Foliar and Fruit Disease Management for Strawberries

Mark BoldaFarm Advisor, Strawberries and Caneberries

Santa Cruz, Monterey and San Benito Counties

Introduction

• Fruit and foliar pathogens of strawberry

Powdery mildew

Botrytis gray mold

Leather rot caused by Phytophthora spp.

Powdery mildew in strawberry

Conditions amenable to powdery mildew in strawberry

• Dry leaf surface, high relative humidity and cool to warm air temperatures.

• Spores are not long lived, mildew can come in on planting material or from neighboring fields.

Control of Powdery Mildew in Strawberries

• Selection of varieties

• Be on the alert during optimal conditions:

Ideal conditions for infection are dry leaf surfaces, high relative humidity, and cool to warm air temperatures (60 – 80oF)

• Sulfur

• Oils

• Synthetic fungicides

0

1

2

3

4

5

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7

8

9

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UTC Silmix 3qt

Orbit 4 floz

A1590914 fl oz

A7402 7fl oz

A1600114 fl oz

A1600120 fl oz

A1370314 fl oz

Rally 4oz

Procure 8fl oz

Procure +Thiram

Pinpoint0.03 lb airot/ GS

Pinpoint0.02 lb airot/ GS

Treatment 2008 Fungicide Screen

Mildew control of various materials

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2

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A1600

1 14 fl

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A1600

1 20 fl

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A1600

1 20 fl

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A1370

3 14 fl

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A1822

7 fl oz

Orbit 4

fl oz

A1590

9 14 fl

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Mettle

5 fl o

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Mettle

5 fl o

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GWN 4617

3.4 oz 1

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GWN 4617

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GWN 4617

3.4 oz r

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Leaf Problem #1

Leaf Problem #1

Leaf problem #2

Leaf problem #2

Leaf problem #3

Leaf problem #4

Leaf problem #4

Leaf problem #5

Leaf problem #5

Leaf problem #5

Botrytis in strawberry

Optimum conditions for Botrytis

• Humid and cool.

• Infections generally commence on the flower, either rotting it outright or remaining dormant until fruit sugars and conditions are favorable.

Cultural management of Botrytis

• Plant hygiene.

• Nutrient management?

• Management of plant size?

Novel Fungicide Screens for Botrytis2008-2010

• Numbered compounds from Syngenta

• V10135

• S2200

• Grower standards Elevate, Switch, Pristine

Leather Rot Caused by Phytophthora spp.

Photo Courtesy Steven Koike

Photo Courtesy Steven Koike

Photo Courtesy Steven Koike

Photo Courtesy Steven Koike

Control of Leather Rot through Fungicides

• 4 treatments applied end of May through July.

• Fruit sampled after third and fourth applications.

• Treatments foliar applied:

- Revus 8 fl oz/A

- Ridomil 1 pt/A

- Quadris 15.5 fl oz/A

- Untreated control

Treatment: Untreated

Treatment: Revus

Treatment: Quadris

Treatment: Ridomil