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Understanding Aphid Thresholds
Information from Iowa State University Extension Web site
When scouting soybeans for aphids, it’s important to understand the threshold numbers.
Currently, according to Iowa State University, threshold is 250 aphids per plant on 20 to 30 plants sampled throughout the field when aphid populations are on an active increase.
It is important to check the field regularly to determine if the populations are increasing. This threshold level provides approximately five to seven days for spraying before the aphids hit an economic injury level.
Also, keep in mind that aphid populations favor cool temperatures, plant stress (particularly drought stress) and a lack of aphid predators such as Asian lady beetles and lacewing larvae.
For more information from Iowa State University Extension, click here.
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