The Influence of Weather on the Response of Potato Cultivars to Metribuzin1

Abstract

Abstract The response of 11 cultivars of potato (Solanum tuberosum L.) to preemergence, preemergence + postemergence, and early postemergence applications of metribuzin [4-amino-6-ferf-butyl-3-(methylthio)-as-triazin-5 (4H)-one] was studied over a 5-year period (1973–1977). Postemergence sprays applied at temperatures over 21°C increased injury and decreased yields. ‘Belleisle’, ‘Early Rose’, ‘Kennebec’, ‘Netted Gem’, ‘Red La Soda’, ‘Red Pontiac’ and ‘White Rose’ were more sensitive to metribuzin at these temperatures than ‘Epicure’, ‘Norgold Russet’, ‘Norland’, and ‘Warba’. Cultivars responded to the amount of sunshine before, during, and after spraying with metribuzin. When the weather was very cloudy on the 3 days before and on the day of spraying and then sunny for the next 3 days, metribuzin injured ‘Belleisle’, ‘Netted Gem’, ‘Red Pontiac’, and ‘Warba’. ‘Belleisle’, ‘Epicure’, ‘Norland’, ‘Red La Soda’, ‘Red Pontiac’ and ‘White Rose’ when grown under stress caused by lack of water, were more sensitive to the herbicide than the other cultivars under test. ‘Epicure’, ‘Netted Gem’, ‘Norgold Russet’, ‘Norland’ and ‘Warba’ grown in wet soil were more sensitive to preemergence applications than other cultivars. Cultivars differed in their tolerance to metribuzin and were classified as follows: ‘Norgold Russet’ and ‘Epicure’, most tolerant; ‘Kennebec’, ‘Early Rose’, ‘Netted Gem’, ‘Red La Soda’ and ‘Norland’, intermediate; and ‘Belleisle’, ‘Red Pontiac’, ‘Warba’ and ‘White Rose’, most susceptible.