3 photos. Bacterial blight. These trees are susceptible to various problems and diseases, including fungal attacks. Consider taking preventive measure -- proper spacing for good air circulation and avoiding excessive watering -- to keep the fungus from attacking the magnolia. Cause Pseudomonas syringae pv. General Information on Magnolias. Once inside, the bacteria induce a watery, nutrient rich environment between the plant cells where they can multiply and continue colonization of the plant tissues. Generally, leaf spot diseases can be tolerated if the magnolia tree is healthy. Bacterial blight tends to affect woody plants like trees and shrubs. Cause Pseudomonas syringae pv. Bacterial Blight can attack a wide range of trees and is most aggressive during mild, moist growing conditions. However, they are susceptible to a few forms of pests, like scale or weevil, and a handful of diseases caused by fungus or bacteria. In some cases, the center of the leaf spot will dry up and fall out, giving the leaf a "shot hole" appearance. Anthracnose. This bacterial infection causes the infected wood to become water-soaked with bacterial ooze. Growth Rate: The growth rate of magnolias depends on the species. causes bacterial leaf spot on magnolia. Rake up and dispose of infected leaves. In severe cases, these discolored leaves may fall from the branches prematurely. Each has the same magnolia disease symptoms: spots on the leaves of the tree. syringae, a bacterium favored by cool, wet weather in spring. Ornamental Features: Most magnolias are valued for their showy, fragrant flowers, large glossy leaves and striking fruit. The liquid is colorless or pale while inside of the tree, but darkens when exposed to air. Magnolias are so tough that many tree owners will never notice any real problems throughout their tree’s life, but when a sick magnolia tree is identified, the causal agent may be serious. Amanda Flanigan began writing professionally in 2007. Shoots, twigs or branches can be vulnerable to fungal cankers. There are three diseases in the diagnostic list. Discard shriveled and discolored seed. Pestalotiopsis blight. 48-hr reentry. Canker diseases will kill branches. Group M1 fungicide. This ooze seeps through the infected wood, causing the bark to discolor, crack and decay. Damage otherwise depends on the host plant and strain of P. syringae bacterium and whether infection occurred through blossoms, buds, or wounds in other tissues. It is found on almost all plants and causes a wide variety of diseases. Leaf spot diseases. 2 photos. The most common diseases of sweetbay magnolia are leaf spot diseases, fungal or bacterial. Large, dark, irregular spots also may be on leaves and have been reported on flowers. Spots enlarge and may be limited by leaf veins becoming angular in shape. It is fungus disease that attacks most of the young magnolia trees. Clemson University Extension: Magnolia - Magnolia spp. Promoting a healthy growing environment is the best way to prevent your plants from picking up this disease. Jane magnolias are susceptible to diseases resulting from both bacteria and fungi. Bacteria resistant to copper products and antibiotics have been found in Pacific Northwest nurseries. Bacterial blight is caused by the bacterium Pseudomonas syringae, which infects a number of different trees, including magnolias, as well as lilac, apricot, flowering cherry and dogwood. The vascular tissue can be adversely affected by verticillium wilt, caused by soil-borne fungi. Leaf spots are small, dark brown, water soaked, and often surrounded by a yellow halo. Magnolia tree leaf diseases can typically be controlled with proper care. Photo by Jay W. Pscheidt, 1992. © Copyright 2020 Hearst Communications, Inc. Bacterial spot. Algal leaf spot. Manager of the Diagnostic Cinic and works on a daily basis in identifying the cause of plant diseases (fungi, bacteria and viruses) in infected plant samples in crop production in North Florida, and communicates with farmers, extension agents, crop consultants and master gardens to share diagnsotic information. Consult the ManKocide label for specific rates and timing of application by crop. In some plants, it doesn't cause widespread damage, but it can be extremely damaging to young magnolias. Copper-Count-N at 1 quart/100 gal water. Algal leaf spot. These pathogenic bacteria inject several proteins and small-molecule toxins to get past host immune mechanisms. Neil Bell, 2019. … 3 photos. For a faster approach, use a water hose to wash the fungus off the surface. Both are treated with the same chemical control and the only one that can be used by the home gardener, signified by an H surrounded by a box: Monterey Liqui-Cop at … The first symptoms include the appearance of thread-like formation on the underside of leaves. These diseases range in severity from minor annoyances to possibly life-threatening conditions. 48-hr reentry. Anthracnose. Verticillium wilt is not present in cool temperatures; the first signs of the fungal disease won’t be visible until the weather warms. In early spring, about 14 days after the flowers have opened, the petals become water-soaked, turn brown, and then black. This blight also stunts growth in new shoots, which can ultimately make the tree look malformed. Junction at 1.5 to 3.5 lb/A. Like many tree diseases, wetwood infects the magnolia tree through open wounds and natural openings. Leaves can be damaged by leaf spot. Sooty mold threatens the life of the magnolia only in rare occasions where the growth covers entire leaves, blocking sunlight needed for photosynthesis. Bacterial blight tends to affect woody plants like trees and shrubs. Dothistroma blight kills needles on evergreen trees. Note that under cultural controls, both diseases can be avoided by good air circulation and keeping the leaves dry. Promoting a healthy growing environment is the best way to prevent your plants from picking up this disease.