Honeysuckle (Lonicera spp.) is a hardy plant that is generally healthy. One of the most common diseases to damage the honeysuckle plant is leaf blight. This fungal disease can cause a mould or a fungus to appear on the leaves of the plant, especially in lower branches where there is less air circulation to dry the leaves.
Honeysuckle is a shrub used as a windbreak shrub throughout the United Kingdom. This plant matures to a height of 1.8 to 4.5 m (6 to 15 feet). This plant is considered invasive and is capable of spreading through seeds dispersed by natural wildlife such as birds. Honeysuckle plants yield white flowers in the spring that emit a pleasant fragrance.
Leaf blight on honeysuckle plants is caused by the Insolibasidium deformans fungus. This disease can cause damage to the appearance of the plant but it is rare that the disease progresses to the point that the life of the plant is threatened.
Leaf blight can cause the leaves of the honeysuckle plant to crinkle and roll onto themselves. As this disease progresses, leaves turn yellow or brown and drop prematurely. Infected leaves frequently have lesions surrounded by what looks like yellow or white mould.
Fungus grows rapidly in especially moist weather conditions and temperatures between 15.0 and 17.7 degrees C (59 and 64 degrees F). As the fungus grows, it produces white spores that spread the disease to other parts of the same plant or to new plants entirely. These spores can be spread through irrigation, by animals or by wind. The spores that the fungus produces in the fall are capable of surviving the winter on leaf surfaces and in the soil. As the temperatures in the spring warm up, these spores can infect the following season's growth.
Controlling leaf blight
Diseased plants should be pruned of any infected leaves or stems. Removed portions of the plant should be discarded and the shears used for pruning should be sterilised between cuts to prevent the fungal spores from travelling from one area to another. Any leaves that have fallen to the ground should be removed and disposed of promptly to help control the disease. Annual pruning of the plant can also increase air circulation and help prevent the growth of fungus because lower leaves wouldn't stay as moist after rainfall or watering. The application of the chemical mancozeb in the spring can also be effective in preventing the disease.