How to Manage Pests

Pests in Gardens and Landscapes

Scab—Spilocaea and Venturia spp.

Fungal scabs affect many hosts. Spilocaea spp. commonly infect apple, pear, pyracantha, and toyon. Venturia spp. infect coffeeberry, cotoneaster, cypress, poplar, and willow. Olive green to black, circular, scabby or velvety spots appear on infected leaves, which may yellow or redden and drop prematurely. Scabby spots, often more sunken, may appear on fruit, which may crack or shrivel and drop. Shoots may die back if the disease is severe.

Identification of species | Life cycle

Solutions

Remove and dispose of fallen leaves in the fall. Fall foliar fertilizer (urea) applications on deciduous hosts hasten leaf drop and promote leaf decomposition, reducing the number of spores in spring. Avoid overhead sprinkling, which splashes spores onto the plant, or irrigate early in the day so that foliage dries more quickly. Sulfur, Bordeaux mixture, or narrow range oils applied about weekly to foliage during wet weather before disease develops can prevent the disease, but chemical control is generally not warranted, and is impractical on large trees, except where the disease is severe on apple or pear fruit. Vigorous plants tolerate extensive leaf scabbing, so provide plants with proper cultural care.

For apple scab, see the Apple Scab Pest Note.

Scab lesions on toyon leaves
Scab lesions on toyon leaves

Scabby spots on apples
Scabby spots on apples


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