Effect of Defoliation at Specific Growth Stages on Potato Yields

Abstract

Defoliation of ‘Superior’ and ‘Russet Burbank’ cultivar potatoes by the Colorado potato beetle, Leptinotarsa decemlineata (Say), and the variegated cutworm, Peridroma saucia (Hübner), was simulated by hand defoliation in a 2-year field study. ‘Superior’ and ‘Russet Burbank’ cultivars were defoliated at four and five different plant growth stages, respectively, during the growing season, with defoliation levels ranging from 10 to 75%. Defoliation during the full bloom period resulted in greater yield reductions than defoliation before or after full bloom. Defoliation of > 10% of the upper leaves on ‘Superior’ and ‘Russet Burbank’ cultivars during full bloom resulted in significant yield loss. Also, 10% lower leaf loss during full bloom on ‘Russet Burbank’ plants resulted in yield loss. Single-event defoliation thresholds for ‘Superior’ and ‘Russet Burbank’ cultivars are proposed.