My Asters Are Dying

Asters often come in shades of blue, purple, pink or red.


Asters (Aster spp.) make up a group of more than 600 species and cultivars that are perhaps best known for their colorful fall blooms. Most grow in U.S. Department of Agriculture plant hardiness zones 4 through 8, although some do well in warmer climates. Most asters tend to be resilient and aren't prone to many diseases or pests. A few pests or problems may kill your asters, or make the plants look like they're dying.

Soil Problems

Although asters tolerate many soil types, they do best in drier conditions. Soil that's too wet will quickly cause root rot and, when left unchecked, will kill the plant starting with soggy, wilting leaves. Sandy soil is another mistake as it doesn't hold enough moisture. Both of these mistakes will cause the plants to wilt and eventually die. These fall bloomers prefer a loamy soil that will soak the roots at watering time but not much longer. Transplant the asters to an area with a humus-rich soil, if necessary.

Fungal Diseases

Powdery mildew is the biggest threat to asters and produces white, powdery growth on the leaves. The powdery growth spreads and the leaves and stems begin to wilt and the plant soon shows more symptoms of dying. Fusarium wilt causes the asters to yellow, wilt, turn brown and then die. Older leaves generally die first. Botrytis blight can cause asters to become spotted, leaves will wilt and decay, and twigs may die back; flowers of affected plants may fail to open. Thinning out your plants and watering in the morning at the base can help prevent fungal diseases from spreading. Spraying a ready-to-use fungicide every seven to 10 days -- or as recommended -- can also kill the fungus.

Bacterial and Viral Problems

While fungal diseases are more problematic for asters, bacterial and viral problems aren't unheard of. Fasciation doesn't kill plants, but can cause such a distorted growth that you may think your asters are dying. Invertebrate pests are often responsible for transferring viruses to plants. Aphids, lace bugs, thrips and mites are among the most common culprits. Remove and destroy virus-infected plants or those with fasciation to prevent the disease from spreading to the rest of your asters and ornamental plants.


Many true bugs attack asters but the chrysanthemum lace bug is the biggest threat. This small pest sucks the sap from the underside of the leaves. The leaves yellow and then turn brown and fall off. Other invertebrate pests that attack and can harm asters include aphids, thrips, scale insects and mites. As the pests suck the sap, asters will begin showing discoloration on the leaves, followed by wilting, bloom problems and then death in severe cases. Monitoring your asters throughout the year can help alert you to the presence of these pests. Prune off heavily infested stems to prevent spreading and avoid chemical insecticides because natural predators -- ladybugs, lacewings and spiders -- generally keep these pests in check.

About the Author

Jasey Kelly


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