My Chrysanthemums Are Dying

Chrysanthemums (Chrysanthemum spp.), also called mums, come in hundreds of different varieties, each offering flowers in colors of crimson, yellow, gold and pink. Chrysanthemums cannot tolerate excessive moisture as this makes them susceptible to fungal diseases that may result in dying mums. If you notice your mums wilting, turning brown or simply not growing at all, check for the presence of a fungus or virus. These flowers grow in U.S. Department of Agriculture plant hardiness zones 3 to 9, depending on the species and variety.

Fungal infections, such as bud rot, verticillium wilt and mildew, commonly afflict chrysanthemums. Symptoms show up on the plant's leaves. Rusted leaves develop brown spots under the leaves, and later the leaves die. To control rust, apply sulfur to the plant. Avoid spraying the flowers, and using sulfur during very hot weather.

If the mums suffer from mildew, white and gray fuzzy spots will appear on leaves. Sulfur also helps control mildew. If the mums are turning brown or red, the plant may suffer from Septoria leaf spot. Infected leaves also bear black spots. Bud rot infects the mum's unopened buds, causing them to stay closed.

Treat both problems with a Bordeaux mixture fungicide that contains copper sulfate and lime. Keep in mind that the copper can cause discoloration, so take care when spraying that it doesn't get on any painted surfaces.

Chrysanthemums that wilt or stop growing and producing flowers may suffer from verticillium wilt. Verticillium also turns leaf veins yellow. This soil-dwelling fungus is difficult to remove completely. Fungicide has little effect once verticillium has infected the mum. Pull up any infected mums and burn them to prevent spreading the disease. Do not put any new mums in the infected soil. The new mums will become infected, as well.

Several diseases cause mums to look stunted. One viral disease, aster yellows, transmits to mums via an insect called the leafhopper. Infected mums grow weak shoots and small flowers. Another viral disease, chrysanthemum stunt, causes leaves to fade. If you touch an infected part of the plant, it is possible to transmit the disease to other plants. For both these diseases, it is best to remove and dispose of the infected plant as quickly as possible.

Leaf nematodes also cause stunted mums. These microscopic worms slowly eat away at the mum's leaves. Look for brown patches between leaf veins and undeveloped flower buds. Mulch around mums to prevent nematodes from moving onto plants from the soil.

Diseases are hard to stop once they start, but proper care all season long should keep your mums healthy. Fungicides and disease-prevention sprays ward off many problems. Apply them every week when it rains heavily to ward off developing fungus.

Give mums room to breathe by planting them in open areas. Keep the leaves as dry as possible when you water. It is best to water mums in the early morning so they have time to dry or use drip irrigation at the soil level.