Do the leaves have spots or blotches?
Are there any rust-colored spots on foliage?
Is there a white, sticky froth covering the insect eggs on twigs?
Your plant is suffering from a fungal leaf spot. These can come from a number of fungus diseases, causing spots to occur on foliage. 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. Spray between rains. Prevent problems by thinning plants to provide good air circulation.
Rust-colored spots on foliage indicate 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.
Treehoppers lay eggs under the bark of twigs. The insect itself is not seen but the white, sticky froth covering the eggs is quite noticeable. The insect is seldom serious. Use Horticultural Oil in a dormant spray dosage to control treehoppers. Horticultural Oil should be applied when the temperatures are between 35 and 85 degrees Fahrenheit.
Mineral deficiencies can cause tip chlorosis or necrosis or cause foliage to discolor, fade, distort, or become spotted, sometimes in a characteristic pattern that can be recognized to identify the cause. Nutrient deficiencies rarely occur in most woody landscape plants. When they do occur, nitrogen and iron are the most commonly seen deficiencies. Apply only the mineral found to be deficient.
https://www.mortonarb.org/trees-plants/tree-plant-descriptions/wafer-ash
E. F. Gilman, D. G. Watson, Ptelea trifoliata - Common Hoptree, Forest Service, Department of Agriculture
Wilen, C., Dimson, M., Plant and Pest Guide - Los Angeles State Historic Park, The University of California, Division of Agriculture and Natural Resources
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.
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/
