The sugarcane aphid, Melanaphis sacchari, is a new and potentially serious pest of grain sorghum in Texas.  It was first identified in North Texas in 2013 when it infested thousands of acres of grain sorghum. It’s back earlier this year.

The sugarcane aphid first came to my attention when growers began calling me about harvesting difficulties associated with the heavy coating of honeydew on the plants.  The honeydew, a sticky sugary substance secreted by the aphids, was gumming up the augers in the combines and grain wagons.  Upon further inspection of these plants, I found huge populations of this aphid, coating the underside of the leaves and the stalks.  I believe the aphid arrived late enough in the growing season that it did not significantly reduce yields last year.

For the latest on southwest agriculture, please check out Southwest Farm Press Daily and receive the latest news right to your inbox

It came in earlier this year and poses a significant threat to grain sorghum in North Texas.  I could find some aphids in almost every field I inspected on July 1, with damaging numbers in a few fields.  Research is currently underway to determine a damage threshold for applying an insecticide, but definitive results are not yet available.  We are using an action threshold of 30 percent to 40 percent infested plants to trigger an insecticide application. 

I would define an “infested” plant as one with at least one aphid colony (one or more adults with multiple nymphs) on at least one leaf.  Leaves from the mid an upper canopy should be inspected (10 upper leaves and 10 mid leaves per location) from 5 to 10 locations across the field.  Avoid sampling field edges as aphid populations are often higher on borders than in the middle of the field.  Where aphids are found, check fields every 3 to 4 days to determine if the population is increasing.  Sticky honeydew on the leaves is a good indicator of their presence.