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Soybean Aphids are Gearing Up

We are starting to see aphid numbers build at a couple of our soybean aphid monitoring sites. One in particular in Brant County has 100-150 aphids per plant. These beautiful summer days that we are finally getting are also the days that are prefect for aphids. The frequent rain events that we had been experiencing up to now made it less ideal for them as moisture helps promote the growth of entomopathogens that kill the aphids. But some areas are not getting as much rain anymore. And any new storm fronts that come our way could be carrying aphids from other regions that have been reaching threshold levels. Minnesota, North Dakota and Indiana have several fields that have reached threshold over the last few weeks. And many of the storm fronts that we have been getting have blown over those regions first before arriving here.

So, get out and scout your fields once a week for the next few weeks to make sure that your fields do not reach thresholds of "250 aphids per plant and increasing on 80% of the plants in the field." Remember pulling the trigger too early can do more harm then good so don't convince yourself to spray at 150 aphids just in case. The natural enemies that were helping you out will be killed, leaving the aphids to increase again above threshold. This threshold applies for soybeans in the R1 to R5 stages of soybeans.