Plant Health Problems
Diseases caused by Fungi:
Anthracnose or scab, Sphaceloma symphoricarpi.
Leaf spots appear in early spring on the leaves as small, dark purple to black dots which enlarge and develop grayish centers. Purple sunken spots develop on berries.
Control measures generally are not necessary, since this disease is not usually severe.
At least two kinds of aphids infest snowberry. If abundant, a spray of ultrafine horticultural oil, insecticidal soap or malathion, which are among the compounds registered for control of this pest in Connecticut, applied as a foliar spray will control them. Imidacloprid, applied as a soil drench early in the season, will provide systemic control. Consult the label for dosage rates and safety precautions.
San Jose scale, Quadraspidiotus perniciosus.
The San Jose scale infests snowberry. Large infestations of the San Jose scale can kill branches. Partially-grown scales overwinter under their circular gray covering or scale on the twigs. They begin to feed as the sap starts to flow. When apple trees bloom, the males emerge from under their scales to mate with the immobile females. Females are circular and cone-shaped, and their circular scales are about 1/16" in diameter, with a raised center or nipple. The males are smaller and elongate, with the nipple not centered on the scale. Females give live birth to tiny bright yellow crawlers in June, usually about 3-5 weeks after the flower petals drop. The young crawlers quickly settle, insert their long mouthparts into the twigs, and then suck sap from branches. As they grow, the crawlers secrete a waxy filament that becomes their scale or covering. Scales apparently have two generations per year, with the first in June and the second in August. Horticultural oil, is among the compounds registered for control of this pest in Connecticut. Horticultural oil is useful during plant dormancy or in the growing season when crawlers are active. To detect the yellow crawlers, wrap black tape coated with Vaseline around small branches. Consult the labels for dosage rates and safety precautions.
Snowberry clearwing, Hemaris diffinis.
The caterpillars of this moth feed upon snowberry and Tartarian honeysuckle, and are called hornworms because each has a horn on the tail like other sphinx moth caterpillars. There are two generations each season and the insects overwinter as pupae in the ground. The moths emerge in May and lay eggs on the food plant; the caterpillars feed until the middle of June, when they pupate. The moths soon emerge and lay eggs for the second generation of larvae. The caterpillars vary from dark green with lighter green on the back to brown or purplish, with spiracles very prominent. The moths have a wing spread of from 1 1/2 to 2". All wings are transparent with dark brown margins. The body is black marked with golden pubescence. If needed, spray with Bacillus thuringiensis var. kurstaki when the caterpillars are young. Malathion or spinosad can control larger larvae. The first generation larvae are found in May or early in June, while the second generation is active in July. These products are registered for use against this pest in Connecticut. Consult the label for dosage rates and safety precautions.