Safeners Reduce Corn (Zea mays) Chloroacetanilide and Dicamba Injury Under Different Soil Temperatures

The results of two experiments involving the effects of safeners on chloroacetanilide and dicamba injury in corn are reported here. The first experiment was conducted to determine whether MON-4660, CGA-154281, dichlormid, and MON-13900 would increase corn tolerance to alachlor, metolachlor, and acetochlor, respectively, over a range of soil temperatures (12 to 37 C). All three herbicides, particularly acetochlor, reduced corn shoot lengths at temperatures less than 32 C. The safeners effectively increased corn tolerance to their respective chloroacetanilide herbicide at all soil temperatures. However, acetochlor injury was not completely overcome by dichlormid or MON-13900 when temperatures were less than 27 C. The second experiment was conducted to determine whether these safeners would alleviate injury caused by chloroacetanilides applied with dicamba in sensitive (Pioneer 3320) and tolerant (Cargill 7567) corn hybrids at soil temperatures ranging from 17 to 27 C. Chloroacetanilides (4.5 kg ai/ha) plus dicamba (0.6 kg ae/ha) reduced shoot lengths in both hybrids, with acetochlor/dicamba combinations causing the greatest reductions. All four safeners increased corn tolerance to chloroacetanilide/dicamba tank-mixtures equally.