WACO – Blackland producers should be mindful of the sugarcane aphid, which infested grain and forage sorghum crops in parts of Texas in 2014 and can pose another threat with the upcoming crop season, said Dr. Allen Knutson, Texas A&M AgriLife Extension Service entomologist, Dallas.
Knutson gave an update on the sugarcane aphid at the Blackland Income Growth Conference in Waco recently.
The sugarcane aphid was first reported in the U.S. in Florida in 1977 on sugarcane. According to Knutson, the insect was first found feeding on sorghum in the Beaumont area in 2013, and this new sorghum-feeding biotype soon spread to the Rio Grande Valley and northward through Texas.
“Sugarcane aphids feed on plant sap, causing sorghum leaves to turn purple and yellow and reducing yield,” Knutson said. “This aphid also produces great quantities of sticky honeydew which collects on leaves and stalks. At harvest, these sticky plants clog up combines and reduce harvest efficiency.”
Sugarcane aphids are gray to tan or light yellow and feed on the underside of sorghum leaves. Greenbugs also feed on the underside of sorghum leaves, but are light green with a dark green stripe down the back. Also, Knutson said, the new aphid should not be confused with the corn leaf aphid, which is a dark green aphid found in the whorl of the sorghum plant.
Sugarcane aphids are not expected to survive the winter in north Texas, where sorghum and Johnsongrass are killed by freezing, Knutson said, but they do survive in south Texas, where volunteer sorghum and Johnsongrass can remain green during the winter. In the spring, winged sugarcane aphids are carried by the wind into north and West Texas. All sugarcane aphids are females and have a high reproductive rate.
“That’s why it’s important for farmers to scout fields and identify the sugarcane aphid infestations as soon as possible,” Knutson said. “Infestations can increase very rapidly, so frequent field inspection is critical. An infestation of 50 aphids per leaf can increase to 500 aphids per leaf in two weeks, given favorable conditions.”
Knutson said research studies found that an insecticide applied when there is an average of 50-125 aphids per leaf is most effective in preventing yield loss in grain sorghum.
The insecticide Transform was labeled for sugarcane aphid control in grain and forage sorghum in 2014, and the Texas Department of Agriculture has again requested a Section 18 for Transform in 2015. Also, the insecticide Sivanto was recently registered for control of sugarcane aphid in sorghum.
“Screening trials have identified several breeding lines of sorghum that have good resistance to sugarcane aphid.” he said. “With time, hybrid sorghums with tolerance to sugarcane aphid should be on the market and will be very helpful in managing this new pest.”
In the meantime, Knutson said, grain and forage sorghum fields should be scouted once a week for sugarcane aphids.
“Once this pest is present in a field, infestations should be monitored twice a week and an insecticide treatment should be applied if infestations average 50-125 aphids per leaf,” he said. “A second application may be needed if infestations increase again. Although the insecticide cost is an additional expense, sugarcane aphid can be managed to minimize yield loss.”