Frank J. Louws, Plant
Pathology Extension
For
growers who adopt a conservative (low risk) fungicide program, apply weekly
sprays according to ONE of the following suggested schedules:
SCHEDULE 1: For cases when there is no risk of anthracnose and
growers need to focus on gray mold control (most fields).
Application
# 1: at 10 % bloom apply captan + Topsin-M OR Switch
Application
#2 : Elevate OR Pristine
Application
#3: same as #1 if there is a “full bloom” situation
Application
#4 and weekly: Rotate two or more of the following: captan, CaptEvate, Elevate,
Switch, Pristine
Options:
Elevate may be used in 2 consecutive sprays; captan, Pristine and Switch offer
a broader spectrum of disease control. There is no advantage to tank mix
captan, Elevate, and/or Switch and/or Pristine. CaptEvate is a premix of captan
+ Elevate. In all cases follow label directions. For a reduced fungicide
program initiate applications at 10% bloom as above but apply subsequent sprays
before predicted wet weather that favors Botrytis and end applications about 26
– 30 days before expected final harvests.
SCHEDULE 2: For cases where some insurance is desired against
anthracnose but the focus remains on gray mold control.
Application
# 1: at 10 % bloom apply captan + Topsin-M OR Switch + (Quadris OR Cabrio)
Application
#2 : Elevate + (Quadris OR Cabrio) OR Pristine
Application
#3: same as #1 if there is a “full bloom” situation
Application
#4 and weekly: Rotate two or more of the following: captan, Elevate + (Quadris
OR Cabrio) OR Pristine OR Switch + (Quadris OR Cabrio).
SCHEDULE 3: Aggressive program to manage anthracnose if disease
is known to be present.
Application
# 1: at 10 % bloom apply captan + Pristine
Application
#2 : captan + (Quadris OR Cabrio)
Application
#3: CaptEvate
Application
#4 and weekly: Rotate the following combinations: captan + (Quadris OR Cabrio),
CaptEvate, Pristine.
Elevate
and Pristine will offer good Botrytis control. Switch could also be
incorporated into schedule 3 to get better management of gray mold but there
should be continuous coverage with Captan or a strobilurin, or the combination.
GENERAL NOTES: Thiram can be
substituted for Captan. It also is a broad spectrum fungicide. Cabrio is equally
effective as Quadris. Both are strobilurins with the same mode of action.
Pristine is a premix of pyraclostrobin (Cabrio) and boscalid. The strobilurin
chemistry should never be used back-to-back more than two times and no more
than 5 times total per crop season.