Differential susceptibility of potato cultivars to four herbicides

Greenhouse and field studies were conducted to evaluate the susceptibility of six potato (Solatium tuberosum L.) cultivars to injury by four herbicides. The White Rose cultivar was the most susceptible to injury, especially from metribuzin {4-amino-6-tert-butyl-3-(methylthio)-s-triazin-55 (4H) one}, and linuron {3-(3,4-dichlorophenyl)-l-methoxy-l-methyl-urea}. Injury was attenuated by decreasing the rate of herbicide in the range of 4.5 to 0.5 kg/ha (4 to 0.5 1b/A) and by increasing the seed piece size. Injury seemed to be associated with soil texture and was greater in a sandy loam than in a sandy clay loam soil. Greenhouse studies provided valuable leads on cultivar susceptibility to herbicides but reductions in foliar weight of 15 to 20% are required to justify any suspicion that field injury will occur.