The Mississippi Bureau of Plant Industry submitted a request to the EPA April 19 asking for an emergency use permit for the pesticide Valor.

According to the request, Valor is needed to control pigweed and other weeds at layby in cotton because the canceled production of cyanazine products, including Bladex, leaves a shortage of acceptable, economical alternatives for the requested use. Valor is a Valent product which contains the active ingredient flumioxazin.

“The short residual for cyanazine provided more opportunity for rotational crop establishment of fall cover crops and/or fall grain crops such as wheat. It is also less restrictive for following-year crops such as corn and grain sorghum,” the application says. “The only fully registered alternatives for cyanazine replacement are diuron, prometryn, clomazone, fluometuron, pendimethalin and norflurazon. Each of these products has longer rotational crop intervals of most of the economically important crops in the Mississippi Delta, especially diuron, norflurazon and clomazone.”

“Economically, cyanazine averages about $7 per acre for layby applications. At $7.42 per acre, diuron is the most economical alternative, but is also more restrictive, rotationally, than other more costly, but less restrictive products that range in cost from $8.90 per acre (fluometuron) up to $10.58 per acre (prometryn),” says Tommy McDaniel, director of the Mississippi Bureau of Plant Industry.

Another reason cotton growers need Valor for the control of cotton weeds at layby, McDaniel says, is that pigweed is not easily controlled with the commercial products that are currently available to farmers, with the exception of cyanazine, which is expected to be in short supply.

“Changes in crop production systems for cotton from intensively tilled systems utilizing trifluralin to conservation tillage production systems that cannot utilize trifluralin have resulted in greater acreage being infested with pigweed,” the application to EPA says. “Since layby applications are fairly late in the season, use of diuron would only allow cotton to be grown the following season.

“Establishment of cover crops is becoming increasingly important with respect to soil erosion reductions and subsequent improvements in water quality. Also, crop rotations and changes in cropping systems have allowed better risk management in farm operations. Anything that places limitations on subsequent cropping alternatives is undesirable due to less flexibility in managing farm risks,” McDaniel says. “Based on current research, pigweed control with Valor is equal to that of cyanazine and superior to that of other alternatives.”

McDaniel says other states have expressed interest in obtaining a Section 18 permit for Valor, but so far only Mississippi has officially made the request to EPA.

It is estimated that about one-third, or 450,000 acres, of the state's 2001 cotton acreage could require treatment for the control of pigweed and other cotton weeds at layby.