Honeysuckle is a fragrant addition to many gardens and yards. While this plant is beautiful and aromatic, it is susceptible to a foliage disease that is caused by fungi and helps mildew to develop on host plants. Powdery mildew often infects honeysuckle, and if severe, it can cause an unsightly mess on the plant.
Powdery mildew is caused by host-specific fungi, meaning that different types of fungi infect different host plants. However, all powdery mildew fungi cause symptoms that are strikingly similar, no matter the host. Almost all plants are affected by some type of powdery mildew fungi. Warm days and cool nights promote the development of this disease. High humidity is also necessary for infection of honeysuckle. However, powdery mildew fungi is different from many types of fungi because it does not require moisture on the plant leaves to germinate.
Powdery mildew causes a white coating of fungus to develop on the leaves, stems and flowers of honeysuckle. This coating is similar to icing sugar or talcum powder and is easily rubbed from the plant, however, it soon returns. While honeysuckle with powdery mildew rarely die from the infection, it causes honeysuckle to become unsightly and unattractive. Honeysuckle with powdery mildew often wilt more easily than healthy plants and suffer from reduced vigour.
Powdery mildew fungi thrive in humid areas, therefore, it is important to avoid planting honeysuckle in shady areas or too close together. Avoid watering your honeysuckle late in the day, as your plant needs time to dry completely before nightfall. While powdery mildew fungi do not require moisture to infect plants, excess moisture may encourage other foliage disease to develop. Avoid applications of fertilisers with high contents of nitrogen, as this promotes new growth which is a favourite of powdery mildew fungi. Remove all infected leaves and plant tissue from your plant and destroy it to reduce the spread of disease.
Severe powdery mildew may require fungicide applications along with cultural control methods. Fungicide applications are most effective on honeysuckle when symptoms appear in the spring or summer. Avoid the use of fungicides when infection begins in the late summer or early fall.