Vein Spot

Gnomonia nerviseda

Leaves collected from a native pecan (Carya illinoensis K. Koch) in Mercer County, Illinois, had lesions identical to those of vein spot disease observed in Louisiana. Cultures of the fungus isolated from diseased leaves in Illinois were morphologically similar to the vein spot pathogen (Gnomonia nerviseda Cole) found in Louisiana. No in vitro sporulation ofthe pathogen has been observed. Greenhouse inoculation tests using mycelium as inoculum confirmed the pathogenicity of the Illinois isolates, and typical symptoms of vein spot disease developed within 30 days. Lesions on the infected foliage collected from Illinois and on pecan seedlings inoculated with isolates from the Illinois tissue occurred only on leaf veins, midribs, petiolules, and rachises, as is characteristic of vein spot disease. Visual inspection of native pecans in Mercer County suggests that vein spot is prevalent in that area. This is the first confirmed identification of pecan vein spot disease outside the southern United States and indicates that the disease exists near both the southern and the northern extremes of the native pecan range.

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