Trash trees surrounding the field should be removed. Pecan trees that can not be adequately sprayed should be removed if they are susceptible to the scab fungus. Spores of the pecan scab fungus produced on the unsprayed trees are spread by air currents to surrounding trees. Sanitation measures such as removal of old shucks and leaf petioles from around trees wiil help to reduce disease inoculum in the orchard. If left in place, spores produced from old lesions are carried by air currents up to the tree.
Fungicides are an important part of the pecan disease management program.
Although some of the newer fungicides have post infection activity, they are most effective when applied as a preventive application. Thorough coverage of leaf, nut and shoot surfaces with a fungicide must be maintained to prevent infections. Brown leaf spot affects only mature leaves and does not appear until the latter part of May or mid-June. Primary lesions develop on the lower leaf surfaces as small dots which gradually enlarge and become reddish-brown with a gray cast. The shape of the lesions may be circular or irregular, especially where two or more lesions develop adjacent to each another.