The question that is on quite a few farmers minds is do I have aphids and when do I have to or should I spray?
At this point we have found Soybean Aphids, but not at sprayable levels. There are fields close to the Mississippi and Minnesota rivers that are surrounded by woods and buckthorn that have reached sprayable levels, and we have been told that they have been sprayed.
Historically in our area we see sprayable aphid numbers the last week in July, into the first two weeks of August. In my experience I normally see aphids earlier and in higher numbers in fields that are:
- Surrounded by woods and buckthorn
- Have no seed treatment or a low quality seed treatment
- Low potassium soil tests levels
- First or last planted fields.
I differ with many Agronomist as when to spray aphids, my recommendation is if we have higher than normal temperatures and below normal moisture levels I will recommend spraying before threshold.
What I have been seeing in many soybean fields, for the last few weeks which is of concern is Septoria Brown Spot, (pictured below on the left and right)
and also scattered areas of Bacterial Blight. Both diseases attack the bottom leafs first and spread up through the canopy. We normally see these diseases later in the growing season, and because of that late date they do not normally affect yield.
Because these diseases are appearing earlier than what I believe to be normal we may need to look at applying a fungicide to stop the spread of these diseases up through the canopy.
