Selected Preharvest Morphological Characteristics of Soybeans Stressed by Simulated Green Cloverworm (Lepidoptera: Noctuidae) Defoliation and Velvetleaf Competition1

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Abstract
The separate and combined effects of velvetleaf, Abutilon theophrasti (Medic.), competition and simulated green clover worm (SGCW), Plathypena scabra (F.), defoliation on soybean Morphological development were evaluated in a 3-year field study. Statistical confirmation of velvetleaf competition stress was limited to soybeans in weed-proximate positions. Preharvest, weed-induced reductions in nodes with unrolled and fully developed leaves (1981 only) and transient effects on leaf area development were statistically significant. In comparison, the SGCW defoliation procedure consistently reduced soybean leaf area, height, and preharvest lodging scores. Nodal development and lower-leaf abscission lagged slightly in 1980 defoliated plots. Defoliated plants did not exhibit ‘compensatory regrowth.’ No treatment altered soybean stand counts, branching, reproductive phenology, or gravimetric soil moisture Determinations significantly. Actual statistical confirmation of velvetleaf × SGCW treatment interaction swash not achieved in this study.