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Wasps Welcome at Sweet Corn Farm
Sweet
corn accounts for approximately one-third of the fresh market income
at Cheryl and Dave Henderson’s cash crop farm in Penn Yan, NY.
The Hendersons, who also sell vegetables for processing and field crops,
almost
eliminated sweet corn from their business mix when European corn borers began
destroying one-third to one-half of a planting. The insect is an annual pest
that needs control.
“European corn borer is a management challenge for organic growers, growers
marketing no spray sweet corn, and small-acreage growers who cannot justify
the cost of the large, specialized spray equipment needed for sweet corn,”
says Abby Seaman, an Integrated Pest Management educator with the New York
State IPM Program of Cornell University.
“We were asking ourselves what to do when Abby invited us to participate in
the project evaluating wasps as a control,” Cheryl says. “We are definitely
glad we said yes.”
With a $9,968 grant from the New York Farm Viability Institute in 2005, Seaman
worked with five growers to evaluate the use of Trichogramma ostriniae,
a tiny wasp that parasitizes the eggs of the European corn borer.
Dave Henderson adds, “For us as small acreage growers (1.5 acres of sweet
corn), the wasps are extremely cost effective, better than doing nothing and
better than using a boom sprayer. Without insecticide, some years we lost a
huge part of our crop. Even with insecticide we were still losing five to ten
percent. The first year we tried the wasps they worked much better than the
insecticide.”
Cheryl says using the wasps is “simple and safe. I do not have to put on a
spray outfit... no rubber gloves, no coveralls. They save time and equipment
cost. Our operation is not large enough to buy a high-boy sprayer, and using
the wasps eliminates the worry of getting spray on ourselves or where it might
drift.”
Seaman notes that “depending upon the strain of moths present in the area, the
European corn borer may lay eggs for part or all of the growing season. That
makes the use of Trichogramma wasps a little tricky.”
“The timing for releases is hard to predict. The moths (of the European corn
borer) don’t tell you when they’re coming and the wasp grower generally likes
two weeks notice. We watch the pheromone trap network report
(
http://nysipm.cornell.edu/scouting/scnetwork/default.asp ) for when to
expect peaks in moth populations and we watch the field to make week-to-week
decisions. This process is similar to trying to time spraying,” Cheryl says.
Once she orders the wasps (researcher-produced for the Institute-funded trial,
now commercially produced by IPM Laboratories in Locke, NY), Henderson says
she must remember to check the roadside mailbox.
“You don’t want the packet to sit too long in a hot mailbox. We get four
little envelopes (a total of 30,000 just-about-to-hatch wasps). We hang the
envelopes by rubber band on four corn stalks spaced throughout the field and
away from the edges. I put them under the leaves so the wasps are protected
when they first come out, ”she says.
First release is usually in June when the moths are flying and corn reaches
the 6-8 leaf stage. Subsequent releases coincide as moth flight demands, with
the last release about the time the corn reaches late whorl to tassel
emergence.
Dave says, “Insecticide cost us $15 per acre per spray. The wasps cost $15 for
each release plus $5 shipping. We have released the wasps at least three times
each year since 2005. Sometimes more frequently depending on the number of
corn plantings and the timing of the planting. We see the results when we
harvest.”
For More Info on the New York Farm Viability Institute-funded
Trichogramma wasps project:
• Abby Seaman, NYS IPM Program, 315-787-2422,
ajs32@cornell.edu
This article first appeared in the November 2007 issue of American
Agriculturist.