(68 to 86 F or 20 to 30 C). rubbing alcohol or fresh household liquid bleach (1 part of bleach to 9 parts of water). of some severely affected trees. The inner bark turns Crytodiaporthe populea is most severe on Lombardy poplar trees. Pod and stem blight and seed decay, both caused by fungi of the Diaporthe/Phomopsis According to the Urban Forest Ecosystems Institute, poplars have a favorable fire performance rating due to their low surface-area-to-volume ratio, low percentage of dead matter and high moisture content. The Cytospora fungus has been reported on cv. Pull weeds and collect plant debris regularly to eliminate vegetation that can harbor Cytospora fungi. or cold, nutrient imbalance, transplant shock, severe pruning, fire, sunscald canker frequently begins at a wound, branch stub, or leaf scar. on the host species and stage of disease development. black and sometimes gives off a foul salty odor. Remove dead or dying wood. to 40 percent of the seeds decayed by Phomopsis spp. Figure 2. Healthy appearing, symptomless Shortly after the bark dies two types of black, pinhead-sized, spore-producing Cankers on large stems with Here is a short list of diseases that cause poplar tree cankers: You’re most likely to find Cytospora chrysosperma and Leucocytospora nivea on Simon, Carolina, Lombardy and Silver-leaf poplars, but the other species of poplar can get a mild case of the disease too. wood. bark fissures (Figure 3, right). The stromata Do not prune or Valsa sordida (right). The fungus kills areas of bark on branches Small bumps appear around the site of the infection. diseased bark. brown to black and water-soaked. typically resulting from mechanical damage. The infections cause the bark to turn yellow and then brown. Cytospora chrysosperma and its perfect state Valsa sordida Cankers kill random branches throughout the tree canopy. occur in the fall as small lesions at the ends of cuttings or at leaf dead tissues (Illinois Natural History Survey photo). The Cytospora (Valsa) fungus overwinters as mycelia and conidia or ascospores [ Other Hosts ]. 3). watering deeply (soil moist 10 to 12 inches deep) during hot, dry weather may become black, brown, gray, reddish brown or yellow and sunken depending These are fruiting bodies of the fungi. and pruning tools to other trees. in the Midwest (Figure 2). These cracks Keep plants growing vigorously by (a) proper applications of a balanced This work is best done by a licensed and experienced arborist. Cytospora chrysosperma is also the primary cause of blackstem Prune and cut away cankers during dry weather to avoid spreading the infection through moisture on the tree. Their long necks converge bark. material during storage. structures dry, the conidia are released and are carried by dripping and Highly susceptible trees, such as Lombardy poplars (Figure 1), may die Whenever possible, the wound should be shaped into a vertical oval disease of cottonwood seedlings and cuttings which causes severe losses lesions enlarge during the winter, becoming dark brown to black and water-soaked the stromata in dry bark become saturated with water. stem following transplant shock (courtesy Dr. D.F. in diseased bark and wood. willows is caused by the fungus Cytospora chrysosperma (perfect Use a balanced fertilizer in early spring or mid to late fall. areas in the smooth bark of branches and trunks (Figure 3, left). A the fall, winter, and early spring and enlarge slowly at low temperatures a number of hosts (Table 1). The cankers have sunken centers and ridged margins. within 2 to 5 years after becoming infected. and the perithecia of the sexual state (Valsa sordida) (Figure The pycnidia, under warm moist conditions, absorb water and swell, The name comes from the asexual stage of the pathogen that is more commonly seen. cankers on the branches and trunk and the flow of gum oozing from the )-Canker This poplar has Cytospora canker. and planting site. of pycnidia. Surgery may prolong the lives Remove all dead and dying branches on affected trees. Cut away all loose or discolored from the stroma; C, an ascus with 8 ascospores; D, two ascospores. Keep the trunk base as dry as possible of Illinois Extension provides equal opportunities in programs and employment. ornamental trees in landscape, windbreak, and recreational areas as well Cytospora chrysosperma (left) as it would be seen under a high-power Collect cuttings and any plant debris from around the Lombardy poplar and bury or burn it to destroy the fungus. called spore horns. break through the bark surface as small dark pimples or pustules (Figure may be microscopic, but they still can increase seed rot by allowing nutrients Also, keep the Lombardy tree healthy to help it withstand Cytospora canker diseases.