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Rose Of Sharon Problems – Dealing With Common Althea Plant Issues

Rose Of Sharon Problems – Dealing With Common Althea Plant Issues


Rose of sharon, or althea shrubs as they are commonly called, are usually low maintenance, reliable bloomers in zones 5-8. In this article, we will discuss common althea plant issues. Continue reading to learn about common rose of sharon pests and diseases.

About Rose of Sharon Pests and Diseases

Both pests and diseases can afflict rose of sharon plants at any given time.

Pests

Rose of sharon shrubs are much loved for their large, prolific, tropical-looking blooms in late summer. Depending on variety, these blooms come in a wide range of color and may be single or double. Besides gardeners, these blooms are attractive to bees, butterflies and hummingbirds. Unfortunately, Japanese beetles are also very attracted to the lovely blooms too. One of the most troubling rose of sharon problems, these pests can cause large holes or leave nothing but skeletonized remains.

Some other common pests of rose of sharon are root knot nematodes and aphids. Systemic insecticides can help prevent many of these pests when applied annually in spring.

Root knot nematode damage may appear as wilting or drying up plants. These nematodes cause knots or galls to form on the underground roots of rose of sharon. The galls disrupt the plant’s ability to take up water or nutrients, causing the aerial parts of the plant to slowly die.

Aphids are a troublesome pest of many plants. Not only do they quickly infest a plant and suck it dry, but they also leave behind a sticky honeydew. Aphid honeydew attracts ants and other insects but also traps fungal spores on their sticky surfaces, leading to fungal infections of plant tissues, specifically sooty mold.

Frogs, toads and ladybugs are excellent allies in keeping insect pest populations under control.

Diseases

Rose of sharon shrubs can be sensitive to drought or waterlogged soil. Yellowing or browning leaves, dropping buds, wilting plants or stunted growth problems with althea oftentimes are caused by improper drainage in the planting site. Rose of sharon shrubs need well-draining soil and regular watering in times of drought. Throughout southern regions, flower bud drop can be a common althea problem when plants are not properly watered.

Leaf spot and leaf rust are other common rose of sharon problems. Leaf spot is a fungal disease caused by the fungi Cercospora spp. Its symptoms include circular spots or lesions on the foliage and premature dropping of leaves. Leaf rust can also cause spotting of foliage; however, with rust, orange-rust colored fungal pustules will form on the undersides of the foliage.

Both these fungal diseases can overwinter in garden debris, soil and on plant tissues, re-infecting plants year after year. To end this cycle, cut back all infected plant tissues and destroy them. Then, in spring, spray plants and the soil around them with preventative fungicides.

Some other, less common, althea plant issues include gray mold, powdery mildew, cotton root rot and cankers.


How to Care for a Rose of Sharon Bush

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Although it doesn't produce the dinner plate-size flowers of some tropical hibiscus, rose of Sharon (Hibiscus syriacus) makes up for that loss with hardiness, easy-care growing requirements and lovely hollyhock-like flowers with delicate, ruffled petals. Given the right care, rose of Sharon can grow up to 12 feet tall and 10 feet wide in U.S. Department of Agriculture plant hardiness zones 5 through 9.,


Freedom Althea Overview

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Freedom Althea Pests / Problems

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Gardenality.com · Gardenality Genius · Zone 8A · 10° to 15° F · Comment About Planting
Freedom Althea, also known as "Rose of Sharon," grows in a wide range of soil types but prefers a well-drained site. For best performance, plant in full to mostly sun. Some shade will be tolerated, but flowering will likely be reduced. As a taller growing variety (up to 12 feet) Freedom Althea is most attractive and useful when grown as a small tree. It can be planted as a single specimen or in groupings anywhere in the sunny landscape.

To plant an Althea, dig a hole no deeper than the root ball and two to three times the width of the root ball and fill it with water. If the hole drains within a few hours, you have good drainage. If the water is still standing 12 hours later, improve the drainage in your bed, perhaps by establishing a raised bed or mound. Turn and break up the soil removed from the planting hole. If the native soil is dense, compacted or heavy clay, mix in a good organic compost or soil amendment at a 30/70 ratio with the soil removed from the hole. Remove your plant from its container and carefully but firmly loosen the roots around the exterior of the root ball. Set the plant in the hole you've prepared, making sure the top of the root ball is slightly above the soil level to allow for settling. Pull your backfill soil mixture around the root ball in the hole, tamping as you go to remove air pockets. Then water thoroughly and cover with a one to two-inch layer of mulch.


Powdery Mildew

Though it causes very little damage to most plants, powdery mildew is an unsightly fungal disease that affects Rose of Sharon bushes. It appears as grayish or white spots on the leaves, stems buds and flowers. It can cause leaves to curl and drop and cause buds to become deformed. The fungus overwinters in plant tissue and releases spores in the spring. Most often it can be left untreated. If the disease returns year after year, it may need to be treated by moving plants to a sunny, dry location and removing all dead debris from around the plant. Treat with a fungicide at the first sighting of spots in the spring to be effective.

  • Though it causes very little damage to most plants, powdery mildew is an unsightly fungal disease that affects Rose of Sharon bushes.
  • If the disease returns year after year, it may need to be treated by moving plants to a sunny, dry location and removing all dead debris from around the plant.