Texas Grain Sorghum: Sugarcane Aphid Resistance Confirmed In 14 Hybrids

Photo: Justin Ballew, Clemson University

Extension Entomologist Dr. Allen Knutson has released a list of sugarcane aphid resistant sorghum hybrids. The entries are based on multiple years of replicated field trials by AgriLife personnel Robert Bowling, John Gordy, Danielle Sekula, Mike Brewer and Allen Knutson. It should be noted that none of these trials are from the High Plains.

The remainder of this article is quoted directly from Dr. Knutson’s document.

“Soon after sugarcane aphid emerged as a pest of sorghum in 2013, growers, consultants and seed company representatives observed that some hybrids were not as heavily infested with sugarcane aphids as were other hybrids.

These observations led to field research studies that confirmed that some hybrids were resistant to sugarcane aphid due to their genetic makeup.  As a result, many seed companies now market hybrids with some resistance or “tolerance” to sugarcane aphid.

Beginning in 2014, Texas A&M AgriLife Extension and Research evaluated some of these hybrids in replicated field trials. Trials were conducted in the Rio Grande Valley, Gulf Coast and north Texas and compared the number of sugarcane aphids and leaf damage to hybrids known to be susceptible to sugarcane aphid.

These trials confirmed resistance in 14 hybrids from seven different seed companies ( see Table below).  This list is not complete and these and other seed companies may have other hybrids with resistance to sugarcane aphid. Also, seed companies are releasing new hybrids with sugarcane aphid resistance each year, and growers are encouraged to visit with their seed representatives regarding current hybrids.

In these trials, sugarcane aphid populations increased more slowly, and plants exhibited less leaf damage compared to susceptible hybrids.  As a result, resistant hybrids were less likely to require an insecticide treatment for sugarcane aphid.

No Silver Bullet, Of Course

However, resistant hybrids are not immune, they must be monitored for sugarcane aphid infestations, and treatment with insecticides may still be warranted to prevent yield loss or honeydew contamination at harvest.

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The level or expression of resistance may vary by geographic region, and field trials are needed to evaluate resistance of these hybrids ( see Table) and others under growing conditions in the Texas High Plains and other production regions.

In addition to sugarcane aphid resistance, yield and other agronomic qualities must also be considered in selecting hybrids for planting. Hybrids that are high yielding and well adapted, yet susceptible to sugarcane aphid, may be more profitable, and if so, can be protected from sugarcane aphid damage by frequent scouting and a well- timed application of an insecticide if needed.

While resistant varieties can reduce the risk of sugarcane aphid, they should be part of an overall pest management plan that includes early planting, weekly field scouting, use of thresholds and efficient use of insecticides, if needed, selection of insecticides applied for midge and headworms that help preserve natural enemies of sugarcane aphid, and control of Johnsongrass, an important host of sugarcane aphid.”

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