Midwest Vegetable Guide - 2022 - 69

Insect Management Strategies
Insect Management
Strategies
Reviewed by Laura Ingwell - September 2021
Effective insect, mite, and slug management relies on
applying IPM strategies which include the following tools:
1. Preventive practices.
2. Properly identifying key pest insects, mites, slugs, and
beneficial organisms.
3. Monitoring and early detection of insect, mite, and slug
populations.
4. Determining the pest's economic loss potential
5. Selecting the proper pest control option.
6. Evaluating the effectiveness of employed control
options.
Preventive Insect Management
Practices
There are a number of practices that can reduce insect
numbers before you actually see the insects in the crop.
Often, decisions about these practices must be made based on
past experience with the pest.
Many of these practices are good management practices for
weeds and diseases as well, so they can easily be
incorporated into production practices that yield multiple
benefits.
Resistant Varieties: There are not many vegetable varieties
that have been bred exclusively for insect resistance.
However, there are many varieties that target resistance to
insect-vectored plan pathogens. This information is often
printed in seed catalogs or available directly from seed
suppliers. Varieties that are resistant to pathogens may still
sustain direct damage from the pest; ask your seed provider.
The information on crop resistance to insects, mites, and
slugs directly is harder to find. Some varieties of cabbage are
resistant to onion thrips. Selection of sweet corn varieties that
have husks that completely cover the ear tip and fit tightly
around the ear can reduce the amount of corn earworm
damage. Short season varieties of potatoes should be grown
when possible to give Colorado potato beetles less time to
feed and reproduce. This is not resistance, but it is a method
that growers can use to reduce insect damage by varietal
selection.
Crop Rotation: Rotating crops can reduce the severity of a
number of pest problems. Rotating potato fields can greatly
increase the amount of time it takes Colorado potato beetles
to colonize a field, thereby reducing the time the beetles have
to damage the crop. Rotating cucurbit crops can be equally
effective for cucumber beetle management. Don't plant crops
that are susceptible to wireworm or white grub damage in
fields that were previously in sod or heavily infested with
grassy weeds. In addition, it is a good idea not to plant
cabbage or onions next to small grain fields, because onion
thrips build up to very high levels in small grains and may
move into cabbage or onions when the small grains dry down
or are harvested. The effectiveness of rotation for pest
management relies on the host range of the pest (what crops
can/does it feed on) and its dispersal capabilities (how far will
it have to go to find a suitable host).
Crop Refuse and Volunteer Destruction: Destroying the
plant residue after harvest can reduce the damage experienced
the next year from a number of insects. Destroying squash
and pumpkin vines after completion of harvest can greatly
reduce the overwintering population of squash bugs and
squash vine borers. Early vine killing in potatoes will reduce
the potato beetle populations for the following year.
Volunteers that resprout from last year's crop can serve has a
harborage and a source population for insect pests on field
edges or as weeds in another crop, and should be destroyed.
Tillage: Fields that receive reduced amounts of tillage or
have some sort of grass windbreaks are often more
susceptible to damage from insects such as cutworms and
armyworms. These cultural practices may have other
advantages that outweigh the potential insect problems, but
growers should be aware of the potential for increased insect
activity. Tillage can also be effective to directly damage
insects that reside in the soil over winter or between crops.
Time of Planting or Treatment: Many pest insects go
through life according to heat units, and are subject to
weather, just like plants. Growing Degree Day (GDD) models
and weather forecasting tools have been developed for
several pests that detail when they are likely to be at a stage
that is damaging, or blow in from another area, or when they
are at a life stage that is easy to control or avoid. Because
insects tend to become active at specific times each year,
varying the time of planting can sometimes help prevent
serious insect problems.
Corn earworms and fall armyworms are usually a much more
serious problem on late-planted sweet corn. If the option is
available, planting sweet corn so that it has no green silks
before large numbers of earworm moths are flying can reduce
earworm problems. Root maggots are usually more serious
during cool, wet weather. Waiting until soil temperatures are
adequate for rapid plant growth will help reduce maggot
problems. Here are some resources for tracking weather and
predictive models related to insect pests:
* enviroweather.msu.edu
* newa.cornell.edu
* insectforecast.com
Midwest Veg Guide 2022
69
https://michiganstate-my.sharepoint.com/personal/phill406_msu_edu/Documents/Projects/Veg%20Guide/2022/enviroweather.msu.edu https://michiganstate-my.sharepoint.com/personal/phill406_msu_edu/Documents/Projects/Veg%20Guide/2022/newa.cornell.edu https://michiganstate-my.sharepoint.com/personal/phill406_msu_edu/Documents/Projects/Veg%20Guide/2022/insectforecast.com
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