This pest only reproduces once per year, with the egg hatch occurring in early to mid June over an approximate ten day period. Make your first application of insecticide when Spiraea x vanhouttei (the old-fashioned, cascading variety) has just finished blooming. It attacks many species of shade trees including apple, white ash, white elm, basswood, and red maple. The oystershell scale occurs generally throughout Canada and the United States. Light infestations do not exhibit obvious symptoms; Severe infestations can cause chlorotic, stunted foliage; Dieback and cracked bark can result from heavy infestations; Light to dark brown, elongated, 1/10 to 1/8 inch long oyster-shell shaped scales found on bark. In case of emergency Call your poison control center: 1-800-222-1222 If the patient has collapsed or is not breathing: call 9-1-1 Pesticide Safety Information Hosts—Oystershell scale has been recorded on over 125 species of plants, mostly hardwoods, and is most commonly found on aspen and other poplars, ash, maples, willows, and lilac. They occur less frequently on the leaves and other plant parts. My neighbor’s lilacs, while showing signs of lilac blight earlier in the season, continue to experience massive dieback. Hosts: Beech, birch, maple, ash, poplar, willow, elm, lilac, apple, pear, cherries and many other plants. Oystershell scale is a very common pest on aspen. Relative Disease Susceptibility and Sensitivity to Sulfur, Diagnosis and Control of Phytophthora Diseases, APHIS List of Regulated Hosts and Plants Proven or Associated with Phytophthora ramorum, Plants Resistant or Susceptible to Armillaria Root Rot, Verticillium Wilt in the Pacific Northwest, Plants Resistant or Susceptible to Verticillium Wilt, Plants Susceptible to Sclerotinia sclerotiorum, Potential Impact of Cyanobacteria on Crop Plants, Management of the Cyanobacterium Nostoc in Horticultural Nurseries, Impatiens Necrotic Spot: New Name, Same Threat, Virus Certification Program for Fruit and Ornamental Trees, Care and Maintenance of Wood Shingle and Shake Roofs, Winter Injury of Landscape Plants in the Pacific Northwest, Recognizing Sapsucker Damage on your Trees, Key to Nutrient Deficiencies in Vegetable Crops, Key to Nutrient Deficiencies of Deciduous Fruit and Nuts, Use of Disinfestants to Control Plant Pathogens, Current Status of Biological Weed Control Agents in Idaho, Oregon, and Washington, Biological Control Agents and Their Roles, Restricted-use Herbicides in Idaho, Oregon, and Washington, Testing for and Deactivating Herbicide Residues, Herbicide Effectiveness on Weeds in Grass Seed Crops, Dry Bean East of the Cascades - Phaseolus spp. The oystershell scale is a common insect pest in Iowa. Oystershell scale is a hardshell scale, meaning that insects develop a hard, protective covering over themselves that is difficult to penetrate with insecticides. Management of oystershell scale. Pine Needle Scales. Oystershell scale are found on trunks, branches, and twigs of many broad-leaved deciduous plants. OYSTERSHELL SCALE Lee Townsend, Extension Entomologist Oystershell scale is a common armored scale that can infest more than 100 pl ant spec ies. Some gardeners aren’t even aware the insects are present as they prune out dead branches the insects have killed. Its infestations are common in ornamental plantings where trees are subject to various stresses. oystershell scale. This species is so called because their armor resembles the shell of oysters. They suck the juices from young stems, killing them and causing defoliation. Biological predators emerge too late to be effective. Ash-lilac borer and oystershell scale have been causing dieback in lilacs in recent years. Of the shrubs, lilac is perhaps most frequently infested. The oystershell scale is a small (1/20 to 1/8 inch long), elongated, oyster-shaped insect. Oystershell scale is considered a serious pest on Cotoneaster shrub- which is a popular choice for hedges in our city. Of these, ash, cotoneaster, dogwood, lilac, poplar and willow are most commonly infested. Oystershell scale can be found on ash, maple, lilac, cotoneaster, dogwood, poplar, willow; fruits such as apple, pear, apricot, plum, raspberry, currant and grape; and many other hardwood trees and shrubs. The insect overwinters as an egg under its mother's shell. Lilac borers, as the name suggests, burrow into the wood of the plant, sometimes leaving small … Homoptera: Diaspididae. Life History There are two races of the oystershell scale; the gray race which is found on lilac, ash, willow, poplar, and maple while the brown race is found on apple, dogwood, and poplar. 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