The efficacy of the safeners naphthalic anhydride (NA), CGA-92194, and CGA-133205 as protectants of grain sorghum and of NA, R-29148, CGA-154281, and dichlormid as protectants of corn against injury from the chloroacetamide herbicide, SAN 582H, was evaluated under greenhouse conditions. SAN 582H applied alone reduced the shoot growth of ‘Funk G522DR’ and ‘Funk G623’ sorghum, but had no effect on the growth of the ‘GP-10’ genotype of sorghum. Corn (‘Northrup-King 9283’ hybrid) was considerably more tolerant than grain sorghum to SAN 582H. The rate of SAN 582H causing 50% reduction of corn shoot height (GR50) was 5.1 kg/ha as compared to 1.1 kg/ha for grain sorghum. NA applied as seed dressing at 5 or 10 g/kg seed, provided moderate protection to ‘G522DR’ and ‘G623’ sorghum and no protection to corn against SAN 582H injury. Dressing of sorghum seeds with CGA-133205 provided moderate protection to G522DR sorghum, whereas seed-applied CGA-92194 provided moderate protection to G623 sorghum against SAN 582H. The dichloroacetamide safeners R-29148, dichlormid, and CGA-154281 were all effective as protectants of corn against SAN 582H injury. These results demonstrate that, as with other chloroacetamide herbicides, the tolerance of corn and grain sorghum to SAN 582H can be enhanced with the use of safeners of the dichloroacetamide type and oxime ether type, respectively.

Benoxacor, CGA-185072, and MON-13900 were evaluated in laboratory studies as safeners to reduce injury caused by primisulfuron when corn has been previously treated with terbufos. Without safeners, shoot length was reduced 30% when primisulfuron (78 gm ha-1) followed terbufos (2.6 kg ha-1) applications. Stunting was significantly reduced by preemergence applications of CGA-185072 and MON-13900 at 200 g ai ha-1; however, shoot length was still reduced by 21 and 12%, respectively. Benoxacor did not reduce primisulfuron injury in corn previously treated with terbufos. Safening by CGA-185072 and MON-13900 was not due to reduced primisulfuron uptake or altered translocation. MON-13900 was further evaluated for its effects on primisulfuron metabolism. MON-13900 increased primisulfuron metabolism in terbufos-treated shoots by more than 50%. This increase in metabolism appears to be the mechanism of safening by MON-13900.