Published on: 18:06PM Jul 22, 2010
Question: A week ago (July 15) I hadn’t seen any soybean aphids. This past Monday, it was like they had exploded in one of my fields, so now I’m starting to check my other soybean fields. It’s slow going, help!
Answer: Sounds like you’re out scouting fields, which is the best thing you can do to stay on top of soybean aphid pressure between now and mid-August. The economic threshold for aphids is 250 aphids per plant. We use this threshold up until the later reproductive stages, around R4. Some research we’ve seen indicates there could be an economic benefit using this threshold through R5. You can use a simple speed counting process to determine whether you’ve reached threshold levels—it doesn’t have to take a ton of time and is certainly well worth your effort. The protocol for this process was developed by researchers at the University of Minnesota. For more information on the procedure, go to:
This blog is provided as an interactive way for you to have your questions answered by our Farm Journal Agronomists. E-mail your nitrogen, soil fertility, soil density, planter set up, scouting, and other questions to TestPlots@FarmJournal.com.
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