2014 Watermelon Disease Update

Fusarium Wilt

• Fusarium Wilt (Fusarium oxysporum f.sp. niveum)• Early season, soil borne, cool weather pathogen• Can be seed borne (more and more showing up in

greenhouses)• Control

• 5-7 year rotation• Resistant varieties/grafting• Planting Date• Controlling Nematodes helps• Quadris/Actigard• Proline Fungicide Labeled in 2014

Watermelon Fusarium Wilt Trials (inoculated)

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10

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90

100

3/25/2010 4/6/2010 4/18/2010

Proline Drench(3 floz)Proline Drench(5.7 floz)Quadris Drench(15.4 floz)Untreated

Fusarium wilt % incidence

0

10

20

30

40

50

60

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80

90

100

4/8/2013 4/18/2013 4/28/2013

Proline Drench(3 floz)

Quadris Drench(15.4 floz)

Untreated

2013 Berrien Co. Grower Trial (not inoculated)

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100 Proline (3 floz) drench

Proline (3 floz) drench + 2apps (5.7 floz) banded spray

Quadris (15.4 floz) drench

Quadris (15.4 floz) drench +2 apps (15.4floz) bandedsprayActigard (0.5 oz) banded atplant + 2 apps (.75 oz)

Untreated

Fusarium wilt % incidenceBare Ground Watermelons

2014 Watermelon FW Methods Trial (inoculated)

0

10

20

30

40

50

60

70

80

90

100

4/8/2014 4/15/2014 4/22/2014 4/29/2014 5/6/2014

Proline Drench (3 floz) atplant

Proline Banded Spray (5.7floz) at plant

Proline Drip applied (5.7floz) at plant + 2 apps

Proline Banded Spray (5.7floz) at plant+ 2 apps

Quadris Drench (15.5 floz)+ 2 apps

Untreated

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Fusarium wilt % incidence

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ab

bc

cd

Watermelon Grown on Plastic Mulch

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2014 Proline FW Methods Wilt Trial (inoculated)

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Yield Lb/A

Proline Drench (3 floz) atplant

Proline Drip applied (5.7floz) at plant + 2 apps

Proline Banded Spray (5.7floz) at plant+ 2 apps

Proline Banded Spray(5.7floz) at plant

Quadris Drench (15.5floz) +2 apps

Untreated

a-c

bc

c

c

ab

Watermelon Grown on Plastic Mulch

a-c

Fusarium Wilt

• Proline, Quadris and Actigard have activity against Fusarium Wilt• Proline longer residual control than Quadris• Typically do not see phytotoxicity

• Application Method• At plant drench most effective • Not labeled for Pre-plant application

• Worker Safety Issues• Banded Spray has worked on bare ground watermelons• Banded spray application on plastic mulch not as effective (Multiple

applications better)• Drip applied may work but probably need multiple applications

(2wk) interval

Gummy Stem Blight

• Gummy Stem Blight (Didymella bryoniae)• Mid-Late season, Warm Weather, Foliar Pathogen• Driver of Fungicide spray program on Watermelons• Fungicides very effective against Gummy Stem Blight• Resistance Management Critical

Gummy Stem Blight

• Spray Chlorothalonil Products Early Season

• Late Season Fungicides (Resistance Management is Critical)• Luna Experence (Floupyram + Tebuconazole)• Inspire Super (Difenoconazole + Cyprodinil)• Proline (Prothioconazole)• Folicur + Generics (Tebuconazole)• Switch (Fludioxonil + Cyprodinil)

Triazole insensitivity toGummy Stem Blight

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LunaExperience

(10 floz)

InspireSuper

(20 floz)

Bravo(3 pt)

Switch(14 oz)

Tebuzol(8 floz)

Proline(5.7 floz)

Untreated

2013Attapulgus

2014VORC

2014Attapulgus

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a

c-e ab

fefef #

c c

Gummy Stem Blight AUDPC

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c

bc

ab

2014 Gummy Stem Blight Trial Locations

Gummy Stem Fungicide Rotations

• Luna Experience/ Inspire super rotation GOOD• Tebuconazole or Proline/Luna OK, • Tebuconazole or Proline/Inspire super OK• Switch rotation GOOD (Expensive)• Tebuconazole/Proline (BAD)• Tebuconazole/Tebuconazole (Very Bad)

Powdery Mildew

• Late Season Warm Weather Pathogen. Favors Dry Conditions.

• Pathogen harder to see on watermelon leaves• Apply Fungicides at fruit set• 2014 Reduced efficacy in the SDHI fungicides

2013, 2014 UGA Powdery Mildew Fungicide Trials

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20132014

Summer Squash Powdery Mildew Trials

Area Under Disease Progress Curve

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b

a

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a

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aba

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Powdery Mildew Fungicides

• Rotate Torino, Quintec, Proline or Procure• Reduced Efficacy of SDHI (Group 7) Fungicides in 2013

and 2014 (Luna Experience, Fontelis, Pristine)

2014 Disease Management Update

• Summary

• Tebuconazole resistance has been found in Gummy Stem Blight. Resistance management is critical. • Do not spray Tebuconazole back to back• Do Not Rotate Tebuconazole with Proline

• All of the SDHI Fungicides show lower efficacy for control of Powdery Mildew on Cucurbit Crops (Luna Experience, Fontelis, Pristine, Merivon)