Propanil and Molinate for Control of Barnyardgrass in Water-Seeded Rice

Abstract

The herbicides, S-ethyl hexahydro-1 H-azepine-l-carbothioate (molinate) applied preemergence and 3′,4′-dichloropropionanilide (propanil) applied as a contact spray at several dates, were evaluated for control of barnyardgrass (Echinochloa crusgalli (L) Beauv.) in water-seeded rice (Oryza sativa L., var. Caloro) flooded continuously to a shallow (3 inch) depth. Propanil applied when barnyardgrass had 6 to 9 inches of leaves exposed gave higher yields than earlier or later applications. Molinate gave the best barnyardgrass control when it was applied as a granule, incorporated, and applied onto dry soil. Molinate controlled the three major phenotypes of barnyardgrass. Germinating barnyardgrass seed were severely inhibited in growth by molinate concentrations greater than 0.3 ppm while germinating rice seed were not inhibited until the concentrations were greater than 5 ppm. Low concentrations of molinate stimulated shoot growth of both rice and barnyardgrass.