Abstract
The effect of foliage and nut diseases on some pecan cultivars was evaluated under field conditions at two locations. Western cultivar (one of the two main pecan cultivars) was the most susceptible to downy spot disease (Mycosphaerella carygena Demaree and Cofe) causing 140 spots per leaf and 42% defoliation in one location and 70 and 22%, respectively, in the sec· ond location. Fruits are not damaged by this disease. Pecan scab (Cladosporium caryigenum Ell et Lang Gottwald), in which nut damage was important, was another main disease. Cultivar Tejas which had 60% and 35% affected nuts was the most affected in both locations.