Holly trees are popular landscaping plants because they are easy to grow, adapt to many soil and weather conditions and can be grown across the United States. Holly trees can range in size from small dwarf shrubs to towering trees. In addition, they have red, orange, yellow and even black berries that add texture and color. However, hollies are also susceptible to various fungal diseases. These common diseases can be contracted at the nursery or cultivated through repeat exposure to moisture.
According to University of Arkansas Division of Agriculture, leaf spot is commonly found on Burford, Japanese, American and yaupon Holly. Symptoms appear as tiny yellow spots that get larger and often turn a tan or brown color with a purple-black border. UADA states that defoliation and shoot blight will occur if the infestation is serious. Treat infected Holly trees by cleaning up all fallen leaves around the plant and prune all infected or dead shoots. Fungicides can be applied in the spring to plants that have been damaged by leaf spot.
Anthracnose is a disease that generally affects English, Chinese, inkberry and winterberry holly. The Alabama Cooperative Extension Service states that Anthracnose can be identified by tan and brown leaf blotches. In addition, several pin-sized pink or orange spores can be seen inside of the blotches. The ACES recommends applying a fungicide in late spring. Repeat the application every seven to 14 days as needed, the website states. ACES also states that you can prevent Anthracnose and other common diseases affecting Holly trees by timely surface watering, maintaining recommended soil fertility and pH and choosing an adapted holly cultivar as well as proper plant care.
Black Root Rot
Thielaviopsis black root rot often causes the plant to become stunted once the roots become severely rotted. The Virginia Cooperative Extension states that the disease will also cause holly leaves to lose color and drop. Black root rot is often associated with Japanese, inkberry and blue or Meserve holly. "In established plantings, Japanese hollies that already show foliar symptoms usually have extensive root damage and should be removed," VCE states. A soil drench fungicide may also be applied.
Tar spots cause small yellow spots to appear on the holly's leaves. The yellow spots may turn reddish brown just prior to causing the infected areas to fall and leave a hole in the leaf. Tree Help, a tree disease-related website, states that you can prevent the spread of tar spots by gathering up any fallen leaves from an infected plant and destroying them.