The effect of density and intercropping with maize on early leaf spot of peanuts. L. M. Veilleux (1), M. A. BOUDREAU (1), and B. Shew (2). (1) Warren Wilson College, Asheville, NC; (2) North Carolina State University, Raleigh, NC. Phytopathology 89:S80. Publication no. P-1999-0573-AMA.

Twelve 10 × 10 meter plots were established in 3 completely randomized treatments with 4 replicates each: a high density peanut monocrop (HDM), a low density peanut monocrop (LDM), and an intercrop (INT) of peanuts and maize in which the peanuts were planted at the same density as in the LDM treatment. A focal epidemic was initiated by inoculation with Cercospora arachidicola and severity evaluated in 16 quadrats at 4 times to characterize spatial and temporal progress. Area under the disease progress curve (AUDPC) was reduced 50% in the INT treatment and 32% in the LDM treatment (P < .05) relative to the HDM treatment. AUDPC in the INT and LDM treatments were not different (P > .20) by the Tukey-Kramer test. Rates of disease progress based on a logistic model did not differ among treatments (P > .50). The results of this study indicate that intercropping does have an effect on severity of peanut early leaf spot. They further suggest that the reduction in severity is due to a decrease in host plant density and not to the presence of a non-host intercrop.