I’ve had a number of questions about including insecticide with fungicide applications.  In almost all cases, there are not significant insect infestations in the field.  It is purely a convenience application.  In fact, most reports are of light aphid and cereal leaf beetle infestations, and little or no armyworm activity.  Some have used the logic that insect populations are ahead of schedule, but so is the wheat.  At this time of year, insecticides should be applied as needed based on scouting.  Wasting just a few dollars per acre adds up, and besides, being “spray happy” is not the impression we want to give the general public.  Wheat can tolerate a fair amount of defoliation without yield loss.  The old argument that “I want to spray now because I don’t want to come back later” is pretty weak as the insecticides we use (mostly pyrethroids) will last 5-7 days or until the first good rain, whichever comes first.  There are no guarantees that you won’t have to spray later just because you already made an application.

I have had a few reports of armyworms at or near treatment level.  In these cases, there is an opportunity to take advantage of fungicide applications to control insects by adding insecticide.  Just use a little professional judgement, and don’t abuse insect thresholds just because you are making a fungicide application.  I’ve had several calls on wheat curl mite, which as the name implies, causes the leaves to curl and also transmits wheat streak mosaic virus.  These are tiny mites that can’t be seen without the aid of magnification.  There are no effective insecticides or acaricides for this pest.  The best way to prevent wheat curl mite and the virus it transmits is to eliminate grassy weeds or volunteer wheat well before planting.

The recommended treatment threshold for armyworms in wheat is 6-8 larvae per foot of row prior to and during the milk stage.  Relatively recent data from the University of Arkansas indicates that nearly complete defoliation has little affect on yield once wheat is past the milk stage.  Synthetic pyrethroids work well.

 

It is too late to worry about Hessian flies, and I’m not aware of any issues this year anyhow.  Aphids should only be treated if numbers are very high (several hundred per foot of row) and causing symptoms of injury.  Treat for cereal leaf beetles if one larva or adult is present per plant (or alternatively, 25 larvae per 100 tillers) or defoliation exceeds 20-30%.