-04R

PL 3002PL 3001

PL 09-55PL 05-100RBG 6.3024PE 6.2036

PSI-HPSI-B

BG 6.3016BG 9.3142

BG 3.324PS 9271

PSI-IPSI-CPSI-FPSI-D

PS 5016PSI-K

PE 3.211PSI-EPSI-GPSI-APSI-J

PE 7.2059UC-NUC-MUC-GUC-AUC-F

FronterasGrenada

UC-KUC-IUC-JUC-L

PetalumaMonterey

UC-HCabrillo

UC-DSanAndreas

UC-CAlbion

UC-EAlbion

UC-BSensation

WinterstarFestivalBeauty

BrillianceRadiance

Plant Mortality (%)

Average percent mortality due to Macrophomina crown rot (by breeding program) on 10 July 2019

University of Florida

Plant Sciences

Lassen Canyon

Driscoll’s

University of California

Planasa

Breeding program

4


0

200

400

600

800

1000

1200

1400

1600

1800

Num

ber

of d

ead

plan

ts

Date

Progress of Macrophomina crown rot2019

0

1

2

3

4

5

6

7

8

9

10

Oct Nov Dec Jan Feb March April May June

Prec

ipita

tion

(in)

Month

Precipitation

2019 2018

2018

4

Strawberry Center Entomology Program:


Pest mites:

Figure 1. (A) The twospotted spider mite, Tetranychus urticae Koch, and (B) Lewis spider mite, Eotetranychus lewisi (McGregor), are key pest mite species that attack CA strawberries. In general, the males of both species are similar in appearance while female twospotted spider mites have a single pair of large lateral spots compared with two or more lateral spots on the Lewis spider mite. Female twospotted mites are slightly larger than female Lewis mites.

A

Catfacing damage:

Figure 2. Catfacing damage to strawberries can be caused by (A) poor pollination (note small, undeveloped achenes (seeds)), or, (B) when lygus bugs feed on achenes of small, developing fruit (note full-sized achenes).

B

PW Shearer

A

PW Shearer

PW Shearer

B

PW ShearerPW Shearer PW Shearer

5

6


Cal Poly Strawberry Disease Diagnostic Service

How to Submit a Sample? Shashika S. Hewavitharana and Gerald Holmes

Instructions on how to properly collect, package, and deliver a strawberry plant sample

• Sample plants that show symptoms. It is harder to find the pathogens in dead plantmaterial because of all the other organisms present. Include 2-3 plants that show differentstages of the disease (mild to severe).

• If there are healthy plants of the same variety in the same bed or in the same area, sendone of them in a separate bag labelled ‘healthy’ for comparison.

• Send the entire plant. Even if you see symptoms in leaves, the pathogen can be infectingthe roots or crown. If you want to include soil with roots, bag the soil on roots in a smallplastic bag and secure with a tape/rubber band to avoid getting soil all over the plants andplace in another plastic bag (see the photo below). Please don’t send a large amount ofsoil.

Properly bagged sample

Too healthy Too decayed Just right

6


• Soil samples. Due to limited time and resources, we are unable to process soil samples atthis time. We can direct you to other diagnostic labs upon request.

• Take photos. It is helpful for us to diagnose the disease if you can send us photos of thesymptoms in the field before sampling showing the distribution of the problem in thefield. You can take photos with your phones and email those to us [email protected]

• Fill out the submission form. The plant disease problem submission form is now availableonline at https://strawberry.calpoly.edu/

o Each sample that has a different problem needs a separate form.o Provide as much information as you can. Information you provide helps us

diagnose the problem.• Submit your sample.

o Package your sample properly in a plastic bag. Do not use paper bags for leafsamples as these dry out quickly.

o Local samples: Drop off at the address below.• Ship your sample: Please ship the sample on the same day it was collected. If you are unable to ship the sample on the same day, store the bagged sample in the

refrigerator. Fresh samples are better for diagnosis. If possible use a cooler with ice packs during transit. Avoid direct sunlight on the

sample during transit. It is better to send us the samples early in the week. Please avoid shipping on Fridays

or before holidays. Label your package ‘perishable plants’. Shipping address:

Cal Poly Strawberry Center 1 Grand Ave. Technology Park Building 83, STE 1B San Luis Obispo, CA 93407

Monday-Friday 8:00 am – 4:30 pm

https://strawberry.calpoly.edu/


Fungicide Resistance Management in Strawberry Powdery Mildew M. Palmer, K. Blauer, G. Holmes

Table 1. List of fungicides currently labeled for use against powdery mildew in California strawberries

Product Active ingredient(s)

FRAC code* Risk of resistance development

Rally myclobutanil 3 resistance known in both strawberry and grape PM (Sombardier 2017 and Gubler 1996)

Quintec quinoxyfen 13 medium risk, resistance reported in grape PM

Fontelis penthiopyrad 7 medium to high risk

Luna Tranquility fluopyram, pyrimethanil

7, 9 medium to high risk

Merivon fluxapyroxad, pyraclostobin


Mettle tetraconazole 3 medium risk

Torino cyflufenamid U6 resistance reported in cucurbit PM (Pirondi 2015)

Luna Sensation fluopyram, trifloxystrobin


Abound/Quadris azoxystrobin 11 high risk

Flint trifloxystrobin 11 high risk

Sulfur sulfur M02 low risk, no signs of resistance development

* FRAC = Fungicide Resistance Action Committee; all active ingredients within a FRAC group are susceptible tocross resistance.

Resistance Management • FRAC Group 3 (DMIs; demethylation inhibitors)

o Use at full rateo Mix with effective, non-cross resistant fungicides (NOT QoIs)

• FRAC Group 7 (SDHIs; succinate dehydrogenase inhibitors)o Mixes should be with effective, non-Group 7 fungicideso If used alone, number of applications should not exceed 33% of total applications

per seasono If used in mixtures, SDHI should be no more than 50% of total applications per

seasono No consecutive (i.e., back-to-back) solo SDHI applications should be made and

never more than two consecutive SDHI mixes• FRAC Group 11 (QoIs; quinone outside inhibitors)

o Mixes should be with effective, non-Group 11 fungicideso Make no more than two applications per crop, preferably in mixture with non-

Group 11 partner

7


Current research on strawberry powdery mildew caused by Podosphaera aphanis

• Evaluation of fungicide efficacy against strawberry powdery mildew under greenhouseconditions, 2019

o Registered (e.g., Merivon) and unregistered (e.g., Gatten, pyraziflumid)fungicides applied five times to greenhouse plants inoculated with powderymildew

o Merivon and Gatten (6 and 8 oz/A) were the only products that significantlydiffered from untreated control two weeks after last spray

Figure 1. A) Powdery mildew on immature fruit; B) greenhouse set up for powdery mildew fungicide efficacy study; C) powdery mildew on mature strawberry leaves.

• Analysis of Fungicide Efficacy on Powdery Mildew on Strawberry in Californiao Commonly used fungicides (noted above) and Gatten will be evaluated for

efficacy on Podosphaera aphanis isolates collected from throughout the stateo Leaflets will be sprayed and inoculated, then evaluated for incidence and severityo Germination of spores will also be observed in gel amended with fungicideso If resistance detected, isolates will be genetically mapped in DNA regions where

resistance occurs

Figure 2. A) Podosphaera aphanis spores at 200X magnification; B) detached strawberry leaflets in front of fungicide suspensions used in fungicide resistance assay.

A B C

A B

7

Strawberry Center Field Day, Cal Poly San Luis Obispo—18 July 2019

Evaluation of Host Resistance to Anthracnose in Strawberry - 2019

O. Gonzalez-Benitez, M. Mansouripour, K. Blauer & G. Holmes

During the fall of 2018, we evaluated 76 strawberry cultivars and elite breeding lines for resistance to anthracnose caused by Colletotrichum acutatum. Strawberry germplasm was selected from six breeding programs: University of California, Davis (UC), University of Florida (FL), Driscoll's (DR), Plant Sciences (PSI/BG/PS/PE), Planasa (PL) and Lassen Canyon (LC). On 25 Oct 2018, bare-root strawberry transplants were transplanted in field 25 on the Cal Poly San Luis Obispo farm. The trial consisted of 10-plant inoculated plots replicated four times, with a fifth, non-inoculated control replicate. The field was flat fumigated with Ally 33 (67% AITC + 33% chloropicrin at 55 gal/A) prior to planting. Bare-root strawberry transplants were placed in a 1-gal plastic bag, mixed with 100 ml of C. acutatum inoculum (1 × 106 spores/ml) and shaken for one minute prior to planting. The first anthracnose symptoms were observed three weeks after planting. Presence of the pathogen on diseased plants was confirmed using Petri dish assays. Disease assessments were conducted weekly starting three weeks after planting (16 Nov 2018). Plants were considered dead when all foliage was necrotic.

Figure 1. Aerial photo of the anthracnose host resistance trial located in field 25 on the Cal Poly San Luis Obispo farm. The area outlined in red is the inoculated reps. The area outlined in yellow is the non-inoculated control. Both the red and yellow areas were fumigated with Ally 33 (67% AITC + 33% chloropicrin at 55 gal/A).

Figure 2.A) Petri dishes with strawberry plant petioles used for growth of Colletotrichum acutatum spores for inoculum; B) Bare-root transplants being inoculated on 25 October 2019 with C. acutatum inoculum; C) Strawberry plant showing symptoms of anthracnose on 15 April 2019; D) Strawberry fruit showing anthracnose fruit rot collected on 6 May 2019.

Field 25

Non-inoculated

Inoculated

DCB

A

8


2.52.5

10.012.5

15.015.0

15.818.620.0

22.522.5

22.523.6

25.025.8

30.030.6

32.532.5

35.035.0

35.037.537.5

39.239.4

42.544.4

46.947.5

53.654.7

55.055.0

56.456.4

57.560.0

60.061.7

62.565.0

65.066.4

66.767.5

67.970.0

70.070.0

71.471.7

74.475.0

76.977.577.5

78.179.4

79.781.782.584.7

86.487.5

89.489.7

90.092.5

94.495.0

97.5100.0100.0100.0100.0

0 10 20 30 40 50 60 70 80 90 100

PSI-10PS 5016

LC-1LC-4

UC-15Sensation

LC-5PE 7.2059

PSI-8LC-3

Prado179AB165

PE 3.211LC-2

BG 6.3016UC-1

UC-14LC-6LC-8

PSI-9BrillianceRadiance

PS 9271Sweet Ann

PSI-11PSI-7

BeautyUC-2UC-6

FronterasFestivalPL 3001

PSI-1UC-12

PSI-4San Andreas

Ruby JunePE 6.2036

WinterstarPSI-5

PL 09-55UC-3

OsceolaCabrillo

PSI-3PSI-2

PetalumaBG 9.3142

UC-8LC-7

BG 6.3024Del Rey

PSI-6UC-5

RavinaBG 3.324

Big SurUC-13

AmadoMaverick

PL 3002UC-11

PL 12-04RUC-7

PilgrimFortalezaEl Dorado

MarquisOdessa

UC-4Kora

LaredoUC-9

UC-10Monterey

Spartan

Plant mortality (%)

Average percent mortality due to anthracnose on 2 July 20198


22.522.5

65.071.7

76.977.5

79.479.7

87.589.489.7

90.092.5

95.097.5100.0

10.012.5

15.822.5

25.032.532.5

37.557.5

70.054.7

62.581.784.7

2.52.5

18.620.0

23.625.8

35.037.5

39.239.4

55.056.4

60.061.7

66.767.5

70.071.4

74.477.5

15.030.0

30.644.4

46.947.5

55.056.4

65.066.4

67.970.0

75.078.1

82.586.4

94.4100.0100.0100.0

15.035.0

35.042.5

53.660.0

0 10 20 30 40 50 60 70 80 90 100

Prado179AB165

OsceolaDel ReyRavinaBig SurAmado

MaverickPilgrim

FortalezaEl Dorado

MarquisOdessa

KoraLaredo

SpartanLC-1LC-4LC-5LC-3LC-2LC-6LC-8

Sweet AnnRuby June

LC-7PL 3001

PL 09-55PL 3002

PL 12-04RPSI-10

PS 5016PE 7.2059

PSI-8PE 3.211

BG 6.3016PSI-9

PS 9271PSI-11

PSI-7PSI-1PSI-4

PE 6.2036PSI-5PSI-3PSI-2

BG 9.3142BG 6.3024

PSI-6BG 3.324

UC-15UC-1

UC-14UC-2UC-6

FronterasUC-12

San AndreasUC-3

CabrilloPetaluma

UC-8UC-5

UC-13UC-11

UC-7UC-4UC-9

UC-10MontereySensationBrillianceRadiance

BeautyFestival

Winterstar

Plant Mortality (%)

Average percent mortality due to anthracnose on 2 July 2019 (sorted by breeding program)

Breeding programs

8

0

10

20

30

40

50

60

70

80

90

100

Plan

t Morta

lity

(%)

Date

Grouping of Mortality Trends

Figure 3. Plant mortality trends of 76 genotypes fell into five general categories: resistant (6 genotypes); moderately resistant (20 genotypes); moderately susceptible (late) (9 genotypes); moderately susceptible (14 genotypes); susceptible (27 genotypes).

susceptible

moderately susceptible (late)

resistant

moderately resistant

moderately susceptible

8

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