Plant Health Problems
Diseases caused by Fungi:
Anthracnose, Glomerella spp.
Symptoms first appear as brown or necrotic areas at the ends of leaves and look like a tipburn. Affected tissues are tan at first and turn brown with age. The fungus grows into the leaf from the tip until the entire leaf is affected. These leaves turn brown and drop.
Control strategies include careful attention to watering since these fungi can be easily spread with splashing water. Additionally, watering early in the day helps to minimize the chance for long periods of leaf wetness which favor disease. Other methods that maximize air circulation by plant spacing to avoid crowding and well-balanced fertilization and good cultural care help to minimize problems. Picking and removing symptomatic leaves also helps in control since it reduces the amount of the fungus available to spread to healthy leaves. Although fungicides are rarely necessary, control can also be achieved with the use of fungicide sprays applied as soon as symptoms are visible. Among the compounds registered for use in Connecticut are copper hydroxide and thiophanate methyl. Consult the label for dosage rates, safety precautions, and indoor use.
Diseases caused by Physiological/Environmental Factors:
Raised, scab-like swellings appear on the undersides of the leaves. These first appear as water-soaked blisters and may turn rusty-brown with age. This condition is often associated with inadequate light levels as well as overwatering, especially during periods of cloudy, cool weather.
This problem can be minimized by careful attention to moisture levels in the potting mix, especially during cloudy weather.