Identifying Diseases in Your Impatiens Plants

Blue diamond impatiens bears an abundance of bright ultramarine blue blooms.

Even colorful and long-lasting impatiens can start to droop or become sickly. What can be done to prevent or cure diseases that may befall them?

TIP: Expert gardener and advisor, Karen Thurber adds, "The best method to avoid disease on your inpatients is to; buy plants from a reliable nursery, plant in fertile well drained soil with partial shade, and use good cultural practices, such as water in the morning."

Spots on Leaves

Brown spots on impatiens leaves, some may even have holes in the leaves, could be a sign of one of several leaf spot diseases that plague impatiens.

Many gardeners find leaf spot to be an annual problem. The best way to control leaf spot is to spray a fungicide every 2 to 3 weeks. Left untreated, more spots will appear, causing the leaves to fall off. Foliage turns yellow and the impatiens plant may even die.

TIP: Karen advises, "When using any pesticide or fungicide, be sure to read and follow all directions on the label."

In addition to spraying with fungicide, pick off the affected leaves. Also, avoid splashing water on impatiens. Water the impatiens plants early in the day so the foliage has sufficient time to dry before the evening. Never leave impatiens in a drowning, wet state come nighttime.

Downy Mildew

Early signs of this disease are flowers wilting, very pale leaves, and a white, purple or beige coating on the underside of the leaf, often covering it completely. Left untreated, this fungal disease causes leaves to eventually yellow and fall off, the plant produces fewer blooms, and it can even die. The spores will quickly spread to surrounding impatiens.

The best solution is to remove infected plants and protect the others with regular fungicide spray application.

Tobacco Mosaic Virus

With this disease, the leaves take on a ring pattern, lines or a mosaic. Other symptoms include curling leaves and plants that become stunted or dwarfed.

There’s only one remedy--removal of all infected plants. There is no fungicide to cure this virus.

Botrytis Blight

Commonly affecting impatiens, botrytis blight is a fungus that attacks the plant’s flowers and buds. It is also called gray mold. Flower buds turn brown and won’t open. Flowers that have already bloomed also turn brown and become covered with a gray growth of fungus. This fungus also appears on the leaves.

To control botrytis blight, remove all infected impatiens leaves and buds. Prune any dead or dying sections. Be careful to get rid of all infected areas of the plant, whether above or below the soil line. Preventive measures include spraying with copper sulfate or Mancozeb fungicides when plants are about 6 inches tall.

TIP: Karen adds, "Root rot can also be a problem in some situations. Lower leaves on the affected plants will wilt, turn yellow and fall off. Improving drainage or lowering water applications will help avoid this problem."

Check with Nursery on How to Control

Other bacterial and fungal diseases and viruses can affect impatiens, and sometimes it’s hard to know exactly which one it may be. Take a sample of the leaf to your local garden nursery expert or county agricultural extension agent. Keep it in a sealed plastic bag so that it won’t contaminate any other plants. The nursery representative or county agent should be able to identify the disease infecting the impatiens and give specific instructions on control and prevention.