Diseases Of Goldenrod

Types of Diseases

• Bacterial, viral and fungal maladies can affect goldenrod. One of the viruses that can infect the goldenrod is the tomato-spotted wilt virus. Tiny, winged insects called western flower thrips spread this virus by hatching on the goldenrod and consuming it. Bacterial leaf spot, caused by the pathogen Xanthomonas sp., most often affects goldenrod plants growing under very hot, humid conditions. Some common types of fungal diseases include powdery mildew and rust. Powdery mildew derives its name from the powdery appearance of the fungi. The pathogens Uromyces, Coleosporium and Puccinia often cause rust diseases on goldenrod.

Symptoms of Disease

• The symptoms of goldenrod diseases vary widely, depending on the specific infection. Often, the leaves become discolored. Powdery mildew has a white or gray appearance, while rust diseases cause small brown, orange or yellow spots on a leaf's underside. Rust diseases may also discolor the stems. The tomato-spotted wilt virus causes a mottled, yellow appearance, but it may also cause the leaves to form yellow or brown rings.

Treatment

• After identifying the specific disease affecting the goldenrod, select an appropriate insecticide to treat it. Fungal infections like powdery mildew respond to thiophanate methyl and polyoxin. Non-insecticidal treatments for powdery mildew include neem oil, petroleum oil and jajoba oil. You can also treat rust diseases with thiophanate methyl. Use an insecticide labeled for thrips control for goldenrod affected by the tomato-spotted wilt virus. These include carbamate and pyrethroid insecticides.

Management and Prevention

• If the disease has spread to much of the goldenrod plant, applying an insecticide may not work well enough. In these cases, remove the diseased plant and dispose of it far away from the garden so that the spores do not spread. Goldenrod that is infected with bacterial diseases will benefit from pruning the affected leaves, as long as the disease doesn't affect the entire plant. Many goldenrod diseases are preventable. Water the plants early in the day at the roots; avoid overhead watering. Ensure that there is enough space between the plants to allow for air circulation.