English ivy (Hedera helix L.) is a perennial vine that is desirable for its ability to grow in full shade and for its attractive, glossy evergreen leaves, which can range in color depending on the variety. The plant is a prolific climber and spreads rapidly. English ivy can quickly overtake and cover trees and other desirable plants. For that reason, it is considered an invasive weed in many states. English ivy can suffer from a number of disease, most of them fungal.
Xanthomonas Leaf Spot
Xanthomonas leaf spot, like all leaf spot diseases, is caused by a water-borne fungus. The disease usually infects English ivy during warm, wet springs. The main symptom is the appearance of dark brown or black spots on the leaves. The spots are asymmetrical and may have lighter-colored borders. In some cases, the spots will drop out of the leaves, leaving them with a ragged appearance. This disease can affect the growth of new leaves as well, leaving them malformed. The best way to prevent leaf spot is to drip-irrigate the ivy so that it is not exposed to splashing water. Covering English ivy to protect it from rain also helps. Remove any affected leaves as soon as you notice them, and prune away infected sections of the plant. If the entire plant is infected, spray it with an application of cupric hydroxide according to the directions on the package.
This disease is caused by the fungus Botrytis cinerea, which can spread rapidly if the weather is hot and humid. The primary symptom is brown or tan lesions on the foliage of the English ivy. As the infection progresses, the lesions will develop a "fuzzy" appearance, which is caused by the development of fungal spores. In a rainstorm, the spores will release and travel on the water to land on other leaves, infecting them as well. Bortrytis blight thrives in humid conditions. Plant English ivy in a location where it will be exposed to plenty of air, wind and sunlight to dry it out. If the plant becomes infected, treat it with a fungicide containing vinclozolin or iprodione.
Phytophthora Root Rot
Phytophthora root rot is caused by a fungus that lives in the soil. Unlike the fungi that cause leaf spot, this fungus can sit unactivated in the soil for years before infecting the English ivy. Phytophthora palmivora can even be present in potting soil. This fungus attacks and destroys the roots of the plant, causing the ivy to wilt, discolor and eventually die. Heavily infected plants should be removed and destroyed. Sterile potting soil should be used for container plantings of English ivy to prevent the chance of root rot. If the plant shows symptoms of root rot, fungicides containing ethazol, metalaxyl or ethazol-thiophanate-methyl can be used to try to save the ivy.
Anthracnose can devastate English ivy, according to Jackie Mullen, a master gardener at the University of Arkansas. The disease is most commonly caused by the fungus colletotrichum trichellum and can manifest in any number of ways, including fungal leaf spots, deformed growth, irregular spots of dried leaf tissue and tiny black spots on the leaves. The spores of the fungus are spread by splashing water (rain) or on the bodies of insects. Antracnose can only be prevented, not treated. Use a preventative fungicide labeled for athracnose prevention each spring according to the directions on the package. Infected plants should be carefully removed and disposed of in plastic bags, not thrown onto a compost pile as this could spread the disease.