Rob Williams

TYLER, Texas–Researchers and Extension specialists from Texas A&M AgriLife Research and Extension and three other states recently received the Friends of IPM Pulling Together Award at the Southwestern Branch of the Entomological Society of America meeting for their actions in saving sorghum crops from the sugarcane aphid.

Because of the proactive actions of team members, grain sorghum producers were spared losses in the hundreds of millions. In Texas alone, sorghum is planted on 1.25 million acres and brings a value to the state of $160 million dollars each year.

The infestation started in summer of 2013 when Texas A&M AgriLife Research scientist Dr. Mo Way in Beaumont realized that grain sorghum producers were dealing with a new aphid species. Initially, Way and his coworkers did not know the identity of the aphid, but they knew it infested sorghum. Taxonomists determined that the aphids belonged to the genus Melanaphis, but there still was uncertainty as to the species. It has since been determined to be the sugarcane aphid, Melanaphis sacchari (Zehntner)

Entomologists and farmers soon found that the pest was no longer confined to the area near Beaumont, but was present from Northern Mexico, to Louisiana, Oklahoma and Mississippi, where farmers were also reporting an unfamiliar aphid pest that was leaving a sticky residue on their crops.

Fortunately, farmers who planted in the spring of 2013 were able to harvest before aphid populations caused too much damage, but anyone who planted a late crop that year noticed a sticky residue on the leaves and in the grain heads. When those growers tried to harvest the crop, the sticky residue clogged up combines and other equipment with yield losses of over 50 percent reported.

By the fall of 2013, research and Extension in Texas, Oklahoma and Louisiana had initiated control studies and set up a multi-state task force to begin studying the pest. Also, seedling sorghum plants were immediately infested in a study in the Lower Rio Grande Valley, where the aphids killed many of the seedlings. And the plants that survived often failed to flower or set seed.

In November the task force that was initiated in the fall started working to organize research and education efforts before the 2014 growing season started. The task force included entomologists, agronomists, plant breeders, Extension agents and communication specialists to coordinate research on the biology and origin of the pest and communicate with growers about how to identify and manage it. It also included folks from Texas Department of Agriculture for their work on labeling effective insecticides.

Research in 2013 and 2014 revealed that the aphid overwintered in Johnsongrass and volunteer sorghum plants where plants survived in S. Texas. Tests showed that early season infestations could be kept in check, for a while, by seed treatments. But seed treatments did not persist long enough to prevent damage later in the season.

Tests of foliar insecticides revealed that the insecticides labeled for sorghum were not effective against sugarcane aphid. Researchers tested new generation insecticides and found one that was effective, but it was not labeled for use on sorghum. After gathering data on losses, mechanisms for crop losses and aphid impacts on harvest, these specialists provided critically important information for the Texas Department of Agriculture, who worked with EPA to obtain a Section 18 label for the insecticide Transform. The Environmental Protection Agency approved the petition on April 14, 2014, preventing a potential loss of $165 million that year in Texas.

In 2014, researchers began testing sorghum varieties for resistance to the new sugarcane aphid. After two years of research in both the lab and the field, researchers found a few varieties that looked promising, but the resistance to the sugarcane aphid in commercial hybrids were at best moderately resistant. However, Texas A&M AgriLife Research plant breeder Gary Peterson reported that although they had seen some resistance in commercial varieties, he cautioned that more research is needed before they can comfortably recommend certain varieties to growers.

“We have some potential resistant varieties,” said Peterson. “But I want to do more testing before I make any recommendations. But so far it looks promising that we’ll have some resistant varieties that growers can use in future seasons.”

Researchers on the Task Force made extraordinary efforts to become acquainted with the new aphid. Scientists in Texas and Oklahoma studied the aphid to determine damage thresholds at various growth stages. Others searched for the origin of the pest searching for predators might work against it. A sugarcane aphid blog, http://txscan.blogspot.com/ , updates growers and consultants on the movement of the aphid as well as best practices to use for managing and controlling the aphid.

To further help growers with treatment decisions, several Texas scientists developed an economic decision aid, located at http://bit.ly/1TvTEXd . Released in January of this year, the tool includes inputs for costs of treatment, sorghum prices and potential yield loss and provides a table with recommendations about whether or not to treat based on aphid count.

In 2014, the sugarcane aphid had only been detected on the Texas High Plains in a limited number of fields late in the growing season.   These infestations did not cause significant damage that year, but in 2015 sugarcane aphids infested fields earlier from mid June through September all across the Texas High Plains. Infestations were severe and losses were estimated to be substantial.

“The treatment trigger that works best on the Texas High Plains is based on percentage of plants infested at different sorghum growth stages,” says Ed Bynum of Texas A&M AgriLife Extension. “It is a more aggressive trigger compared with thresholds used in other areas in Texas. “It seems as if timing is everything for good control,” says Bynum.

Because of the research done by the Task Force, the improved communication to growers, and the labeling efforts by research, extension and TDA, nearly all producers in Texas, as well as other states, took appropriate action and protected grain sorghum crops on millions of acres in 17 states.

Scientists have discovered that a combination of biological and chemical control is currently the best strategy for reducing aphid populations. Selective insecticides as needed and predators/parasitoids work well together as a part of an IPM program. Tolerant and resistant hybrids are expected to be the foundation of sugarcane aphid IPM systems in the future. As more effective hybrids are developed, relying on them along with natural enemies is expected to reduce grower dependency on insecticides.

“The Sugarcane Aphid Team is a great example of how problems are addressed and solved by the land grant universities and agencies. This was truly a multi-disciplinary, multi-agency, multi-state effort to address a rapidly emerging, serious agricultural problem,” Professor and Extension Specialist/IPM Coordinator Dr. Charles Allen said. “Entomologists with Texas A&M AgriLife Research and Extension first detected sugarcane aphids and immediately went to work. As the magnitude of the sugarcane aphid problem became apparent, the teamwork intensified.”

He said that the task force’s effort saved thousands of tons of grain and millions of dollars from Texas Oklahoma and Kansas east to the Carolinas. “It was a remarkable IPM effort in the Southern Region and was recognized as such as the team was honored by receiving the Southern Region IPM Center’s Friends of IPM, Pulling Together Award,” he said.  “I am very proud of Entomology’s many strong individuals and teams.”