Are the leaves yellowing, wilting and, dying?
Are the leaves pale on their upper side and are there any dusty blisters on the undersides?
Are the leaves curled and distorted?
Are the leaves covered in coarse stippling and may appear silvery?
Are the stems flopping over?
Yellow leaves that wilt and die usually indicate Root rot. Several pathogens cause root rots of seedlings as well as mature plants. Poorly drained, overly wet soil promotes rot so choose well-drained sites and add organic matter to improve drainage. Remove and destroy infected plants. Solarize the soil before replanting.
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.
Distorted and curled leaves are caused by aphids. These tiny insects cluster under leaves and on growing tips where they feed on plant sap. Leaves, stems, and buds get distorted and later leaves and flowers drop from the plant. You can control them by washing them off the plant with water spray. Insecticidal soap should be used with severe infestations.
These symptoms may indicate thrips. Thrips are tiny, yellow to black flying insects. Severely infected plant parts should be removed and destroyed. Control thrips by introducing lady beetles or lacewings, their natural predators. Insecticidal soap helps in severe infestations.
If the flower spikes are not removed Amsonia stems often will flop over. This will also happen if the plants are in too much shade. Remove flower spikes if you haven't and if your plants are growing in the shade move them in a sunnier place.
Poor growing conditions may have caused a sickly look of your Amsonia. Ideal Amsonia growing conditions call for a humus-rich soil and a thick layer of organic mulch. In soils that are constantly moist, Amsonia prefers full sun. Otherwise, plant it in light to partial shade.
https://www.burpee.com/gardenadvicecenter/encyclopedia/perennials/learn-about-amsonia/encyclopedia__amsonia-article.html
https://www.gardeningknowhow.com/ornamental/flowers/amsonia/growing-amsonia-plants.htm
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/
