![]() During wet weather in the spring, the bacterium spreads to new growth by wind, splashing rain, insect vectors, or on pruning tools. On lilacs it develops during mild, moist weather. Disease cycle of lilac bacterial blight The bacterium Pseudomonas syringae can overwinter in plant debris, healthy tissue, diseased cankers, perennial weeds, and soil. The bacteria can be found on old cankers, healthy buds, weeds, leaf surfaces and even soil, and is spread by rain, wind, tools, insects and infected plant material. It can also attack weakened or injured plants, such as those affected by frost damage, improper nutrition, inadequate pH, wounds, inappropriate pruning or budding, or other disease organisms. Pseudomonas overwinters on diseased twigs or on healthy tissue as an epiphyte. Lesions may expand and coalesce into larger brown areas. Infected buds may die and never open in spring. Bacterial blight is a common garden ailment caused by a bacterium called Pseudomonas syringae pv. DAMAGE/SYMPTOMS In spring, small, water-soaked lesions appear on the leaves. Flowers can also be infected, first wilting then turning black. These spots may join together and the leaf may crinkle at the edge or along its mid-vein. Young leaves turn black rapidly at the leaf margin and progress down to the petiole until the entire leaf dies. Bacterial blight The bacteria Pseudomonas syringae causes early shoot and branch dieback, distorted leaves, and leaf spots that start out olive green but soon develop water-soaked areas. Actually known to scientists by the complete name of 'lilac bacterial blight,' this disease is caused by the bacterium Pseudomonas syringae pv. On mature tissue, the leaf spots will enlarge along the stem, causing leaf death only around the infected area. A cool, wet, rainy, spring season favors development of lilac blight, especially if rains follow a late frost or winter injury, according to Oregon State University Extension plant pathologists. ![]() It’s a serious disease that affects many plants, including several Asian lilac varieties along with other large fruit and nut tree species. On young tissue, the disease will spread around the stem and girdle it, causing the stem to bend over and die. Bacterial blight is a common garden ailment caused by a bacterium called Pseudomonas syringae pv. As a result of the fungi clogging the branch’s vascular system and preventing the transfer of water and nutrients, individual branches turn brown and die quickly. For a plant with this fungus infection, there is no cure. Initial symptoms include brown spots on stems and leaves of young shoots in early spring, usually surrounded by a yellow border or "halo." As these leaf spots continue to expand during moist conditions, the leaf tissue turns black. syringae, the bacterium that also causes bacterial blight of pear, blueberry, cherry, maple, and many other woody plants. Verticillium dahliae and Verticillium albo-atrum are the two fungi that cause it. syringae or bacterial blight is a common disease affecting not only lilacs, but also other woody plants such as blueberry bushes and cherry, maple and pear trees.
0 Comments
Leave a Reply. |