Photo courtesy of IPM Laboratories
I
ronically, one of the biggest misconceptions greenhouse growers
have with controlling pests and
diseases is actually related to the
success of their control programs,”
said Karin Tifft, an integrated pest
and disease management (IPDM)
consultant. “If growers are doing
a good job, it seems simple. But
when things go wrong, they can go
wrong in a big way.”
Tifft works primarily with greenhouse vegetable growers to develop IPDM programs. While she
doesn’t yet have any ornamental
plant growers as clients, she said
she expects setting up an effective
IPDM program for ornamentals
would be more challenging because the whole plant needs to
look good, not just the fruit. She
said that ornamental growers actually have more natural enemies
and chemical options than food
crop producers.
“Microgreens and lettuce probably come the closest to selling the
whole plant like with ornamentals,” she said. “The difference is
that microgreens and lettuce are
such short term crops that there is
not a lot of time for pest and disease pressures to build up as much.
However, this does not mean proactive treatments, as in the release
of natural enemies, are not needed.
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The greenhouse is never
usually empty when growing
lettuce and greens.”
Tifft said an IPDM program can
incorporate multiple techniques,
including cultural, chemical and
biological.
“My specialty is what I call BioIPDM, biologically-based integrated
pest and disease management,” she
said. “I focus first on using natural
enemies where I can. For the disease
aspect, I look a lot at cultural control.
This includes the ways disease can be
prevented in the first place or limiting
the spread and economic losses.”
Managing
greenhouse diseases
Tifft said managing the greenhouse
climate is the best way to manage
fungal diseases.
“Fungal diseases, in particular, usually have an outbreak due to something
going wrong with the climate,” she
said. “Fungal spores, like Botrytis, are
always present. But even though the
spores are there, there is no disease
outbreak.
“Growers have to be sure the greenhouse
environment is not conducive to the expression of the disease. It is crucial that
growers check their greenhouse environmental settings both by computer and
Ph
oto
y
by A
delyn Photograph
IPDM consultant Karin Tifft said an IPDM program can incorporate
multiple techniques, including cultural, chemical and biological.
by personal observation at various
times during the day, including early
morning and at night.”
Tifft said in the case of greenhouse tomatoes and peppers she
doesn’t usually recommend making any proactive preventive fungicide applications for Botrytis.
She will use them if Botrytis is
spreading quickly.
“Disease control with cucumbers can be more challenging,”
she said. “Growers should select
powdery-mildew-resistant varieties to avoid having to apply
fungicides too frequently. There
are other cucumber diseases that
are prevalent including Didymella bryoniae that causes gummy
stem blight and Botrytis.”
Tifft said the greenhouse vegetable growers she is working with
are currently applying chemical
controls on an as-needed basis.
She said for some of them there is
the potential to move away from
pesticides altogether.