HERBICIDE SAFENERS AND ACTIVATED CARBON FOR RICE AND SORGHUM PROTECTION AGAINST MARGINALLY SELECTIVE HERBICIDES (ANTIDOTE, PROTECTANTS, RED RICE)

VONI ANUNCIACAO DE ANDRADE, Purdue University

Abstract

Weeds such as Echinochloa spp. and Leerxia hexandra in rice (Oryza sativa L.) are easily controlled by most of the grass rice herbicides. However, some close crop weed species, such as red rice (Oryza sativa L.var. fatua) requires specific approaches. Also selective chemical control of sorghum grass weeds is unsatisfactory, since most of the grass herbicides usually cause some injury to sorghum. In order to enhance crop tolerance to non-selective or marginally selective herbicides, two methods of crop protection (activated carbon and herbicide-safeners) were evaluated for rice and sorghum. The effect of these herbicides in the control of red rice was also evaluated. Under greenhouse conditions, activiated carbon applied in 2.5 cm bands over the row at 100 kg/ha, gave complete protection to white rice from 1.1 and 1.7 kg/ha of diuron, and the control of red rice was excellent. At 150 kg/ha, activated carbon partially protected rice against butachlor at 5 ka/ha and oxadiazon at 1.1, 1.7 and 2.3 kg/ha. Data from the greenhouse herbicide-antidote studies show that cyometrinil effectively protected white rice against early post-emergence applications of diclofop-methyl at 1.2 kg/ha, and red rice control was good. Cyometrinil was not effective against metolachlor. Results from the flurazole studies revealed that white rice was only partially protected by the antidote against alachlor and butachlor. Flurazole failed to protect rice from injuries of either sethoxydim or fluazifop butyl applied at early post-emergence. The third herbicide-safener, naphthalic anhydride (NA) provided good protection of rice against molinate at 3.4 kg/ha, and red rice control was excellent. NA also was very effective against thiobencarb at 9, 11 and 13 kg/ha. The control of red rice was over 80%. In further studies, NA gave marginal protection to rice against alachlor. Also not complete protection was observed against butachlor and diclofop-methyl. Sethoxydim, even with NA, caused severe injury to cultivated rice. The safening effect of naphthalic anhydride (NA), flurazole and cyometrinil on sorghum against some chloroacetamide and thiocarbamate herbicides, was evaluated during two growing seasons under field conditions. Alachlor and metolachlor reduced sorghum grain yield 40% when the crop was unsafened, and 5 to 10% when safened with flurazole or cyometrinil, NA protection was slightly lower. Of the thiocarbamate studied, only vernolate was partially countereacted by the antidotes, and yield reductions over 50% were verified in the remaining treatments.

Degree

Ph.D.

Subject Area

Botany

COinS