Diseases of Ming Aralia

Xanthomonas Leaf Spot

• Xanthomonas leaf spot is caused by a bacterium (Xanthomonas campestris) that can infect Ming aralia. The disease manifests itself as tiny, corky-appearing areas on the lower leaf surface. The lesions often enlarge to 1/8 to 1¼ inches in diameter and become black. Some are surrounded by a bright yellow halo. The bacteria often spread through water splash from leaf to leaf, and on occasion from stem to leaf. The leaf spotting itself is rarely damaging but can indicate a more serious problem. Promptly remove infected leaves and only apply water to the base of the plant. The American Horticultural Society (AHS) recommends spraying the plant with copper bactericide.

Alternaria Leaf Spot

• Fungus in various forms can invade your Ming aralia. Alternaria leaf spot (Alternaria panax) is one such fungal disease. This fungus creates lesions that are tiny and translucent. Later they turn tan with a greenish-yellow halo. Lesions on the Ming aralia enlarge to ½ inch and cause the plant to defoliate within five days of infection. As with other fungal diseases, eliminate overhead watering and exposure to rainfall. Adequate water drainage is critical for preventing all types of fungal diseases. The University of Florida also recommends applying greater than recommended levels of fertilizer.

Anthracnose

• Anthracnose is caused by another invading fungus (Colletotrichum gloeosporioides). The University of Florida describes the lesions as being water-soaked and surrounded by a yellow halo. They eventually turn tan or black with black fruiting bodies appearing on the upper surface of the leaf, usually on the margins or wounded areas. Prevent anthracnose by avoiding overhead watering and exposure to rainfall.

Rhizoctonia Aerial Blight

• Rhizoctonia aerial blight (Rhizoctonia solani) is a soil-borne disease that begins with brown lesions on Ming aralia foliage and spiderweb-like mycelia developing over aerial parts of the plant. Eventually the tan to reddish-brown webbing covers the plant and the tissue quickly wilts and dies. Greenhousemanagementonline.com says that Rhizoctonia can also cause constriction at the base of some plants, causing them to die. The University of Florida recommends putting fungicide into the soil. Planting disease-free plants in sterile soil is the best prevention.

Pythium Root Rot

• The fungus Pythium is both soil- and water-borne, making it more difficult to prevent. Symptoms range from the entire Ming aralia plant wilting and dying to disintegrating roots to stunted growth. The American Horticultural Society says that seedlings are more prone to the disease, but older plants can succumb as well. When a plant gets the disease it is best to start over. The AHS recommends raising seedlings in sterile soil and watering with clean water. If you will be using the same container for the next tree, first wash it with a 10 percent bleach solution.

Fusarium Root Rot

• Fusarium root rot is another threat to Ming aralia. According to the AHS, this fungus blocks the vascular tissue with a gum-like substance either entirely or partially, causing the plant to die. Symptoms in woodier-stemmed plants such as the Ming aralia are wilting and withering of foliage. The AHS also reports that in some plants pink or white fluffy fungal growth may display around the infected area. Remove diseased plants and replace the soil. Don't plant in the same container for at least five years.