Quarter-plant samples to detect populations of Lepidoptera (Noctuidae, Pieridae, and Plutellidae) on cauliflower
1989
Stewart, J.G. | Sears, M.K.
Four methods of sampling eggs and larvae of imported cabbageworm, Pieris rapae (L.), and larvae of diamondback moth, Plutella xylostella (L.), and cabbage looper, Trichoplusia ni (Hubner), on cauliflower, Brassica oleracea var. botrytis L., were evaluated. Plants were sampled by examination of the leaf surfaces of one quarter, one half, or the whole plant, or by a destructive method. Plants that were treated biweekly with permethrin at 140 g (AI)/ha required 22% less time to sample and had 58% more P. rapae eggs per plant than did unprotected plants. Fewer cabbage looper equivalents (CLE) per plant per week were estimated with half-plant samples than with quarter-plant, whole-plant, or destructive samples. An efficiency index--the product of relative variability, number of CLE per plant, and sampling time--was greater for quarter-plant samples than for half-plant samples, relative to destructive samples. The quarter-plant sample was the most appropriate unit for sampling leaf-feeding insects on cauliflower.
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