Geraniums, members of the genus Pelargonium, are easy to care for, decorative plants commonly used in gardens and window containers. However, these brightly colored flowering plants can suffer from infestations of insects, fungus and numerous diseases.
Geranium plants can fall victim to infestation by several insect pests, such as aphids, caterpillars, mealy bugs, spider mites, thrips and whiteflies. Therefore, you need to inspect plants and leaves regularly for signs of these pests. Additionally, geraniums that are kept indoors are particularly vulnerable to aphids and whiteflies.
Remember to remove dead flowers and leaves from your geraniums because they can promote growth of botrytis, a fungus that attacks young buds and leaves. Botrytis blight is likely to occur during cool, damp weather, and a fungicidal spray can be used preventively to keep geranium plants healthy.
Geraniums can suffer from several diseases, including bacterial leaf spot, black leg, edema, flower break virus, gray mold, mildew and xanthomonas blight. Look for signs of blue or black rotting on the stems, dropping leaves, round spots or dead areas on the leaves, wilting of the leaf edges and loss of luster.