Grain fields continue to be harvested and yields have vary as widely as the rainfall from less than 3000 lbs/A to more than 7000 lbs /A.
Most of the sorghum is at hard dough or black layer and beyond the damage window for panicle feeding stink bugs and headworms. A few young fields are still blooming and remain susceptible to sorghum midge, stink bugs and headworms.
All sorghum fields are susceptible to sugarcane aphids. Some sorghum producing areas have begun to call this the “white” sugarcane aphid to prevent confusion with the yellow sugarcane aphid.
If you read articles about white sugarcane aphids in Louisiana, Arkansas, Mississippi or other states, they are the same aphid we are dealing with.
Harvesting problems are occurring in parts of Refugio County caused by the sugarcane aphid and the honeydew it produces. The fields had sugarcane aphids on the flag leaf at the time of glyphosate applications and when the leaf died, the aphids moved to the head.
In some fields, 30-40% of sorghum heads were infested with aphids. We saw aphids move to the head in an insecticide trial near Port Lavaca, applied the same day as glyphosate was applied to the field , including the whole test area.
By 10 days after treatment, some treatments averaged 60+ aphids in the head. These were producing sufficient honeydew to make the grain and upper leaves sticky with honeydew potentially causing harvest problems. Fortunately, this infestation was only in the field margins and not throughout the field. A second trial is currently underway near Victoria to evaluate the combined and separate use of Transform Insecticide and RoundUp Powermax.
More details will be available next week as we wait to see if the surviving aphids move to the head. Honeydew from the aphids has also been observed reducing the efficacy of glyphosate applications causing some recommendations o f increased rates of application.
I have heard some recommendations of using sodium chlorate instead of glyphosate as a harvest aid. This product brings a lot of issues with regard to corrosion of equipment but may be a viable alternative if the product can be found.
