It seems as though soybean aphid populations have exploded over the long weekend. Several growers have reported borderline populations late last week have grown astronomically over the last four days.

Here is a reference on soybean aphids from Mike Gray:

http://ipm.illinois.edu/bulletin/article.php?id=1218

Growth stages of soybeans are found at the Iowa State University site at:

http://extension.agron.iastate.edu/soybean/production_growthstages.html

It seems we are just arriving at the R6 stage, or have reached it in the last week. This means data has not been consistent on benefits of control measures applied at this time. Check your fields, and make your best decision for you. Remember to keep days to harvest limitations in mind when deciding on a control program and product, since about three weeks is required between application and harvest for the shortest length products.