Expecting the problem to get worse before it gets better, Texas AgriLife entomologist Dr. Mike Brewer delivered the latest news about the growing sugarcane aphid threat to Coastal Bend grain sorghum producers who gathered in a meeting last week in Corpus Christi, warning them to gear up for a fight with the pest as the current outbreak intensifies.

"Sorghum is an excellent host to this new sugarcane aphid. It reproduces like crazy in sorghum," Brewer told a packed auditorium at the Texas A&M Research and Extension Center. "If it didn't reproduce as much as it did, the plant could tolerate the aphid well."

The presentation, one of many being staged across the Coastal Bend and as far south as the Rio Grande Valley, is in response to the threat to sorghum fields across large areas of coastal Texas posed by the sugarcane aphid.

Less common aphid

Entomologists say the smaller aphid, while sporting a yellow tint as it matures, is not to be confused with the larger and more common yellow sugarcane aphid that injects a toxin into host plants.

Until confirmation last week, entomologists were not certain how to classify the 'new' aphid. But a definitive identification was reached last week by Dr. Scott Armstrong, USDA-ARS Entomologist from Stillwater, Okla.

Armstrong acquired sugarcane aphid DNA from Texas, Florida and African aphids for comparison before making a positive identification. His research confirms that the sugarcane aphid currently posing a threat to Texas sorghum is the same Melanaphis sacchari aphid found in South Africa and in Florida.

"The good news is that we are guessing the threshold for this aphid in Texas sorghum is as high as 200 aphids per leaf, or about 30 percent of the leaves on the plant," Brewer added.

 

The aphid enters the plant to feed on the lower leaves until population numbers force it to climb higher in the maturing plant, eventually into the sorghum head once developed.

Brewer said the primary reason this aphid poses a serious threat to sorghum is because of how rapidly population numbers can grow, almost 'overnight', and because of a prolific amount of honey dew the aphid produces on the plant, which leads to a "sooty mold" that  turns the leaves black, causing irreparable damage.