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AgriLife officials were astounded at the rapid jump in aphid numbers.
The “white” sugarcane aphid is translucent at early stages with a pale yellow tint and becomes a little darker yellow as they mature. But Sekula-Ortiz says a distinct difference is obvious once you see the two aphid varieties side-by-side. The yellow sugarcane aphid is “neon” yellow and generally larger and when scouting fields growers may find a few of the yellow aphids and hundreds of the new white aphid variety.
"These are the ones we are concerned about," she said.
Over a two week period of scouting for the new aphids and committing those results on a graph, AgriLife officials were astounded at the rapid jump in aphid numbers. Eleven large commercial sorghum fields were used to chart the outbreak and Sekula-Ortiz said in spite of scouting the test fields regularly, they felt like they were caught by surprise when population numbers suddenly skyrocketed.
"I think it was a number of factors that contributed to this population explosion—warmer weather, maturing plant stages, the initial heading of the plants and other factors. We just didn't expect it to happen this soon, though we knew we had a potentially risky outbreak."
The good news, if there is any, is that early applications of Dow AgroSciences' Transform WG are proving to be effective if applied correctly. The downside is an application increases input costs by about $6 an acre. EPA authorized a Section 18 to Texas Department of Agriculture for the use of Transform WG (sulfoxaflor) on sorghum to control the sugarcane aphid.
Sekula-Ortiz says using drops on spray booms and hollow cone nozzles to apply the chemical under the bottom leaves where aphids feed is the most effective treatment method. She also recommends using a surfactant to help ensure better coverage. A high rate of water, 10 to 20 gallons per acre for irrigated fields, is best.
"We are looking at the need for two applications for adequate control, and maybe a third application depending on the intensity of the problem in individual fields."
And that, she says, is the downside.
"Some of our larger producers in the Valley decided early on they wouldn't treat their fields because of the added costs. Some felt like they had weathered past aphid outbreaks, but over the last week or so they are beginning to understand this is not just an average outbreak of the yellow sugarcane aphid but an entirely new threat."
She advises that if scouting determines 40 out of 100 sorghum plants are infested by the new aphid, consider treating with Transform WG.
To add to concerns over the outbreak of the new white sugarcane aphid in sorghum fields across the Valley, Sekula-Ortiz says last week they began noticing winged varieties of the new aphid had migrated to corn and sugarcane test plots at the Weslaco research center.
After scouting commercial corn and sugarcane they began to spot aphids that had moved to these crops.