Rice Production in Mississippi
Permit receives label for use in rice
Permit (Halosulfuron-methyl), a selective postemergence herbicide from Monsanto, has received a label for use in rice. The following are perceptions on the use of Permit. You may have heard the name "Sempra" which was proposed for this product, but Monsanto has decided to market it as Permit which is used in other crops such as corn and milo.
Most of my experience during the past 4 years of research with Permit involved nutsedge, which is effectively controlled. Because few other weeds grow in a dense nutsedge infestation, I have not evaluated Permit on a wide variety of weeds. The label contains several other rice weeds such as cocklebur, redroot pigweed, and smartweed . Preliminary results indicate that Permit will also control hedge hyssop and Mexican/Texas weed.
Rice tolerance to Permit is very good. I have never seen injury to dry seeded rice from Permit at any application timing. Permit may be applied from prior to planting up to establishment of the permanent flood. It is not labeled for post-flood application. Permit may be tank-mixed with preplant burndown herbicides to increase nutsedge control. At the low rates, Permit has limited residual activity, thus two applications may be necessary to control weeds that emerge after application. Do not apply more than 1.33 ounces per season.
Permit is in the sulfonyl urea family of herbicides such as Londax, thus its activity will be slow. For best results, apply Permit to actively growing weeds. The level of weed control will be dependent upon application rate, weed size, and growing conditions at the time of application. Soon after Permit application, weeds stop growing, but have no visual symptoms. Initial symptoms include a general discoloration (yellowing) of the leaves. Complete control usually occurs within 10 to 14 days after application.
Application to rice may be made by ground or air. Ground applications should be made in 10 or more gallons of spray solution per acre and aerial application in 3 or more gallons per acre. As with any herbicide, drift should be avoided especially around sensitive crops such as cotton.
The proposed label rate is 0.67 to 1.33 ounces of product per acre. When used alone, lower rates will control nutsedge. Higher rates may be required for other weeds. When tank mixing with other herbicides, especially propanil containing herbicides, the 0.67-ounce rate has provided effective control of nutsedge. Permit may be applied in combination with any other product registered for use in rice.
A nonionic surfactant, or crop oil concentrate (COC), should be used with Permit. Use a nonionic surfactant at 0.25 to 0.5 percent (1 to 2 quarts per 100 gallons of spray solution) or COC at 1 percent (1 gallon per 100 gallons). Liquid nitrogen solution or spray grade ammonium sulfate may be added to the spray solution if it is necessary for the tank mix companion herbicide. Add the surfactant and the other adjuvants as the last ingredients in the tank.