Honeysuckle plants are sweet-smelling plants that grow as shrubs or vines. There are 180 different species. While their scents are enjoyed by many and favoured by bees, honeysuckle plants can also be subject to infections and diseases. Caring for honeysuckle plants includes controlling powdery mildew, sooty mould, crown gall, and leaf scorch.
Found mostly in high-humidity environments, powdery mildew is a grey coating over the honeysuckle leaves. It starts off as white, nondescript dust that mixes in with regular dust. However, it can begin to matt and form large, white patches full of spores. Powdery mildew can cause yellowing of the leaves and distort the shapes of buds and growing tips. The honeysuckle plant may look weak overall due to the powdery mildew robbing it of nutrients. It can be controlled indoors by removing any dead or dying leaves and controlling humidity. Outdoor care requires fungicide applications.
Sooty mould looks like a black coating on the honeysuckle plant, usually on the fruit or branches. Although not always deadly, sooty mould continues to grow off of honeydew left behind by insects. You can remove the sooty mould by washing it off the honeysuckle plant, but the best method of sooty-mould control is to control the insects.
Crown Gall attacks the honeysuckle plants by first entering any damaged roots or lower stem wounds via the soil. Crown gall plasmid binds with the honeysuckle's DNA and begins to corrupt the cells, causing tumour-like swellings that appear white, rounded, and soft. The tumours eventually become brown and corky. When the galls swell in size on the stem, they cut off both water and nutrient supplies to the rest of the plant. Controlling crown gall can't be done with regular fungicides. The best method is to have a healthy growing environment and clean propagation, i.e., not leaving open wounds on pruned honeysuckle plants. Galltroll, a biological application, can help prevent the spread of the disease.
Leaf scorch makes the honeysuckle plant leaves look discoloured along the insides and on the leaf veins. Tissues tend to be yellowish or dark. Leaves may even turn completely brown in colour and wither. Leaf scorch is caused by insufficient nutrients, low-quality or compacted soil, and periods of drought. Control leaf scorch on honeysuckle by applying a copper-based fungicide upon first appearance, or by removing withered leaves entirely to prevent it spreading.