2018 Strawberry Disease Update - VBgov.com...2018 Strawberry Disease Update Chuck Johnson Virginia...

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


Fungicide Resistance between seasons in FL


All Gray Mold isn’t the same

2017 – Rupp et al


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


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

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

http://www.peachdoc.com/

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


When both diseases are present but no fungicide resistance:


BFR AFR 1 2 3 4 5

None None Captan +

Elevate

Pristine,

Merivon,

Luna

Sensation

Switch Captan +

Polyoxin-

D

Pristine,

Merivon,

Luna

Sensation



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


Abound or Azaka

Captan+

PhD, OSO

12+9+

7+17

None Thiram +

Cabrio, etc.


Abound or Azaka

Captan+

PhD, OSO



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


or Tavano

Captan+

PhD, OSO

12+9+17 None Thiram +

Cabrio, etc


Abound or Azaka

Captan+

PhD, OSO

12+9+7 None Captan +

Elevate


Abound or Azaka

Captan+

PhD, OSO

12+9+

7+17

None Thiram +

Cabrio, etc.


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.



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


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


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)


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


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

• With Straight Rows


• 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



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!

2018 Strawberry Disease Update - VBgov.com...2018 Strawberry Disease Update Chuck Johnson Virginia...

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