A healthy plum tree will be covered in blossoms during its flowering stage. As the blossoms pollinate, plums develop and grow. Though plum trees are easy to care for, they are quite susceptible to disease. Early detection, especially in flowering plum trees, is extremely important and can, in some cases, prevent the death of the tree.
One of the most common plum tree diseases is Black Knot, which causes hard, black and elongated swellings on plum tree branches. The infection generally appears in the spring. The initial infection appears on smaller tree branches as olive-green knots that have velvety surfaces. While the “knots” vary in size, some can be more than a foot in length. Black knot can spread to the tree’s main branches or trunk if untreated. Treat and prevent black knot with regular pruning and fungicide treatments.
Peach Leaf Curl
Peach Leaf and Plum Pocket are commonly referred to simultaneously because their symptoms and treatments are similar. Peach Leaf Curl is a peach tree disease that often affects plum and nectarine trees. This fungal disease attacks the leaves of the tree, causing them to curl and crinkle inward from the outer edge. The fungus also causes the production of powdery looking spores that appear silvery and grayish. As the disease progresses, the leaves brown and fall. The infection will slowly spread to branches and fruit, if untreated
Like Peach Leaf Curl, Plum Pocket is a fungal disease that causes the leaves to wilt and curl. The disease can cause damaging fruit loss and branch injury. Unlike Peach Leaf Curl, this disease affects only plum trees. Both Peach Leaf Curl and Plum Pocket can be treated with an application of fungicide.
Verticillium Wilt is a common disease that attacks the plum tree through its root system. This disease is caused by a soil-borne fungus and causes the tree to show wilt from the bottom, up. This disease stunts the tree’s growth and causes its leaves to wilt. Usually, infected trees can't be saved. This disease is common in soil that was used for potato and vegetable growth. There is no cure or treatment. If you remove the tree because of this disease, do not replant immediately in the same soil.
Brown Rot is a fungal disease that can infect all fruit trees. When plum trees are flowering, Brown Rot attacks the blossom and passes through to the cluster, attacking the fruit itself. Brown Rot initially causes light brown circular spots on the fruit blossom and will eventually cause cankers on branches and twigs. The attacked fruits and blossoms will wither and rot. Brown Rot can be treated if addressed in a timely fashion. Treat the brown rot by removing dead fruit, pruning branches, and using a fungicide spray.