Bare Spots on a Japanese Honeysuckle Vine

Causes

• Insolibasidium deformans, a fungus, is responsible for leaf death and bare spots on Japanese honeysuckle. The fungus reproduces via spores, which overwinter near the bottom of the vine. Once temperatures and humidity increase, the spores release mycelium -- tendrils that grow and develop mature forms of the fungus. The maturing fungus causes leaves to take on a yellow appearance. The yellow leaves will soon curl, turn brown and prematurely fall from the vine.

Prevention

• Japanese honeysuckle is considered resistant to leaf blight, but this label should not be taken with great seriousness. When grown in overcrowded, moist and warm conditions, even the most resistant strains can succumb to leaf blight. The problem is found in nurseries and other environments that have diminished circulation. Prevent fungal growth by planting vines 36 to 60 inches apart. Thin out crowded areas. Avoid overhead watering, especially in areas where average humidity is close to 100 percent. Japanese honeysuckle that shows signs of fungal infestation and leaf drop should be treated with fungicides. Follow the manufacturer's recommendations involving dosage amounts and timing of the application.

Defoliation

• If the honeysuckle does not show signs of fungal infection, investigate possible cultural causes of defoliation. Japanese honeysuckle grows well in a range of soils -- from clay to loam. It does not do well in areas with full sun. Healthy Japanese honeysuckle is grown in areas of dappled light or in areas that receive less than six hours of direct sun each day. It is a moisture-loving plant, so ensure that it receives enough water. Surrounding soil should be moist to a depth of 2 inches. When left dry, the plants can experience defoliation.

Considerations

• Avoid planting Japanese honeysuckle freely in a garden. The plant grows rapidly and can overgrow flower beds and native plants if left unattended. It is capable of smothering other plants. Instead, grow Japanese honeysuckle in containers. Containerized honeysuckle can be trained to climb trellises or railings. When growth is controlled, it is less likely for fungus to find moist areas with poor air circulation. This leads to healthier vines and plants.