Tolerance of Early Maturing Corn (Zea mays) Hybrids to DPX-79406

Abstract

The effect of DPX-79406 was evaluated on eight corn hybrids in 1993 and on 18 hybrids in 1994. Experiments were conducted each year at Charlottetown, Prince Edward Island, and Stewiacke, Nova Scotia. Corn tolerance was similiar between sites but varied from year to year with certain hybrids. Generally, tolerance was hybrid dependent. Most hybrids displayed chlorosis and stunting 7 days after treatment (DAT) but recovered quickly. Injury at 7 DAT ranged from 8 to 64%. Grain yield indicated that ‘Pickseed 2444,’ ‘Pioneer 3921,’ ‘Pioneer 3979,’ and ‘DK 302’ were tolerant to 25 g ai/ha of DPX-79406. Pioneer 3979 and Pickseed 2444 grain yields were reduced with DPX-79406 at 50 g/ha in 1 yr. ‘DK 291’ and ‘DK 235’ were severely injured both years and did not recover appreciably from early injury. Responses of ‘Pioneer 3984’ and ‘Pickseed 2477’ varied from year to year, and they were considered sensitive to DPX-79406. ‘Pioneer 3947,’ ‘Pioneer 3962,’ ‘Pickseed 2290,’ ‘Pickseed 2299,’ ‘DK 220,’ ‘G-4011,’ and ‘N0565’ were tested only 1 yr and were tolerant to both rates of DPX-79406.