DAMAGE FUNCTIONS FOR MELOIDOGYNE-ARENARIA ON PEANUT

Microplot experiments were conducted in 1989 and 1990 to determine the relationship between yield of peanut (Arachis hypogaea) and inoculum density of Meloidogyne arenaria race 1. Nine inoculum densities were used, ranging from 0-200 eggs/100 cm3 soil (1989) or from 0-100 eggs/100 cm3 (1990), and each density was replicated 10 times. In 1989, higher final densities (mean of 1,171 juveniles [J2]/100 cm3 soil) were obtained in plots inoculated with 0.5 to 50 eggs/100 cm3 soil than in plots inoculated with 100 to 200 eggs/100 cm3 (313 J2/100 cm3 soil). In 1990, final densities of M. arenaria reached high levels (greater-than-or-equal-to 1,111 J2/100 cm3 soil) in all inoculated plots. Pod yield and dry weight of foliage at harvest were negatively correlated (P less-than-or-equal-to 0.05) with inoculum density in both seasons. In 1989, the relationship between pod weight (y) and initial density (x) was described by Seinhorst's equation, with y = 0.088 + O.91(0.90)(x-1) and r2 = 0.826. In 1990. the relationship was y = 0.22 + 0.78(0.97)(x-1) and r2 = 0.794. These equations suggest tolerance limits of approximately 1 egg/100 cm3 soil, which may require specialized methods, such as bioassay, for detection.