“a disease forecast system for timing fungicide applications to control strawberry fruit rots”...

“A disease forecast system for timing fungicide applications to control

strawberry fruit rots” 

Natalia Peres and Steve Mackenzie,UF – Gulf Coast REC

Clyde Fraisse and Willingthon PavanUF – Agriculture & Eng. Dept.

FL strawberry industry overview

FL ~ 8,500 ac 2nd biggest producer in U.S. 15% total strawberry production $300 million industry

Plant City – “Winter strawberry

capital of the world”

25

8000220

Strawberry Production Cyclein West Central Florida

Sept Oct Nov Dec Jan Feb Mar Apr

Peak bloom periods

Land prep / planting

Peak harvest periods

Major Strawberry Fruit Rot Diseases in Florida

Botrytis fruit rot or Gray Mold (caused by Botrytis cinerea)

Anthracnose fruit rot (caused by Colletotrichum acutatum)

October November December January February March

Planting 1st Bloom 1st Harvest 2nd Bloom 2nd Harvest

Spray program for control of BFR and AFR in FL

Botrytis

Protective sprays (captan)

Bloom sprays

X X X

Late season sprays

Anthracnose

Legard, D.E., MacKenzie, S.J. Mertely, J.C., Chandler, C.K., Peres, N.A. 2005. Development of a reduced use fungicide program for control of Botrytis fruit rot on annual winter strawberry. Plant Dis. 89:1353-1358

Disease management currently relies on calendar-based protective applications of fungicides

Disease management with a forecast system, application of fungicides are made only when necessary (requires a good understanding of the conditions suitable for disease development, i.e., host, pathogen, environment)

Calendar system vs. Forecast system

Disease models published by others to predict the incidence of Botrytis and anthracnose fruit rots were evaluated for their effectiveness to time fungicide applications in replicated field trials during the 3 consecutive strawberry seasons

Fungicides applied at variable intervals according to models and compared to a standard calendar program and an untreated control

Development of a forecast system

BotrytisBulger - Madden model

and Broome model

Length of most recent wetness period

Average temperature during wetness event

Bulger, M. A., Ellis, M. A. and L. V. Madden. Influence of Temperature and Wetness Duration on Infection of Strawberry Flowers by Botrytis cinerea and Disease Incidence of Fruit Originating from Infected Flowers. Phytopathology 77: 1225-1230, 1987.

Broome, J. C., English, J. T., Marois, J. J., Latorre, B. A. and Aviles, J. C. Development of an Infection Model for Botrytis Bunch Rot of Grapes Based on Wetness Duration and Temperature. Phytopathology 85: 97-102, 1995.

BotrytisXu model

Average day time relative humidity (%) (8:00 am to 7:45 pm)

Average day time temperature (8:00 am to 7:45 pm)

Average night time temperature (8:00 pm to 7:45 am)

Duration of leaf wetness (hr) previous night

X. Xu, D.C. Harris, A.M. Berrie. Modeling infection of strawberry flowers by Botrytis cinerea using field data. Phytopathology, 90:13671373, 2000.

Botrytis - Treatments evaluated

Treatment Fungicide spray

1. Xu model DI=0.5

2. Xu model DI=0.8

3. Broome DI=0.5

4. Broome DI=1.4

5. Bulger-Madden DI=0.5

6. Bulger-Madden DI=0.7

7. Bulger-M Captan DI=0.5;

Captevate DI=0.7

8. Calendar standard

9. Untreated control

If %INF>0.5 captan early, Captevate at bloom

If %INF>0.8 captan early, Captevate at bloom

If DI>0.5 captan early, Captevate at bloom

If DI>1.4 captan early, Captevate at bloom

If %INF>0.5 captan early, Captevate at bloom

If % INF>0.5 captan early, Captevate at

bloom

If %INF>0.5 captan,

if %INF>0.7 Captevate

captan early, Captevate at bloom

N/A

2006-07 seasonDisease incidence (%)

Treatment # SpraysSweet Charlie Festival

Calendar standard 20 3.9 d 0.4

Xu model DI=0.5 15 4.1 d 1.0

Bulger-M Captan DI=0.5; Captevate DI=0.7 12 4.1 d 1.1

Bulger-Madden DI=0.5 9 4.6 cd 1.2

Broome DI=0.5 11 5.1 cd 1.5

Xu model DI=0.8 12 6.2 bcd 1.1

Bulger-Madden DI=0.7 8 7.7 bc 1.6

Broome DI=1.4 5 9.1 ab 3.5

Untreated control 0 12.7 a 3.3

2007-08 seasonDisease incidence (%)

Treatment # SpraysSweet Charlie Festival

Xu model DI=0.5 14 0.9 a 0.4

Bulger-Madden DI=0.5 8 1.7 ab 0.4

Calendar standard 16 1.8 ab 0.3

Broome DI=0.5 11 1.9 ab 0.4

Bulger-Madden DI=0.7 4 2.4 bc 0.3

Xu model DI=0.8 12 2.6 bc 0.6

Bulger-M Captan DI=0.5;

Captevate DI=0.710 3.2 bc 0.2

Broome DI=1.4 4 3.8 c 0.6

Untreated control 0 3.9 c 0.8

Disease incidence (%)

Treatment # SpraysSweet Charlie Festival

Bulger-Madden DI=0.5 3 0.6 0.3

Calendar standard 17 0.6 0.2

Combined anthracnose and Botrytis fruit rot INF

6 0.8 0.4

Forecasted 3 0.8 0.3

Bulger-M Captan DI=0.5;

Captevate DI=0.74 0.9 0.4

Untreated control 0 1.3 0.5

2008-09 season

Anthracnose Wilson-Madden infection curves

00.10.20.30.40.50.60.70.80.9

1

0 6 12 18 24 30 36 42 48

Leaf Wetness (hr)

Dis

ease

In

cid

ence 6 C

10 C

15 C

20 C

25 C

30 C

Wilson, L. L., Madden, L. V., and Ellis, M. A. 1990. Influence of temperature and wetness duration on infection of immature and mature strawberry fruit by Colletotrichum acutatum. Phytopathology 80:111-116.

Infection curve for mature berries (cv. Midway)

42F

50F

59F

68F

77F

86F

Anthracnose - Treatments evaluated

Treatment Symptoms required Fungicide spray

1. Calendar captan only

No captan weekly

2. Calendar captan or pyraclostrobin

No captan weekly early season, pyraclostrobin late season

3. Pre-symptom W-M captan only

No If INF > 0.15 - captan

4. Pre-symptom W-M captan or pyraclostrobin

No If INF > 0.15 - captan, If INF > 0.5 - pyraclostrobin

5. Post-symptom W-M captan only

Yes If INF > 0.15 - captan

6. Post-symptom W-M captan or pyraclostrobin

YesIf INF > 0.15 - captan,

If INF > 0.5 or 1st INF >0.15 -pyraclostrobin

7. Untreated control N/A N/A

2006-07 seasonDisease incidence (%)

Treatment# Sprays

(captan; Cabrio) Camarosa Festival

Pre-symptom W-M captan or pyraclostrobin

10(6;4) 2.1 a 0.4 ab

Calendar captan or pyraclostrobin

16(12;4) 3.1 ab 0.4 ab

Calendar captan only

16(16;0) 4.0 ab 0.1 a

Post-symptom W-M captan or pyraclostrobin

6(4;2) 4.8 ab 1.2 bc

Pre-symptom W-M captan only

9(9;0) 5.5 bc 0.5 ab

Post-symptom W-M captan only

5(5;0) 9.4 cd 0.9 bc

Untreated control 0 14.3 d 2.0 c

2007-08 season# Sprays Disease incidence (%)

Treatment(captan; Cabrio)

Camarosa Festival

Calendar captan or pyraclostrobin

16(12;4)

15.5 a 5.2 a

Pre-symptom W-M captan or pyraclostrobin

11(9;2)

17.6 ab 6.3 ab

Calendar captan only

16(16;0)

20.2 abc 5.9 a

Post-symptom W-M captan or pyraclostrobin

8(6;2)

24.7 bc 7.9 ab

Pre-symptom W-M captan only

11(11;0)

27.6 c 9.8 bc

Post-symptom W-M captan only

9(9;0)

38.4 d 13.4 c

High threshold post-symptoms captan or pyraclostrobin

1 (0;1)

51.9 e 28.4 d

Untreated control 0 58.5 e 35 e

2008-09 seasonDisease incidence (%)

Treatment # Sprays Camarosa Festival

Calendar captan or pyraclostrobin 17 0.8 a 0.2

Calendar captan only 17 1.1 a 0.2

Pre-symptom W-M captan or pyraclostrobin 5 1.5 a 0.3

Combined anthracnose and Botrytis fruit rot INF 5 1.8 a 0.8

Post-symptom W-M captan or pyraclostrobin 5 2.0 a 0.4

Untreated control 0 8.3 b 0.4

Treatments selected to develop the disease forecast system

Botrytis: Bulger-Madden %INF>0.5

Anthracnose: Wilson-Madden INF>0.15; INF>0.5

(pre-symptom)

Length of most recent wetness period

Average temperature during wetness event

Development of the disease forecasting tool in AgroClimate

http://agroclimate.org/tools/strawberry/

AgroClimate.org

Peres, N.A., and Fraisse, C.W. Development of a disease forecasting system for strawberries as a tool on AgClimate. (USDA/RMA)

Strawberry Disease System

Current risk level

Disease simulation

Weather data

Spray recommendation

Spray recommendation

Email and SMS alerts

2009-10 Grower trials

2 treatments: Grower standard and model-timed applications

3 farms – 5 to 13 acres

Disease incidence – 60 plants per treatment

~20 growers signed up to receive disease risk alerts

Treatment Cultivar # Sprays BFR (%) AFR (%)

Farm 1

Model Festival 4 21.3 2.8

Grower Festival 14 30.4 0.7

Farm 2

Model Alafia 6 10.2 1.0

Grower Alafia 13 9.9 2.4

Model Sanibel 6 12.4 0.0

Grower Sanibel 13 13.8 6.0

Farm 3

Model Treasure (1) 5 42.1 5.7

Grower Treasure (1) 14 41.6 0.5

Model Treasure (2) 5 37.4 14.3

Grower Treasure (2) 14 32.0 0.9

Model Treasure (3) 5 19.2 60.4

Grower Treasure (3) 14 23.2 23.8

2009-10 Grower trials

Future plans

USDA-NIFA-SCRI project funded to:Validate and expand the forecast system to North

Carolina, South Carolina, Ohio and Iowa

Evaluate the use of models to estimate leaf wetness duration

Determine baseline sensitivities of B. cinerea and C. acutatum and develop a resistance monitoring system