Using Classic Herbicide as a Growth Regulator in Peanuts

— Written By

Here is an abstract from some of Alan York’s work in the early 1990s with Classic on the variety NC 9.

Evaluation of Chlorimuron as a Growth Regulator for Peanut
Wayne E. Mitchem, Alan C. York, and Roger B. Batts
Peanut Science (1995) 22:62-66

Chlorimuron was evaluated as a growth regulator on peanut. Treatments included chlorimuron at a total of 8.8gai/ha applied once at 60, 75, or 90 d after emergence (DAE) or in equal portions applied twice at 60 and 75, 60 and 90, or 75 and 90 DAE or three times at 60, 75, and 90 DAE. Daminozide at 950 g ai/ha applied 75DAE was included as a comparison. In a year with excessive vine growth, daminozide and all chlorimuron treatments except 8.8 g/ha applied 90 DAE reduced cotyledonary lateral branch and main stem length at harvest 9 to 20 and 12 to 24%, respectively, due to suppression of internode length. Sequential applications of chlorimuron generally suppressed growth more than single applications. No improvement in row visibility at harvest was noted. In a dry year with limited vegetative growth, neither chlorimuron nor daminozide affected cotyledonary lateral branch or main stem length at harvest. Chlorimuron at 2.9 g/ha applied 60, 75, and 90 DAE reduced yield 18% at one of four locations; no other treatment affected yield. Chlorimuron at 8.8 g/ha applied 60 DAE or 4.4 g/ha applied 60 and 75 DAE reduced the percentage of fancy pods and extra large kernels at one or more locations. No treatment affected the percentage of total sound mature kernels. Results suggest chlorimuron has little to no potential for use as a growth regulator.

I decided to put a few trials with Classic applied at 0.5, 0.3, and 0.1 oz/acre at a few locations. Bottom line is that there is no need to apply Classic to manage growth. Daminozide is the product Kylar, and Kylar and Apogee influence plant growth in a similar manner as anti-gibberellins. Classic inhibits ALS in sensitive weeds and crops and is labeled for weed control in soybean. It is, however, legal in that there is a tolerance in peanut. But, it is recommended only for the control of Florida beggarweed as a salvage treatment and not management of vine growth.

Article first appeared as North Carolina Peanut Note (PNNC-2011-032)