Environmental Protection Agency emergency exemptions have been granted throughout the Southeast that hopefully will help sorghum producers in their battle against the white sugarcane aphid.
Mace Bauer, University of Florida/IFAS Extension agent in Columbia County, says the exemption is valid in his state until Dec. 31, 2014, and will allow for rescue treatments on late-planted sorghum. Bauer, along with entomologist Gregg Nuessly, was instrumental in spearheading the effort to obtain Section 18 Exemption in Florida. The exemption allows the use of Transform WG, a Dow AgroSciences product, for controlling the emerging insect pest.
Similar exemptions have been granted in Georgia and other states, with differing expiration dates. While Alabama did not obtain an exemption this year, officials there expect one to be in place for the 2015 sorghum crop.
“Unfortunately, we have been seeing area crops decline rapidly with the poor white sugarcane aphid (WSA) control offered by alternative control methods,” says Bauer. “Following the identification of sugarcane aphid infestations in forage sorghum in Columbia County on Aug. 21, we have been working to obtain this Section 18 Exemption for Florida farmers.”
The Florida situation was unique because there had not been a documented incidence of the pest attacking sorghum in Florida prior to the finding in late August, says Bauer, who adds that the rapid turnaround for the exemption is a result of many professionals treating this issue with the urgency it deserves.
“Agencies involved included University of Florida/IFAS, the Florida Department of Agriculture and Consumer Services, Dow Chemical, National Sorghum Producers, and several local farmers. Land grant universities in several other states also assisted. I can’t emphasize enough the professionalism and sense of urgency shown by all in expediting this arduous process,” says Bauer.
The recommended application rate for Transform WG is 1 to 1.5 ounces per acre, with a maximum seasonal application rate of 3 ounces per acre, he says. Research in Mississippi has indicated that multiple applications were required for complete control.
“I hope our efforts were timely to prevent crop failure of many fields,” says Bauer. “We at the University of Florida/IFAS along with the Florida Department of Agriculture and Consumer Services have our work cut out for us to have a supplemental label approved for the 2015 sorghum crop.”
The white sugar cane aphid is new, devastating pest this year in Florida sorghum, he says. It has moved in from Texas, Louisiana and Mississippi, and it also has been a major problem in Alabama and Georgia as well.
The only labeled treatments up until the emergency exemption was granted have been dimethoate and Lorsban (chlorpyrifos), neither of which have been providing adequate control of the white sugarcane aphid, says Bauer.
Growers must follow the Transform Section 18 label guidelines for the product, he emphasizes. “Farmers may be familiar with Transform because it has a label for use in cotton for aphid control. The Section 18 will expire in December of this year, however, UF/IFAS and FDACS are beginning efforts to allow use of this product in sorghum for the 2015 crop.”
Bauer notes that north Florida has a strong dairy industry that supports the livelihood of the region. “Sorghum grown for forage is an essential feedstock of the dairy industry, with the counties of Suwannee, Lafayette, Gilchrist and Levy producing approximately 20,000 acres of sorghum harvested for dairy cattle feed each year. This is primarily late planted behind spring crops, so it was much more susceptible to these aphid populations that developed late.”
In his scouting and communication with farmers, Bauer has found 100-percent infestation of white sugarcane aphids in area fields.
“Land grant universities throughout the Southern U.S. have indicated treatment thresholds of 200 to 300 aphids per plant. We have found levels estimated in the thousands of aphids per plant in most cases. Without acceptable control, my observations to date have shown that we can expect complete loss of the infested crop due to unsuitability for feeding to dairy cattle. The economic implications of a total crop failure include the loss of $8 million in input costs and the purchase of approximately $20 million in substitute feedstocks. Dairies also will suffer lost production due to using less-than-optimal replacement forages.”