Identification and survival of the causal organism of leaf smut disease of cowpea in Nigeria.

Protomycopsis phaseoli (Ramak and Subram) is the causal agent of the cowpea leaf smut disease in Nigeria and not Entyloma vignae as claimed by some authors. This pathogen formed dark ash-grey to sooty-black lesions of 3-10 mm in diameter, while young lesions had yellow haloes. P.

Influence of Season and Cropping System on Occurrence of Cowpea Diseases in Uganda.

An on-farm survey was conducted for two seasons (first and second rains of 1994) to determine influence of season and cropping systems on occurrence of cowpea (Vigna unguiculata) diseases in Uganda. Viral diseases were widespread in both seasons but were more severe in the intercropped than in the nonintercropped cowpea. In contrast, scab, rust, and powdery mildew were less common and less severe when cowpea was grown in intercrops.

Reproduction of Pratylenchus penetrans on Potato and Crops Grown in Rotation with Potato.

The relative suitability of potato and crops frequently grown in rotation with potato as hosts for Pratylenchus penetrans was evaluated. Suitability of rye, wheat, corn, oat, sorgho-sudangrass, and potato were compared in pot studies based on ratios of final population : initial population density and densities of nematodes in roots at harvest. Population densities increased more on potato, oat, and corn than on rye, wheat, and sorgho-sudangrass.

Influence of Edaphic Factors and Previous Crop on Pratylenchus spp. Population Densities in Potato.

Root and soil samples from commercial potato fields were assayed for nematodes in 1983 and 1984. Pratylenchus spp. population densities in Suffolk County, New York, were consistently, though not always statistically, higher in potato fields that had been planted to rye or wheat rather than potatoes during the previous growing season.