Heuchera, commonly known as coral bells, is a radiant floral beauty with one of the showiest displays of foliage available in a perennial. Heuchera, however, is plagued by various health ailments that can threaten its hardiness. Brush up on common heuchera diseases so that you can treat them.
Bacterial Leaf Spot
Two main categories of bacterial leaf spot can affect heuchera. Each has different symptoms, but prevention measures and treatment are the same. Pseudomonas is identified by a distorted leaf with red-brown spots. Xanthomonas displays in various irregular or circular-shaped, yellow-rimmed, brown spots. In order for bacteria to enter a plant, an infection must already be in progress through an injury such as a stem breakage or leaf cut. In some cases, bacteria enter through natural openings.
Fungicides will not work on this bacterial disease. Prevention is the best course. Never work among plants that are wet with dew or that have just been watered. Disease spreads more easily through damaged foliage, caused when the stems and leaves have been crushed from handling. Cut back infected plants and dispose of the material carefully. Bacteria will lie dormant in plants even over winter.
Although this disease will most likely not kill your heuchera, it may weaken it to the point where you will see reduced flower blooms in the following season. Anthracnose will appear first as small brown spots that may become larger, merge and perhaps overtake the entire leaf. This stubborn disease loves moisture and poor air circulation, and its spores will survive even in dead material. If a fungicide doesn't help, cut back infected areas. Dispose of diseased material away from other plants and from wind, which can spread the spores. To prevent anthracnose, plant heuchera in full sun with good circulation between plants and avoid over-watering.
Botrytis, or grey mould, can have a grey, fuzzy appearance or a dry, brown look. It can affect almost every part of the plant and can kill a perennial. Like other plant pathogens, botrytis will stay dormant in dead plant material and can be spread easily to other plants even after a winter of dormancy. Gray mould thrives in humidity, and it is spread in water. Heuchera may be affected when stagnant water sits on the leaves during extreme fluctuations of humidity. Fungicides may help cure botrytis, but prevention through care in watering practices, good air circulation between huecheras and proper disposal of infected material is the best treatment.
Two-spotted Spider Mite
Although not technically a disease, spider mites can spawn 20 or more generations in one year. Known as red mites, the U.S. variety are most often green in appearance, with two spots on their backs. A spider mite emits a silken thread that eventually will leave a weblike appearance if left untreated. The danger in these insects is the damage they cause when they feed on leaves, which looks similar to a disease. The heuchera will have tiny yellow to white dots on the leaf surface, and leaves can turn brown and completely die back if not resolved. An insecticide in the form of a soap or spray, applied every 2 to 3 weeks, will rid your heuchera of unwanted guests.
Routine care of heuchera will produce plants that are more resistant to illness and healthier producers. When planting heuchera, space them an adequate distance apart to ensure air circulation. Water only when needed, and fertilise with a rich organic matter when planting. Pinching old blooms will encourage new growth. The heuchera grows in woody crowns that will get sparse in the middle over time. Digging up these crowns and splitting them apart, then replanting with soil contact to the crown, is essential for proper development and health.
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