By: Adam Russell

Grain sorghum producers are reporting sugarcane aphids in the High Plains, but the pest has made little impact on the Texas crop during 2020, according to Texas A&M AgriLife Extension Service experts.

But forage sorghum, an increasingly popular silage option, has experienced more significant losses, as producers and Texas A&M AgriLife scientists and specialists search for effective and efficient treatment methods. Those fields bound for forage production were not hard hit so far this year.

Pat Porter, Ph.D., AgriLife Extension entomologist, Lubbock, said sugarcane aphids have not been “as big a deal as they were years ago” due to creation of resistant hybrid sorghum varieties and vigilant monitoring and spray applications keeping their numbers in check as they migrate.

Sugarcane aphids on sorghum leaf
Sugarcane aphid nymphs and an adult on a grain sorghum leaf. (Texas A&M AgriLife Extension Service photo by Pat Porter)

Sugarcane aphids devastated sorghum fields after their 2013 emergence in fields around Beaumont. They made their way to the Texas Plains by 2015, and the results were catastrophic for sorghum producers.

Producers in the Rio Grande Valley alone lost $31 million to the pest in 2015, according to an AgriLife Extension study that also showed producers who utilized recommended scouting and spraying regimens once the pest neared thresholds avoided $35 million in potential losses.

Since then, sugarcane aphids effect on Texas’ sorghum production has waned, and Porter said this season has shown numbers continue to decline.

“There’s so many fewer aphids coming up from South Texas,” he said. “The resistant hybrids are the No. 1 factor, and then you have producers in South and Central Texas who are on top of their numbers and really decreasing the migratory populations.”

Porter said some producers along the Gulf Coast sprayed their fields, but he suspects sugarcane aphids may be manageable in the High Plains without applications if beneficial insect populations are well-established.

Forage sorghum

Forage sorghum, however, continues to be impacted by sugarcane aphids because there are very few aphid-tolerant forage sorghum hybrids. It is also planted more densely and grows taller than grain fields. Those factors make spray applications less effective and forage fields more susceptible to significant infestations.

Jourdan Bell, Ph. D., AgriLife Extension agronomist, Amarillo, said forage sorghum has become an increasingly important silage option for beef cattle and dairy producers in the region. It’s a drought-tolerant alternative to corn silage and can withstand intermittent periods of in-season drought stress without losing quality as quickly as corn.

Bell said Texas A&M AgriLife Research efforts are showing that sugarcane aphid effects on forage yields and quality can be mitigated with actions that reduce their impact on grain fields – timely identification and management.

Untreated test plots experienced 33%-44% yield losses and reduction in quality as a forage, she said. Data showed relative feed quality was reduced by as much as 50% under heavy sugarcane aphid infestations.

“With the arrival of sugarcane aphids on the Texas High Plains, we have seen many forage sorghum fields lost to sugarcane aphid feeding as well as yield and quality reductions,” she said. “It is important that producers and consultants are scouting their forage sorghum fields and applying timely insecticide application to maintain yield and quality.”