Rating Pecan Leaf Scab
Pecan scab [Cladosporium caryigenum (Ell. et Lang.) Gottwald],
Rate leaves (lamina only) in June and August using Hunter-Roberts scale (Pecan Quarterly 12(3):3-6). Rating is based on the single worst leaf seen. Only lesions on the lamina should be rated, in order to insure distinction between pecan scab and vein spot. Vein spot lesions are typically shiny, while scab lesions are typically look "dusty".