PowerPoint - Florida Blueberry Growers Association

Early signs of widespread fungicide
resistance in Botrytis across blueberry
fields in central Florida
Achour Amiri, Philip F. Harmon, Natalia A. Peres
Winter BGA meeting, Plant City, FL, 02/20/14
Gray mold management in strawberry
Topsin-M
Widespread Resistance in FL Strawberry Fields
13.5
14.6
85.4
86.5
95
Topsin-M
Cabrio
Pristine
40
47.3
60
Elevate
5
100
52.7
Switch (Cyprodinil)
Sensitive
Switch (fludioxonil)
Resistant
Botrytis outbreak on strawberry in 2012
The many faces of Botrytis on blueberry
Shoot tip
Shoot blight
Total blossom damage
Sporulation on a blossom
Leaf
Green and mature fruit
Gray mold management in blueberry
Trade name
Active ingredient
Efficacy*
Resistance Risk
Cabrio
Pyraclostrobin
+ (curative ?)
Pristine
Pyraclostrobin + Boscalid ++
++++
Fontelis**
Penthiopyrad
+++
+++
Elevate/Captevate Fenhexamid
+++
+++
Switch
Fludioxonil+cyprodinil
++++
+/+++
Captan/Captec
Captan
++
(Protectant)
++++
?
* Efficacy will depend on frequency and distribution of resistant population
** Labeled for lowbush blueberry
Survey of fungicide sensitivity in Botrytis in Central- FL
 10 locations surveyed in 2013 (March-May)
 2 in Polk County
 3 in Citrus County
 5 in Hillsborough County
 Total number of isolates: 192
 Sensitivity to 9 fungicides from different chemical
groups
Fungicide sensitivity in Botrytis in Central- FL
Switch
* The other active ingredient of Pristine
Is population shift between crops a potential source of resistance in blueberry?
?
Labeled in strawberry
not in blueberry
* Labeled for lowbush blueberry
** Not registered yet
New, potentially
effective
From the same chemical group
Some variability but resistance is spread across locations
Resistance frequency (%)
Location
1
2
3
4
5
6
7
8
9
10
a
County
Polk
Polk
Citrus
Citrus
Citrus
Hillsborough
Hillsborough
Hillsborough
Hillsborough
Hillsborough
a
n
15
10
15
20
40
20
10
15
19
28
Cabrio
100.0
90.0
100.0
85.0
85.0
100.0
90.0
86.7
64.4
100.0
Pristine
73.3
10.0
80.0
30.0
52.5
65.0
60.0
33.3
42.1
78.6
Number of isolates from each field
* Both active ingredients of Switch
Elevate
40.0
40.0
20.0
45.0
52.5
85.0
10.0
20.0
21.1
71.4
Cyprodinil*
40.0
40.0
60.0
30.0
42.5
60.0
20.0
60.0
31.6
60.7
Fludioxonil*
0.0
0.0
0.0
0.0
0.0
0.0
0.0
13.3
0.0
0.0
Management at risk because of multiple resistance
Phenotype Resistant to
MFR2
MFR3
MFR4
MFR5
MFR6
MFR7
2 fungicides
3
“
4
“
5
“
6
“
7
“
MFR = The same isolate may
be resistant to 2, 3, 4 or more
fungicides, simultaneously.
Best management practices
Spray when the plant is most susceptible:
Flowering
and
When weather conditions are conducive:
Temperature (~68°F) and wetness (10 to 14h)
Is reducing number of sprays the solution?
Locations of weather stations
Citrus County: Floral City
Polk County: Lake Alfred
Hillsborough County:
Dover
Plant City
Balm
Reducing sprays doesn’t seem to affect control efficacy
2011-2012 Strawberry season
11
21
8
16
15
10
17* 9
* Number of fungicide applications/season
Calendar = Weekly application
Alert = Spray only when conditions are conducive to Botrytis
Spray at appropriate timing and growth stage
 Low Botrytis Risk: spray Captan
 Moderate Botrytis risk: spray Elevate, Pristine,
Fontelis (lowbush)
 High Botrytis risk: spray Switch
Preferably within the 24 hours following the alert
Monitoring weather conditions, sign up, alerts:
http://www.agroclimate.org/tools/strawberry/
Additional management recommendations
https://edis.ifas.ufl.edu/hs380
Perspective
 Conduct additional resistance monitorings
across the State: Please contact us
 Develop efficient rotation programs
 Investigate the impact of different sources
of botrytis inoculum
Acknowledgements
Contact Information:
Dr. Achour Amiri
Gulf Coast Research and Education Center
14625 CR 672
Wimauma, FL, 33598
Phone: 813-633-4153
Email: [email protected]
Dr. Harmon and Dr. Peres
Participating growers
 Mr. Gary K. England
Strawberry pathology lab team