COLUMBIA, Mo. -- Look before spraying. That is a basic principle of
Integrated Pest Management (IPM) advocated by extension specialists at the
University of Missouri-Columbia.
A new 24-page manual, "Introduction to Crop Scouting," expands on
that idea. It is available from Missouri Outreach and Extension Centers.
"A regular and systematic field-sampling program -- crop scouting --
gives field-specific information on pest pressure and crop injury," said
Fred Fishel, MU Extension IPM coordinator. "This information is essential to
the appropriate selection and application of pest management procedures."
The new manual is one in a series by specialists in the MU Plant
The manual explains the concept of "economic injury level (EIL)."
The EIL is the pest density or level of crop injury that will result in
yield loss equal to the cost of managing the pest, Fishel said. "Simply put,
it's the break-even point."
That point changes with the increase in pest damage, the cost of
control, and the value of the crop to be saved. The predicted effectiveness
of the control also comes into the equation.
"Producers are less inclined to spend more money as commodity prices
drop," Fishel said. "Likewise, high priced controls would take threat of a
greater loss, before being applied."
The economic threshold (ET) is the pest density or level of injury
at which controls should be applied to prevent an increased pest population
from reaching the economic injury level.
Fishel said that considerable research is required to establish
those economic thresholds. "So, ETs are not available for all crop pests."
Generally, ETs are more often available for insect pests than for
diseases or weeds.
A regular crop-scouting program provides an early-warning system.
Good crop scouts are attentive to many details, Fishel said. "They
should observe -- and record -- environmental conditions including the
weather, beneficial insects, pest insects, diseases, weeds, crop growth
stages, and general health of the crop."
Scouting reports help develop a field history useful in determining
a particular crop damage.
"Corn plants lodged or growing in gooseneck shape can result from
corn rootworm pruning, application of growth regulator herbicide, or shallow
rooting in wet soil. A field history can help pinpoint which cause," he
Those histories should not be in memory only, Fishel said.
Crop scouts rely not only on an insect sweep net, but also various
kinds of traps that attract pests.
"A complete and legible scouting report is the essential 'road map'
guiding pest management decisions," Fishel said. The reports can result in
general field applications, or site-specific controls.
The reports can be used for applying rescue treatments and guide
pest management in the next growing season. Overall, scouting can reduce the
amount of pesticides applied.
Increasingly, crop scouting is done not only by the producer, but
also by hired professional scouts, trained in identifying many insects,
diseases and weeds.
Other manuals in the series include soybean diseases, corn diseases,
and weed science. The manuals can be obtained from local extension centers
The manual, IMP1006, is also available postage paid for $4.50, plus
Missouri sales tax, from MU Extension Publications, 2800 Maguire Blvd.,
Columbia, MO 65211. Orders can be placed with credit card at (573) 882-7216
or toll-free in Missouri at 1-800-292-0969.