Regular scouting should provide early clues to problems of this nature. With heavy infection, the lesions may grow together resulting in large irregular black areas on leaflets or nuts. Early lesions may grow together resulting in large irregular black areas on leaflets or nuts. Old lesions, particularly in late season, are often overgrown by other fungi, giving them a white moldy look. The pecan scab fungus overwinters on shucks and shoots infected the previous season.
Infections can occur as soon as green tissue appears in the spring.
They continue to occur throughout the season on any growing tissue. The value of prepollination disease control was known before 1930. Prepollination leaf infections arise from overwintering inoculum. Most of the inoculum available for infection of the nut crop in June and July arises from early leaf infections. Pecan scab seldom causes significant leaf drop though leaf infection may be common.