Robert Koch, Extension Entomologist
We have observed soybean aphids colonizing soybean fields over the last couple weeks. The infestation levels have been very low in all fields we have seen, which is typical for this time of year. So, please do not rush out to spray your fields after reading this. Instead, the next couple weeks will be a good time to begin your soybean aphid scouting program.
In the early season, prioritize your scouting efforts to smaller fields with wooded borders, especially those in areas with lots of buckthorn (the plant on which soybean aphids spend the winter), and early-planted fields. While scouting, keep an eye out for lady beetles and ants on soybean plants, because these are early indicators of the presence of soybean aphids. Infested fields should be scouted on a regular basis. To determine when to spray a field with insecticide for soybean aphid, use the economic threshold of 250 aphids per plant, with most of the plants infested, and aphid populations increasing. This economic threshold is the trigger point at which you should begin lining up an insecticide application to prevent the aphid populations from reaching economically damaging levels (i.e., the economic injury level, which is about 675 aphids per plant]).
For a refresher of aphid scouting, please review “Scouting for Soybean Aphid”.
The recent heavy rains in some areas could set back some aphid infestations, as the small soybean plants do not provide much protection to the aphids from rain and winds. The aphids can get knocked off the plants and die. In addition, the high temperatures (90+ degrees F) might have temporarily slowed down their population growth. However, do not rule out aphid concerns for the year. Please remember that aphids have incredible reproductive capacity and can recover quickly from set backs. Scouting is the best way for you to know what is going on in your fields.
We have observed soybean aphids colonizing soybean fields over the last couple weeks. The infestation levels have been very low in all fields we have seen, which is typical for this time of year. So, please do not rush out to spray your fields after reading this. Instead, the next couple weeks will be a good time to begin your soybean aphid scouting program.
In the early season, prioritize your scouting efforts to smaller fields with wooded borders, especially those in areas with lots of buckthorn (the plant on which soybean aphids spend the winter), and early-planted fields. While scouting, keep an eye out for lady beetles and ants on soybean plants, because these are early indicators of the presence of soybean aphids. Infested fields should be scouted on a regular basis. To determine when to spray a field with insecticide for soybean aphid, use the economic threshold of 250 aphids per plant, with most of the plants infested, and aphid populations increasing. This economic threshold is the trigger point at which you should begin lining up an insecticide application to prevent the aphid populations from reaching economically damaging levels (i.e., the economic injury level, which is about 675 aphids per plant]).
For a refresher of aphid scouting, please review “Scouting for Soybean Aphid”.
The recent heavy rains in some areas could set back some aphid infestations, as the small soybean plants do not provide much protection to the aphids from rain and winds. The aphids can get knocked off the plants and die. In addition, the high temperatures (90+ degrees F) might have temporarily slowed down their population growth. However, do not rule out aphid concerns for the year. Please remember that aphids have incredible reproductive capacity and can recover quickly from set backs. Scouting is the best way for you to know what is going on in your fields.
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