Scales on Red-Leaf Plum Trees
Red-leaf plum trees (Prunus cerasifera) are popular ornamental fruit plants that may become infested with scales. Scales damage plum trees by sucking the sap out of leaves, fruit and bark. It is important for gardeners to identify scale damage on their red-leaf plum trees in order to provide both cultural and chemical control methods. Does this Spark an idea?
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Scales
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There are thousands of different species of scales. Certain scales, such as the San Jose scales and Kuna scales, target and damage plum trees. Regions that receive moderate winter temperatures may experience up to five generations of scales a year. Gardeners may not notice their scale problem until populations reach a staggering rate. Limbs supporting a large scale population may ooze gum that drips down from overhead. To prevent an out-of-control scale population, monitor your red-leaf plum tree throughout the year.
Damage
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Red-leaf plum trees with scale infestations exhibit symptoms such as branch dieback, weakened branches, yellowing leaves, leaf wilt, defoliation, deformed plums and bark cracking. In addition, scales produce a sticky substance called honeydew which coats the entire red-leaf plum tree. Ants attracted to the honeydew infest the tree and protect scales from their natural predators. Plum trees with severe damage may decline in overall health. Mature red-leaf plum trees with damage to large limbs become a safety hazard.
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Cultural Treatment
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Prune off heavily infested red-leaf plum limbs, as suggested by the University of California. When removing branches, make a 45-degree downward pruning cut near the branch collar of the tree. The branch collar is the swelling that attaches the branch to the main trunk. Avoid cutting into the branch collar, because this part of the branch contains chemicals that keep diseases and decaying pathogens into the main part of the tree. Knock off scales using a strong stream of water to treat mild infestations.
Chemical Treatment
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Treat your red-leaf plum tree with dormant oil for moderate to high scale infestations. Apply the spray in May to kill scale crawlers before they mature. Cover the entire red-leaf plum tree with the dormant oil. Focus your energy spraying underneath the foliage where scales colonize. When applying dormant oil to your red-leaf plum tree, keep your tree watered. Water-stressed red-leaf plum trees may be harmed with dormant spray. Also, avoid using excessive amounts of dormant oil to prevent burning your plum tree.
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