Chokecherry (Prunus virginiana) is a large shrub or small tree with shallow suckering roots. It grows 12 to 25 feet tall and 10 to 20 feet wide. The creamy white flowers are followed by dark red or purplish-black fruit, which is used for jellies, jams and wines.
The Amur Chokecherry (Prunus maackii) also bears edible fruit, which is black. It has an upright form and amber to orange peeling bark. Both varieties are susceptible to numerous diseases.
Black Knot
Black Knot is a common and serious fungal disease caused by Dibotryon morbosum on Chokecherry trees. Hard, black, elongated, swollen areas form on the smaller branches and may grow up to 1 foot long. Eventually the swollen area girdles and kills the infected branches. Severe infections may affect the main branches and trunks of Chokecherry trees but will not girdle them.
To control the spread of Black Knot, remove the infected area and 4 to 5 inches of healthy tissue below the infected area in the spring before bud break. Burn or bury the diseased branch to prevent the spread of infection. Apply a fungicide for Black Knot on Chokecherry trees at the rate recommended by the manufacturer.
Leaf Spots
Bacterial leaf spots or shotholes on Chokecherry trees are caused by Xanthomonas pruni or Pseudomonas syringae. Water-soaked spots appear on the underside of infected leaves. The spots turn brown or black as the disease progresses, and the center of the hole may fall out, leaving a red margin around the hole. Leaves that develop numerous spots yellow and drop early. Premature defoliation reduces the size of the fruit and weakens the tree. The disease also may affect the fruits, which develop dark or reddish brown spots and sunken areas.
Chemical treatments usually are not effective on leaf spots or shotholes. To reduce the risk of infection, do not plant Chokecherry trees near other diseased trees and avoid excessive amounts of nitrogen in fertilizers.
Perennial Cankers
Two fungi, Valsa cincta and V. leucostoma, cause perennial cankers to form on the branches and trunks of Chokecherry trees. The cankers are oval areas of dead tree tissue surrounded by a roll of callous tissue. Perennial cankers get larger each year and may girdle and kill infected branches or trunks.
The fungi enter the tree through wounds, so avoid mechanical injuries to the trees and prune in the spring for faster healing. Do not plant Chokecherry trees in a waterlogged area or near diseased trees. A fungicide for perennial cankers on Chokecherry trees applied according to the manufacturer's instructions may control the canker's growth.
Plum Pockets
Several Taphrina fungi cause the fruit of Chokecherry trees to become hollow and swell up to 10 times their normal size. These pockets, as they are called, turn various colors, from greenish-yellow to bright red. Leaves infected by Taphrina curl up, and young shoots become enlarged and deformed.
The disease may cause a major loss of fruit. Apply a fungicide for Taphrina fungi on Chokecherry trees according to the rate and schedule recommended by the manufacturer to reduce the severity of the disease.
Tags: Chokecherry trees, Black Knot, branches trunks, Apply fungicide, branches trunks Chokecherry, Chokecherry Prunus
