Eight sweet corn cultivars were evaluated for tolerance to AE F130360 in five field experiments conducted over 2 yr in Ontario. AE F130360 was applied postemergence at 70 and 140 g ai/ha, the latter rate representing a spray overlap in the field. Response to AE F130360 varied with respect to sweet corn cultivar and herbicide rate. Minimal crop injury was observed in seven of the eight cultivars. One cultivar, ‘DelMonte 2038’, was extremely sensitive, showing 94% or more injury for all site-years. Plant height of most cultivars was not negatively affected by AE F130360 treatments, with the exception of DelMonte 2038, which sustained height reductions of 78% or greater compared with the untreated control. The crop injury and height reductions that were observed in DelMonte 2038 were reflected in the marketable yields, which were reduced by 92% or more as a result of the AE F130360 treatments. Marketable yields also tended to be reduced in ‘Calico Belle’ and ‘Rival’. On the basis of marketable yields, it was concluded that ‘CNS 710’, ‘GG 222’, ‘GG 246’, ‘GH 2684’, and ‘Reveille’ have full tolerance to AE F130360, Calico Belle and Rival tend to have moderate tolerance, and DelMonte 2038 has zero tolerance to AE F130360.

Five sweet corn cultivars were evaluated for tolerance to bentazon in five field experiments conducted during 2 yr in Ontario. Bentazon was applied postemergence (POST) at 1.08 and 2.16 kg ai/ha, the highest registered rate and twice the highest registered rate, respectively, used in sweet corn in Ontario. When bentazon was applied POST at 1.08 and 2.16 kg/ha to sweet corn cultivar ‘DelMonte 2038’, injury included plant stunting and leaf damage ranging from 6 to 69% and 15 to 90%, respectively. Plant height was reduced to 48 and 100% of the untreated check when treated with bentazon at 1.08 and 2.16 kg/ha, respectively. The visual injury and height reductions were reflected in the marketable yields, which were reduced to 94% when treated with bentazon. Significant reductions in height and marketable yield were not observed in the other four cultivars tested. No correlation was observed between bentazon sensitivity and endosperm genotype. Based on visual injury ratings, sweet corn height, and marketable yield, it was concluded that ‘Calico Belle’, ‘GH 2684’, ‘Reveille’, and ‘Rival’ are tolerant to POST application of bentazon.

Limited information exists on sweet corn tolerance to postemergence (POST) applications of clopyralid under Ontario growing conditions. Eight sweet corn hybrids were evaluated for tolerance to clopyralid in three field experiments conducted in 2001 and 2002 in Ontario. Clopyralid was applied POST at 200 and 400 g ai/ha, the proposed and twice the proposed registered rate for use in sweet corn in Ontario. Sweet corn response to clopyralid did not vary among the hybrids tested. In 2001, visual injury among hybrids 7 d after treatment (DAT) with clopyralid at 400 g/ha was less than 3%. Subsequent visual injury evaluations at 14 and 28 DAT showed no differences among sweet corn hybrids at either rate of clopyralid evaluated. The application of clopyralid at 200 and 400 g/ ha had no detrimental effect on plant height or marketable yield of any of the eight sweet corn hybrids. On the basis of visual injury, height, and marketable yield response ‘Calico Belle’, ‘CNS 710’, ‘DelMonte 2038’, ‘GG 222’, ‘GG 246’, ‘GH 2684’, ‘Reveille’, and ‘Rival’ are all tolerant to the POST application of clopyralid.