Sugarcane aphids have now been confirmed in Barton County. From reports in Oklahoma, as well as some southern counties in Kansas, this insect has a very good chance of being a serious issue in Sorghum fields. The aphid has been causing serious problems in Georgia where some farmers have been seeking insecticide alternatives after two applications of Transform, the allowable limit. Right now, scouting your sorghum fields twice weekly can allow you to assess if you have the aphid, and at what levels. The sugarcane aphid reproduces very fast, so they can reach the threshold quickly. If spraying is warranted, use a spray that is gentle on beneficial insects. This will help control the aphid further. I do have a scouting card at the office that you can pick up, or I can mail it out. For any concerns, you can contact me at 620-793-1910, or by email at aboor@ksu.edu
Sugarcane aphids are small; light yellow to grey with dark cornicles (paired tailpipelike structures on the rear of the abdomen) that contrast with the remainder of the body. They are all female, and reproduce asexually. Adults give birth to live pregnant young nymphs. These young nymphs are mature and reproduce in 3 days’ time. They have the potential to kill seedlings, reduce seed numbers, but the most significant damage occurs as reduction in test weights. They also produce a copious amount of honeydew which can gum up machinery during harvest making it all but impossible to get the grain out of the field.
LSU AgCenter and Texas A&M Agrilife has set a preliminary threshold on boot/milk stage grain sorghum of 50 aphids per leaf colonizing 20 percent of plants in the field. With the aphids’ ability to reproduce so quickly, they can get past the threshold in a very short time, so scouting fields regularly is the best first line of defense. If it is determined that an insecticide is needed, Transform is the material of choice, preferably applied in a large volume of water (10-20 gal per acre). Sivanto is also approved, but it appears to require a higher rate to achieve similar results and ends up being considerably more expensive.
Headworms are also making their presence known in fields right now. If you have them in your fields as well as aphids, Transform will not control the headworms, another insecticide will be needed. The recommendation for headworms are: Chlorantraniliprole (Prevathon) 14.0 to 20.0 fl. oz. /acre, Chlorpyrifos (numerous products) Check label, but generally 1 to 2 pints/acre, Flubendiamide (Belt) 2.0 to 4.0 fl. oz./acre, Methomyl (Lannate) 0.45 lb. a.i./acre, and Spinosad (Tracer) 0.047 to 0.094 lb. a.i./acre (1.5 to 3 fl. oz.)
For more information about the sugarcane aphid and headworms, or if you think you have them in your field, contact your local Extension office.
Alicia Boor is the Agriculture and Natural Resources agent for Barton County K-State Research and Extension. You can contact her by e-mail at aboor@ksu.edu or calling 620-793-1910