Agronomic Crop Insect Scouting

Small Grains
The hessian fly free date for New Castle County is October 3, Kent October 8, and Sussex October 10. If planting early, look for varieties resistant to hessian fly. Historically this has been around the first bout of cold weather. I suspect that these dates may need to be updated, but hessian fly populations have been very low for a number of years.

Another pest that can sometimes cause issues in small grains is the aphid complex. You can see a great UD Extension video on scouting for aphids here featuring Bill Cissel: The English grain and bird cherry oat aphids are the most common aphid species. Examine a linear row-ft in 5-10 locations in the field. One way to easily find aphids is to look through a backlit leaf, with the leaf between you and the sun. Backlit aphids will show up very easily.

In the last several years, barley yellow dwarf virus has not been very prevalent, but there are areas of the state with more of it. If your fields have a history of barley yellow dwarf virus, consider planting those fields towards the latter part of the planting window. Insecticide seed treatments can be an option, but they do not generally result in yield increases and only provide protection for 2-3 weeks after germination. Southern states use a fall threshold of 20 aphids per row foot in fields that have a history of barley yellow dwarf virus and cold weather is not in the forecast. Some northern states use a threshold of 100 aphids per row ft.

So far, we do not seem to be on a very unusually warm weather pattern. Last year, there were reports of alfalfa weevil damage in Kentucky in December. If we have mild warm, non-freezing weather into December and January (last year was 70 degrees before it snowed a foot) it may be worth a quick look at the terminals.

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