Barberries (Berberis spp.) Have a host of excellent qualities. Many feature attractive autumn foliage or berries, and some have thorns that deter hungry wildlife, which means they create excellent hedge crops. In addition, many barberry species and cultivars are hardy and require little maintenance. This does not mean the plants are free of diseases, nevertheless. Barberries may suffer with a number of different kinds of fungi.
Symptoms
Barberries experiencing fungal diseases may exhibit a broad array of symptoms. The fungus may look like a thin, white powder that spots or covers the leaves or as dark, brownish or tan spots. Fungi may also soften the wood of barberry bushes. If a fungus encircles a twig, it might cut off nutrients to that component of the plant. Consequently, the tip of the twig may turn black, shrivel up or stop growing.
Forms
Anthracnose and powdery mildew are the two most common types of fungal infections on barberry plants. Powdery mildew looks like it sounds — like a white powder covering the plant. Anthracnose causes dark spots to appear on the leaves. Both are caused by a several different kinds of fungi. It is important to note that a bacterial infection may also cause dark spots to appear on the leaves of barberries. If the spots appear greasy or wet, they are likely caused by a bacteria, and fungicides will not have any influence on the issue.
Causes
The various fungi that cause anthracnose thrive in cool, wet weather. The spores traveling on spring rain and are blown about by the end. The spores may overwinter in swollen growths called cankers on infected plants. In contrast, the fungi that cause powdery mildew thrive in dry, warm conditions. In fact, powdery mildew development will be stifled if spring weather is extraordinarily wet.
Prevention and Treatment
The fungi that cause anthracnose and powdery mildew have trouble growing when exposed to lots of sunlight and fresh air. Make sure different plants are not shading and overcrowding your barberries, which will make the issue worse. Prune away any naturally diseased branches to prevent the spores from spreading to other parts of the plant, and remove diseased leaves that have fallen from the plant. If you have had fungal issues previously, spray on your barberries with a fungicide in the spring, when the leaves begin to uncurl. Use a fungicide that comprises thiophanate-methyl for anthracnose, and one that comprises myclobutanil, triadimefon or lime sulfur for powdery mildew. Follow the directions on the package as per the size and age of all the plants. Repeated applications may be necessary.