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7. Know the Economic Thresholds for Insects

economic threshold and injury levels

Economic thresholds may not be perfect, but they can help you avoid an expensive mistake—paying more money to control an insect problem than you would have lost if you did nothing. By helping you avoid unnecessary pesticide applications, economic thresholds keep money in your wallet and minimize environmental problems.

An economic threshold, or action threshold, is the point at which you need to take action to prevent a pest population from reaching an economically damaging level. The economic threshold is always slightly less than the economic injury level, or EIL—the level at which a pest population is sufficiently high to cause significant crop damage.

farmer checkin bean field Keep in mind that economic thresholds are flexible guides, not recommendations carved in stone. One problem is that most currently used thresholds are rather simplistic. They do not take into consideration what happens when there are multiple pests in a field, and they can be affected by numerous economic and environmental factors.
corn borer pupa Some of the newer economic thresholds available today take these factors into consideration. For instance, many states have developed excellent, comprehensive worksheets to help you determine economic thresholds for European corn borers.
fall armyworm If a comprehensive threshold hasn't been developed yet for a particular pest, don't be discouraged from using the more limited, but available, threshold. Less comprehensive thresholds still serve as helpful guides.

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