How to Manage Pests

Pests in Gardens and Landscapes

Seasonal development and life cycle—Pear scab

Life cycleThe pathogen overwinters primarily in infected leaves on the ground. In spring, primary spores are carried by air currents or splashing water from the infected leaves to flowers, leaves, or fruit, where they germinate and cause infections. Overwintering twig lesions may also be an important source of inoculum in spring. New spores, or secondary spores, are produced on the infected leaf or fruit surface 8 to 17 days later, allowing further spread of the disease in the tree until conditions become too hot and dry. Infection occurs most rapidly between 55° and 75° F and leaves or fruit must remain wet continuously for a minimum of 9 hours for infection to occur. If spring weather is dry from the green tip stage of bloom through fruit set, scab will usually not be a problem.


Statewide IPM Program, Agriculture and Natural Resources, University of California
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