Molinate (S-ethyl hexahydro-1H-azepine-1-carbothioate) controls red rice (Oryza sativa) in the Burdekin Valley of North Queensland

Abstract

Molinate controlled red rice (Oryza sativa) in commercial rice (O. sativa cv. Starbonnet) giving an increasing response at rates of 3.6, 4.3, 5.0, 5.7, 6.4, 7.2, 7.9 kg a.i./ha in 1 summer and 2 winter crops. No crop injury was observed at any rate of molinate, and grain yield, grain moisture, 1000-grain weight, head counts, grain number per head, germination counts, percentage bran and head yield were not affected. In 2 experiments, the percentage of whole grain was not affected by the chemical but in 1 experiment percentage whole grain increased with the rate of chemical used. Molinate provides a substantial level of control of red rice in commercial rice but the response to the herbicide is variable. In some crops weed suppression up to about 50% control is all that can be achieved, but in other crops controls of >90% are achievable. With the low levels of infestation that usually occur in North Queensland these levels of control are acceptable.