Notes on Stone Fruit Insects &
Mites - Pears
Pear scab
Identification
Pear scab, caused by Venturia pirina, has a biology and disease cycle
similar to apple scab caused by Venturia inaequalis. The pathogen
that causes pear scab does not infect apples and vice versa.
Scab symptoms first appear as velvety black spots on young pear fruit.
Severely infected fruit drop prematurely. Infected fruit that remain on
the trees are often deformed with brown, scabby lesions. Under optimum
environmental conditions, the initial lesions produce spores that cause
secondary infection. Pinpoint scab lesions may develop on maturing fruit
late in the season or after they are placed in cold storage.
Management notes
Management strategies focus on the reduction of overwintering inoculum
in leaf litter and primary infections in the spring. Once primary infections
are controlled, secondary infection is also limited and the disease will
not become serious. Cultural practices that promote the rapid decomposition
of leaf litter on the orchard floor reduce the number of overwintering
spores.
For successful scab control during wet weather, apply fungicides in the
spring. Begin at green tip and continue through bloom, petal fall and
first cover.
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