Most varieties can be attacked by powdery mildew, but Pabst, Wichita, Desirable and Farley are especially susceptible. If any of these varieties are present, they can be scouted for powdery mildew. Symptom development and leaflet drop occur rather rapidly. Leaflet drop may begin within a week of symptom appearance. Zonate leafspot occurs on mature leaves.
All pecan varieties are susceptible to zonate leafspot.
However, Schley appears to be more susceptible than Stuart. The disease is most common in Calhoun, Dougherty, and Lee counties. It has been seen in other areas of the state. In years when it occurs, its incidence may be very erratic from grove to grove. Zonate leafspot has been observed to be more severe in trees bordering woods or in low areas of groves.