Ornamental & Tree Diseases
Leaf Spots on Ivy
Ivy, a woody evergreen vine or climbing shrub, is widely used in Mississippi for wall and ground cover and as a house plant. Leaf spots, caused by bacteria and fungi, are the most common diseases which occur on ivy.
Bacterial leaf spot and stem canker are more prevalent on English ivy. At first, the spots are at light green and have a water-soaked appearance. Later they turn brown or black, and tend to have a reddish-brown margin.
When leaf stalks are attacked, they become black and shriveled. The bacteria often move down these diseased leaf stalks and infect the main stem causing die-back of major branches. Under moist, warm conditions, a bacterial ooze may be present on the stems.
The organism causing the disease may enter through wounds or natural openings. Secondary organisms frequently may move in behind the bacterial disease and cause further decay.
The most common fungus leaf spot of ivy is caused by Amerosporium sp. The fungus produces large tan to brown spots on the leaves. Black fruiting bodies of the fungus may form in the dead tissue, giving the spot a speckled appearance. The spots may enlarge and cover most of the leaf surface.
To control leaf spots on ivy, keep the foliage as dry as possible. When watering is required, it's best to do so early enough to allow the foliage to dry during the day. If the infection is light and only a few leaves are spotted, pick these leaves from the plant and destroy them. In the fall, remove and destroy all diseased plant parts. For bacterial leafspot use a copper-based fungicide such as Bordeaux mixture. For the fungus leafspot use a formulation of mancozeb. Repeat the spray applications again in the spring when new growth appears.