TOLERANCE OF EARLY-MATURING CORN (ZEA-MAYS) HYBRIDS TO DPX-79406

The effect of DPX-79406 was evaluated on eight corn hybrids in 1993 an d on 18 hybrids in 1994. Experiments were conducted each year at Charl ottetown, Prince Edward Island, and Stewiacke, Nova Scotia. Corn toler ance was similiar between sites but varied from year to year with cert ain hybrids. Generally, tolerance was hybrid dependent. Most hybrids d isplayed chlorosis and stunting 7 days after treatment (DAT) but recov ered quickly. Injury at 7 DAT ranged from 8 to 64%. Grain yield indica ted that 'Pickseed 2444,' 'Pioneer 3921,' 'Pioneer 3979,' and 'DK 302' were tolerant to 25 g ai/ha of DPX-79406. Pioneer 3979 and Pickseed 2 444 grain yields were reduced with DPX-79406 at 50 g/ha in 1 yr. 'DK 2 91' and 'DK 235' were severely injured both years and did not recover appreciably from early injury. Responses of 'Pioneer 3984' and 'Pickse ed 2477' varied from year to year, and they were considered sensitive to DPX-79406. 'Pioneer 3947,' 'Pioneer 3962,' 'Pickseed 2290,' 'Pickse ed 2399,' 'DK 220,' 'Gr-4011,' and 'N0565' were tested only 1 yr and w ere tolerant to both rates of DPX-79406.