Cristulariella pyramidalis

Author: Paul Bertrand, University of Georgia

Symptoms

Zonate leafspot begins as small, gray to light brown spots on the leaflets. These spots expand rapidly taking on a distinct target or banded appearance (Figure 6). Symptom development and leaflet drop occur rather rapidly. Leaflet drop may begin within a week of symptom appearance.

Disease Development

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. These sites tend to remain wet longer than open, level groves. If a grower has had trouble with zonate leafspot in the past, he should treat for it when long periods of continuously wet summer weather occur. Continuously wet weather is assumed to mean 4 - 6 days, but this has not been proven.