It's time for farmers to get out and scout their fall crop fields as sugarcane aphids are moving in and sooner is better than later to start treatment a plan to halt their destruction.
New detections of sugarcane aphids have been reported this week in Kansas counties including Pratt, Kearney, Pawnee, Scott, Finney, Comanche, Reno, Barton and Saline, according to information from K-State Research and Extension services. Several fields in Finney, Ford, Meade and Pratt have reached threshold levels and have been treated.
Heavy aphid infestations can result in severe yield losses and farmers should be scouting their fields at this time.
“The problem is that the leaves are damaged and they can’t photosynthesize the way they need to when infested,” said former Pratt County agriculture agent Mark Ploger. “The secondary problem is that they leave a buildup of a sticky substance that makes it hard to harvest the crop.”
Sugarcane aphids are soft-bodied insects that suck sap from plant tissues. They have migrated from the south steadily since 2013, when they were first detected in Texas, Oklahoma, Mississippi and Louisiana.
“Two years ago we had a real bad problem with them,” Ploger said. “Last year, a lot of people got by without having to spray, but this year, the moisture and the warmer temperatures have really caused them to explode.”
Damage occurs when large numbers of aphids remove water and nutrients from leaves and stems during feeding. This can cause leaf puckering, stunting, reduced seed counts and smaller seeds.
The aphids excrete a substance called honeydew on which sooty mold can grow. This can give crop leaves a black appearance and interferes with photosynthesis. Aphids can also transmit viruses such as mosaic virus. Moisture stress during an aphid infestation can increase the risk for yield loss.
Ladybugs are a natural predator of sugarcane aphids, but Ploger said there are not enough of them to help control the problem once it is discovered.
“It is important to get out there and scout the fields as soon as possible,” he said. “Spraying is the only way to get on top of the problem.”
Routine scouting is necessary to estimate aphid populations and to determine if insecticides applications are necessary. Timing effective treatment to control sugarcane aphids in sorghum depends upon the size of the populations and the growth stage of the plants. K-State research and extension experts recommend that the economic threshold is 20% of pre-boot plants infested with established colonies (>100 aphids), or 30% of plants infested post-boot.
Andrea Burns, Ford County Extension Agent said that treatment options are either Transform (1 oz. per acre) or Sivanto (4 oz per acre). For earlier stage plants, Sivanto will provide a longer period of protection, but is about 40 percent more expensive. For plants that have headed out, Transform will be a more economic option, as a long period of residual activity will be less important, and it is also safer for the beneficial species.
For a list of products and labels, visit the myFields.info Insecticide Selector, or contact a county extension agent.