Are the leaves spotted or blotched?
Are the flowers covered with gray mold?
Are the leaves covered with white powdery patches?
Do the crowns and roots rot, an unpleasant odor may be present?
Do the leaves have large, ragged holes in them?
Are the leaves pale on their upper side and are there any dusty blisters on the undersides?
Your plants might be suffering from fungal leaf spots. Spots may enlarge rapidly, especially in wet weather. Destroy infected leaves or plants. Spray plants with sulfur to prevent the disease from spreading, especially if the weather is wet. Prevent problems by thinning plants to provide good air circulation.
Likely cause for these symptoms is a fungal disease - Botrytis blight. Other symptoms include brown to black spots that may appear on leaves and petals. You can only prevent Botrytis blight disease by planting sweet alyssums in areas with good air circulation. Water plants sparsely. Infected plants should be removed. Spray weekly with a copper fungicide until the disease is under control.
White, powdery coating on the leaves is caused by a fungal disease Powdery mildew. Powdery mildew usually appears in damp places. Encourage good air circulation around the affected plants by thining any surrounding plants. Water plants from bellow to keep foliage dry. Any affected leaves should be cut off and removed. Any commercial fungicidal spray will protect your plant from further infections.
Balloon flowers can occasionally be infected by fungal and bacterial Crown or Root rot diseases. Crown injury and excess moisture during dormancy also increase the chances of infection. Choose well-drained sites. Add organic matter to improve soil drainage. Keep winter mulch away from crowns. Remove and discard infected plants and the surrounding soil.
Large, ragged holes in the leaves are caused by slugs and snails. Slugs and snails feed on the plant leaves usually at night. To control slugs and snails use diatomaceous earth around your plants. You can also handpick them during the night or use shallow dishes filled with beer as a trap.
Likely cause for these symptoms is a fungal disease - Rust. Provide good air circulation around plants by thining them. Avoid making leaves wet when watering. All infected leaves should be removed. Spray leaves with sulfur early in the season to prevent rust or to treat mild infections.
Balloon flowers don't tolerate cold, soggy soil. It causes the plants to rot at the base or die over the winter. They become more vulnerable to fungal diseases. Add organic matter and sand to lighten soil texture, or remove surviving plants to a better-drained location.
https://gardening.yardener.com/Solving-Balloon-Flower-Problems
Ellis, B. W., Bradley, F. M., & Atthowe, H. (1996). The Organic gardener's handbook of natural insect and disease control: a complete problem-solving guide to keeping your garden & yard healthy without chemicals. Emmaus, Pa.: Rodale Press.
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Sreten null
Hi! I’m Sreten Filipović. I graduated from the Faculty of Agriculture at the University of Belgrade, with a master's degree in Environmental Protection in Agricultural Systems. I’ve worked as a researcher at Finland's Natural Resources Institute (LUKE) on a project aimed at adapting south-western Finland to drought episodes. I founded a consulting agency in the field of environment and agriculture to help farmers who want to implement the principles of sustainability on their farms. I’m also a founding member of the nonprofit organization Ecogenesis from Belgrade whose main goal is non-formal education on the environment and ecology. In my spare time, I like to write blog posts about sustainability, the environment, animal farming, horticulture, and plant protection. I’ve also published several science-fiction short stories.
You can find me on LinkedIn at https://www.linkedin.com/in/sreten-filipovi%C4%87-515aa5158/