![]() Symptoms Often Confused with Boxwood Blight Residential properties that have tested positive for boxwood blight are strongly encouraged to select alternatives to Buxus species when replanting. Do not dispose of the plant until instructed. Visit the Penn State Plant Disease Clinic website to learn more about collecting and sending plant samples. If you are a licensed nursery or nursery dealer, you may also contact your Pennsylvania Department of Agriculture regional office for assistance. If you suspect a boxwood is diseased, collect a sample, double bag it, and take it to your local Penn State Extension office. It is very important that suspected occurrences of boxwood blight are confirmed. So I Think I Have or See Boxwood Blight, What Should I Do? This allows for early detection and helps increase the probability of successful eradication. Proper quarantine procedures for new shipments of boxwoods and a rigorous inspection routine should be implemented. To learn more about tolerant Buxus species and fungicides available, visit the AmericanHort Knowledge Center Boxwood Blight page. sempervirens plants have been found to be extremely susceptible to boxwood blight, particularly the varieties 'Suffruticosa' (English) and 'American'. Current research is looking into the survival of the fungus through composting at this time, composting infected boxwoods is not recommended.īuxus species show a wide range of susceptibility to boxwood blight. Do not chip boxwood-blight-infected boxwood cuttings for use in mulch, as the disease may spread this way as well. The transport of infected boxwood leaves or stems attached to clothes, shoes, or equipment can also lead to the spread of this disease. Infested tools can spread the infection from location to location rapidly. Proper sanitation is the best management strategy for boxwood blight. White fungal structures on the undersides of affected leaves Management Leaf spots (top) coalesce to form lesions (bottom).īlack streaks present on the branches and twigs. Sending a sample to a diagnostic laboratory is the only way to be sure. Other conditions can mimic signs and symptoms of boxwood blight. ![]() Signs of the disease are the presence of white fungal structures mainly on the underside of the leaf, as well as on diseased parts of the stem. Characteristic black streaks can also be present on the twigs. The spots can then merge, forming lesions that take up a large portion of the leaf and lead to the death and dropping of the leaf. Over time the spots will grow, and a concentric ring pattern will develop. New infection begins in mid- to late summer as dark circular spots on the newest foliage. The symptoms for boxwood blight are very well defined. US states with confirmed boxwood blight presence (Rob Harvey 2014) Symptoms The production of hardened survival structures, called microsclerotia, allow the fungus to survive harsh conditions. Other plants in the Buxaceae family may serve as hosts as well. All boxwood cultivars, as well as Pachysandra and Sarcococca plant species, show some degree of susceptibility. Long-distance dispersal is the result of human plant movement. Rain, irrigation water, and contaminated equipment and workers all can quickly spread the pathogen from plant to plant. The spores can then be deposited on a healthy plant and cause infection. These spores are extremely sticky and will cling to any dog, bird, insect, or person brushing past. ![]() Within a week the pathogen can produce spores again. Spores can initiate infection very rapidly under humid/wet conditions. Boxwood blight is caused by the fungus Calonectria pseudonaviculata (otherwise know as Cylindrocladium pseudonaviculatum and Cylindrocladium buxicola).
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