A Method of Estimating Insect Defoliation of Soybean

A linear relationship was shown to exist between the total area of the trifoliate soybean leaf and the product of length and width (widest point) of the terminal leaflet. The equation, area (cm2) = 0.018 × LW (mm), accurately estimated leaf area for 7 soybean varieties grown in the field; however, varieties reacted differently when grown in the greenhouse. A high degree of correlation existed between area determined by linear measurements of the terminal leaflet and area determined using an electronic area integrator. This nondestructive technique can be used in the field to determine percent defoliation caused by soybean insect pests.