The sugarcane aphid movement in Kansas has slowed down during the week of Sept. 21-25 with the sorghum crop maturing and drying down. South central Kansas seemed to be the “hot zone” this year, but many counties farther north and west had populations of these aphids as well. Some chemical reps have suggested spraying sorghum fields as soon as sugarcane aphid populations of any size are found.
However, finding a few sugarcane aphids does not necessarily warrant immediate treatment. Using our new thresholds (http://myfields.info/sites/default/files/page/ScoutCard%20KSU%20reduced%20v3.pdf), many farmers outside of the “hot zone” in Kansas did not have to spray their sorghum fields for sugarcane aphids.
The sugarcane aphid overwinters in southern Texas and is passively swept northward during the warmer months. Next season it will be important to monitor the progression of the sugarcane aphid northward from Texas and Oklahoma, and observe thresholds before treating.
This is especially important because populations of sugarcane aphid can be swept into the same fields multiple times depending on the weather, and the chemical options for treating the sugarcane aphid will be even more limited next year. A federal judge recently ruled against the use of sulfoxaflor, the active ingredient in one of our best tools against sugarcane aphid, Transform insecticide. Our SCA Task Force is monitoring the situation and waiting to hear the final ruling from the EPA. We will keep you posted on this issue.
The map above illustrates the states, colored in green, where sugarcane aphids were found in sorghum as of Sept. 18th this year. Several new state records have been recorded this year, including Virginia, Tennessee, New Mexico, Colorado, and Illinois.
For more scouting and threshold information visit: http://myfields.info/sites/default/files/page/ScoutCard%20KSU%20reduced%20v3.pdf
Sarah Zukoff, Entomologist, Southwest Research-Extension Center, Garden City