The brown leaf spot disease fungus _Cercospora fusca_ (Heald and Walf)
Rand affects only mature leaves and usually 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 grayish cast. The shape of the lesions may be circular or
irregular, especially where two or more lesions develop adjacent to one
another, Figure 2. In seasons favorable for brown leaf spot development
pecan trees may be completely defoliated within 3 to 4 months if the
disease is not controlled. Most pecan varieties which are maintained in
a vigorous state of growth are resistant to brown spot disease.
_Control._—See spray schedule, page 4.