Soybean Aphids Increasing but Not So Fast

Monday and Tuesday afternoon were spent looking at soybean and corn fields along the route I have setup along County Road's B & L. Soybean aphids were an observation to be made in all soybean fields. Basically I do this not to scout a field for threshold information, but get out in the field away from the end rows and look for the presence of aphids.

The route this year has 52 soybean fields. On the 8/3 and 8/4 scouting, 26 fields had aphids and 26 did not have aphids. If you remember back to my last report on aphids on July 17th only 2 of the 52 fields had aphids in them. So aphids are now easier to find. I would not be surprised if you spent time in a field until you found aphids, that you would be able to find aphids in nearly every field.

From my stops the past couple of days though, we still are not close to threshold of 250 aphids per plant. I went to one of the fields that had aphids back on July 17th and population were just 3-4 per plant and only 30% of the plants had aphids on them which was not different than most other fields. Most fields had 3-6 plants out of 20 with aphids on them or 15-30% of the plants. Numbers of aphids per plant were less than 10. As always there was a field that did not fit the mold and had 18 out of 20 plants or 90% of the plants with aphids, but the average was just 15 per plant . This is a field I will go back to over the next couple of weeks.

From a growth stage standpoint, most soybeans are in the R3 growth stage where there is one 3/4 inch long pod at one of the 4 top nodes on the plant.