2018 Strawberry Disease Update

Chuck Johnson

Virginia Tech Southern Piedmont AREC

Blackstone, VA

Image courtesy Nathan O’Berry, VCE, Isle of Wight County

What’s the problem?

Phytophthora Crown Rot

• Phytophthora cactorum

Controlling Phytophthora Crown Rot

•Ridomil Gold•Best applied thru the drip

•1 pt/treated acre (½ pt/planted acre)•Only ~½ of each crop acre actually “under plastic”

Controlling Phytophthora Crown RotField Sprays After Planting

•Phosphite (53.6%), 2½-5 pt/A, or

•Aliette WDG (80%), 2½-5 lb/A .

Anthracnose Crown Rot

• Colletotrichum spp.

Controlling Anthracnose Crown RotField Sprays After Planting

In Fall: Captan every 10-14 days in fall (2-3 sprays)

Fungicide Resistance in Strawberry Plants

• A = 2011-2012;

• B = 2013

• Resistance to multiple FRAC groups in transplants each year

• % resistance varies among nurseries & year

2017 – Oliveira et al

Gray Mold doesn’t over-summer in FL

2017 – Oliveira et al

Fungicide Resistance between seasons in FL

2017 – Oliveira et al

All Gray Mold isn’t the same

2017 – Rupp et al

All Gray Mold isn’t the same

2016 samples• B. fragariae in 2 of 5 VA fields

• Always with B. cinerea

• 20-30% where found

• Incidence = ~43% in NC & GA, 61% in SC

2017 – Dowling, Hu & Schnabel;, Clemson

All Gray Mold isn’t the same

2017 – Dowling, Hu & Schnabel;, Clemson

2016 samples• Resistance common to ≥ 1 FRAC class, up to 4

• But not to FRAC 8 (cyprodinil – Switch)

• But not to FRAC 7 (Fontelis, Kenja)

PPolyoxin-D Resistance in B. cinerea(PhD, OSO, Tavano)

2017 – Dowling et al., Clemson

Estimated Frequency of Fungicide Resistance in Botrytis & Anthracnose

FRAC BFR Botrytis Resistance AFR

Captan or Captec M4 ++ None ++

Captevate M4+17 +++ Prevalent for ‘Elevate’ ++

Thiram M3 ++ None +

Fracture M12 + No Data No Data

Topsin M 1 Not effective Widespread Not effective

Rovral 2 ++ Prevalent Not effective

Tilt and generics 3 Not Effective Not applicable +

Fontelis 7 +++ Prevalent +

Kenja 7 +++ NOT Prevalent Not effective

Scala 9 ++ Prevalent Not effective

Pristine 7+11 ++ Prevalent +++*

Merivon 7+11 +++ Prevalent +++*

Luna Sensation 7+11 +++ NOT Prevalent +++*

Cabrio 11 Not effective Widespread +++*

Abound or Azaka 11 Not effective Widespread +*

Switch 12+9 ++ NOT Prevalent ++

Elevate 17 +++ Prevalent Not effective

Ph-D, OSO 19 ++ NOT Prevalent No Data

Estimated Frequency of Fungicide Resistance in Botrytis & Anthracnose

FRAC BFR Botrytis Resistance AFR

Captan or Captec M4 ++ None ++

Captevate M4+17 +++ Prevalent for ‘Elevate’ ++

Thiram M3 ++ None +

Fracture M12 + No Data No Data

Topsin M 1 Not effective Widespread Not effective

Rovral 2 ++ Prevalent Not effective

Tilt and generics 3 Not Effective Not applicable +

Fontelis 7 +++ Prevalent +

Kenja 7 +++ NOT Prevalent Not effective

Scala 9 ++ Prevalent Not effective

Pristine 7+11 ++ Prevalent +++*

Merivon 7+11 +++ Prevalent +++*

Luna Sensation 7+11 +++ NOT Prevalent +++*

Cabrio 11 Not effective Widespread +++*

Abound or Azaka 11 Not effective Widespread +*

Switch 12+9 ++ NOT Prevalent ++

Elevate 17 +++ Prevalent Not effective

Ph-D, OSO 19 ++ NOT Prevalent No Data

Botrytis Resistance Profiles – Chesapeake-B (Chandler/Camarosa)

FRAC Group

Switch Elevate Top-MCabrio,

Abound+

Rovral,Fontelis

Isolate Control 9 12 17 1 11 2, 7

1 +++ ++/+++ -/- +++/+++ +++/+++ +++/+++ -/-

2 +++ +/+++ -/- ++/+++ +++/ +++/ -/-

3 +++ +++/+++ -/- +++/+++ +++/ +++/ -/-

4 +++ ++/+++ -/- +++/- +++/ +++/ -/-

5 +++ -/+++ -/- +++/+++ +++/ +++/ -/-

6 +++ +++/+++ -/- +++/- +++/ +++/ -/-

7 +++ +++/- -/- +++/+++ +++/ +++/ -/-

8 +++ +++/+++ -/- +++/+++ +++/ +++/ -/-

9 +++ -/- -/- +++/+++ +++/ +++/ -/-

10 +++ +++/- -/- +++/+++ +++/ +++/ -/-

Anthracnose Resistance to FRAC 11 Fungicides:Pungo-B & Chesapeake-B Locations

Sample Fruit Field identification Phenotype

1 A Chandler #5 R

1 B Chandler #5 R

1 C Chandler #5 R

1 D Chandler #5 R

1 E Chandler #5 R

1 F Chandler #5 R

2 A Camarosa VB#4 S

2 B Camarosa VB#4 R

2 C Camarosa VB#4 R

2 D Camarosa VB#4 R

2 E Camarosa VB#4 R

2 F Camarosa VB#4 R

3 A Ruby June VB#6 R

3 B Ruby June VB#6 R

3 C Ruby June VB#6 R

3 D Ruby June VB#6 R

3 E Ruby June VB#6 R

3 F Ruby June VB#6 R

4 A Chesapeake #1 Camarosa R

4 B Chesapeake #1 Camarosa R

4 C Chesapeake #1 Camarosa R

4 D Chesapeake #1 Camarosa R

4 E Chesapeake #1 Camarosa S

4 F Chesapeake #1 Camarosa S

5 A Chesapeake #3 Ruby June R

5 B Chesapeake #3 Ruby June R

5 C Chesapeake #3 Ruby June R

5 D Chesapeake #3 Ruby June R

5 E Chesapeake #3 Ruby June R

5 F Chesapeake #3 Ruby June R

5 A Chesapeake #2 Chandler R

5 B Chesapeake #2 Chandler R

6 C Chesapeake #2 Chandler R

6 D Chesapeake #2 Chandler R

6 E Chesapeake #2 Chandler R

6 F Chesapeake #2 Chandler R

Botrytis Fungicide Resistance Profiles

• Send samples to

Clemson University

(Guido Schnabel)

Instructions at:

www.peachdoc.com

2 free samples/farm

2018 Strawberry Fruit Rot Fungicide Program

2018 Strawberry Fruit Rot Fungicide Program

When Botrytis is expected but plants are verified free of anthracnose:

Resistance to: Sprays during bloom & fruit ripening

BFR AFR 1 2 3 4 5

None No AFR Switch Pristine, Merivon,

& Luna Sensation

Thiram +

Elevate

Thiram +

Polyoxin-D

Switch

2018 Strawberry Fruit Rot Fungicide Program

When both diseases are present but no fungicide resistance:

Resistance to: Sprays during bloom & fruit ripening

BFR AFR 1 2 3 4 5

None None Captan +

Elevate

Pristine,

Merivon,

Luna

Sensation

Switch Captan +

Polyoxin-

D

Pristine,

Merivon,

Luna

Sensation

2018 Strawberry Fruit Rot Fungicide Program

Resistance to: Sprays during bloom & fruit ripening

BFR AFR 1 2 3 4 5

FRAC 7 None Captan +

Elevate

Captan + Cabrio,

Abound, or Azaka

Switch Captan + Cabrio,

Abound, or Azaka

Captan+

PhD, OSO

FRAC 17 None Thiram +

Cabrio, etc

Captan Switch Pristine, Merivon,

Luna Sensation

Captan+

PhD, OSO

FRAC7+

17

None Thiram +

Cabrio, etc

Captan Cabrio

+ Scala

Captan

+ Cabrio, etc.

Captan+

PhD, OSO

FRAC12

+9

None Captan +

Elevate

Pristine, Merivon,

Luna Sensation

Thiram Captan + PhD, OSO

or Tavano

Captan+

PhD, OSO

FRAC12

+9+17

None Thiram +

Cabrio, etc

Captan Thiram Captan + Cabrio,

Abound or Azaka

Captan+

PhD, OSO

FRAC12

+9+7

None Captan +

Elevate

Captan Thiram Captan + Cabrio,

Abound or Azaka

Captan+

PhD, OSO

12+9+

7+17

None Thiram +

Cabrio, etc.

Captan Thiram Captan + Cabrio,

Abound or Azaka

Captan+

PhD, OSO

2018 Strawberry Fruit Rot Fungicide Program

Resistance to: Sprays during bloom & fruit ripening

BFR AFR 1 2 3 4 5

FRAC 7 None Captan +

Elevate

Captan + Cabrio,

Abound, or Azaka

Switch Captan + Cabrio,

Abound, or Azaka

Captan+

PhD, OSO

FRAC 17 None Thiram +

Cabrio, etc

Captan Switch Pristine, Merivon,

Luna Sensation

Captan+

PhD, OSO

FRAC7+

17

None Thiram +

Cabrio, etc

Captan Cabrio

+ Scala

Captan

+ Cabrio, etc.

Captan+

PhD, OSO

12+9 None Captan +

Elevate

Pristine, Merivon,

Luna Sensation

Thiram Captan + PhD, OSO

or Tavano

Captan+

PhD, OSO

12+9+17 None Thiram +

Cabrio, etc

Captan Thiram Captan + Cabrio,

Abound or Azaka

Captan+

PhD, OSO

12+9+7 None Captan +

Elevate

Captan Thiram Captan + Cabrio,

Abound or Azaka

Captan+

PhD, OSO

12+9+

7+17

None Thiram +

Cabrio, etc.

Captan Thiram Captan + Cabrio,

Abound or Azaka

Captan+

PhD, OSO

Use FRAC 11 fungicides only in mixtures of the lower label rate with the higher label rate of a Captan or Captec product.

2018 Strawberry Fruit Rot Fungicide Program

Resistance to: Sprays during bloom & fruit ripening

BFR AFR 1 2 3 4 5

FRAC 7 FRAC

11

Captan +

Elevate

Captan + Fontelis

or Kenja

Switch Captan + PhD, OSO

or Tavano

Captan+

Fontelis, etc

FRAC 17 FRAC

11

Captan +

Elevate

Captan Switch Captan + Elevate Captan+

PhD, OSO

FRAC7+

17

FRAC

11

Switch Captan Cabrio

+ PhD

Switch Captan

12+9 FRAC

11

Captan +

Elevate

Captan + Fontelis,

or Kanja

Thiram Captan + PhD, OSO

or Tavano

Captan

12+9+17 FRAC

11

Thiram +

Fontelis etc

Captan Captan

+ Kenja

Captan Captan+

PhD, OSO

12+9+7 FRAC

11

Captan +

Elevate

Captan Thiram Captan + Elevate Captan+

PhD, OSO

12+9+

7+17

FRAC

11

Thiram Captan Captan+

PhD, etc

Captan Captan+

PhD, OSO

For a reduced fungicide program

• Spray at FIRST bloom

• Apply subsequent sprays before predicted wet weather

• Increase time between sprays when weather is dry

• End sprays ~26-30 days before expected final harvests (early May?)

• 4 sprays may be sufficient (on average)

2016-2018: Develop and validate the mid-Atlantic weather station network for fruit rot control

2017 Strawberry Spray Evaluation Sites: Tidewater, VA

Weather Station

Pungo-B site

Pungo-C site

Chesapeake-B site

Chesapeake-P site

% Berries with Botrytis Fruit Rot

0

5

10

15

20

25

30

27-Apr 4-May 11-May 18-May 25-May 1-Jun

SAS-PungoC Grwr-PungoC SAS-ChesP Grwr-ChesP2

Pungo-C & Chesapeake-P farms

% Berries with Anthracnose Fruit Rot

0

5

10

15

20

25

30

27-Apr 4-May 11-May 18-May 25-May 1-Jun

PungoC-SAS PungoC-Cvr ChesP-SAS ChesP-Cvr

Pungo-C & Chesapeake-P farms

We learned in 2017 that we need to account for:• Frost protection/row covers• Delayed sprays due to wet fields• Fungicide resistance

COVERAGE!!

• Goal = 100%• Poor coverage = 1 of most common factors leading to poor

strawberry disease control

• All fruit rot fungicides = contact or limited translaminar

Image courtesy Andrew Landers, Cornell University

Strawberry Fruit Rot Management:Row or Directed Sprayers

Image courtesy Andrew Landers, Cornell University

Strawberry Fruit Rot Management:Boom Sprayers

• Spray beds AND row middles

• Good coverage only to upper leaves, not below

• Flat fan tips (large droplets)

• Poor spray angle to foliage

• Boom generally too far away (>4-8 inches)

Image courtesy Andrew Landers, Cornell University

Strawberry Fruit Rot Management:Boom Sprayers

• Use broadcast spray volumes and rates

• High pressures; different tips/nozzles?

• Lower booms closer to plant canopy (8 inches)

• If possible, angle tips

Strawberry Fruit Rot Management:Row or Directed Sprayers

• “Better adapted” to fields that are:• Flat

• With Straight Rows

Strawberry Fruit Rot Management:Row or Directed Sprayers

• No spray to row middles

• Closer to the crop (lower) so better spray penetration to interior of plants

• Directed nozzles also improve spray deposition

• Match spray volume to canopy size:

• 3 nozzles/row early

• 5 nozzles/row later

Image courtesy Andrew Landers, Cornell University

Strawberry Fruit Rot Management:Row or Directed Sprayers

Sprayer & Spray Volume

Number of Tips Qt/100 ft Gallons/Acre

Boom Sprayer 2 40

Hoop Sprayer – 3 3 79

Hoop Sprayer – 5 4 105

Bing search fungal spore germination on leaf, 29 February, 2016

• Key consideration = fungicide concentration

– How much product/gallon of spray

– If Broadcast basis:

• Spray volume = 100 gal/A

• Medium Captan 80W rate = 2.8 lb (45 oz)

• Low Luna Sensation rate = 6 fl oz

Bing search fungal spore germination on leaf, 29 February, 2016

• Key consideration = fungicide concentration

– If “banded” or “treated acre” basis - 30” bed, 5 ft

centers (60”):

• Spray volume = 50 gal/A

• Medium Captan 80W rate = 1.4 lb (22 oz)

• Low Luna Sensation rate = 6 fl oz

CONCENTRATION!!

• Goal = minimum concentration to kill fungal spores• Example: 1.9-3.8 lb Captan 80WDG/100 gal/acre

• Medium rate = 2.8 lb /100 gal or 1.4 lb/50 gal

• High rate = 3.8 lb/100 gal or 1.9 lb/50 gal

• Medium rate at 50 gal * 6 sprays = 137oz (8.6 lb)

• High rate at 50 gal*6 sprays = 182 oz (11.4 lb)

• High rate at 12 gal 1st spray, 25 gal at 2nd-3rd sprays, 50 gpa at 4th-6th sprays = 128.9 oz (8.1 lb)

Soilborne Strawberry Diseases

• Soil-borne pathogens: Fungi & Nematodes

–Conventional:• Pic-Clor 80 (80% chloropicrin + 20% 1,3-D (Telone)

• Pic 100 (100% chloropicrin)

• Paladin (DMDS)

• Metam products (Vapam, K-Pam, Sectagon, etc.)

–Non-Conventional:• Dominus (AITC)?

• Mustard meal (BioSense, BioFence FL)

• Ennoble (Muscador albus)?

Good Luck in 2018!