Protecting your pittosporum from disease includes proper watering and pruning practices.

Disease Control for a Variegated Pittosporum

by Sarah Moore

Busy moms have a friend in variegated pittosporum (Pittosporum tobira “Variegata”), a tolerant plant that grows well in U.S. Department of Agriculture plant hardiness zones 8 through 11. Despite its easy nature, pittosporum can be affected by diseases. While you shouldn't stress about management, follow basic safety procedures. Wear gloves, and keep sharp implements and chemicals away from children. Some variegated pittosporum diseases cannot be cured, so the old maxim holds true: Prevention is the best medicine.

1. Galls and Dieback

Unfortunately, galls and diebacks usually cannot be treated. They enter the plant through fresh wounds made by trimming, so use precaution when trimming. Take care to clean your equipment as you go along, as open wounds such as the type created by clipping are easy entrances through which a plant can contract disease. Clean blades with 70 percent isopropyl alcohol or a 10 percent bleach solution between every cut.

2. Leaf Spot

Leaf spots are caused by a variety of fungus types and manifest in spotted, discolored leaves. Your best bet is to prevent these from occurring in the first place. By trimming trees and hedges with an eye to good airflow, you can keep air circulating in the center of the plant. This helps water evaporate so it won’t encourage fungus and other pathogens overnight and reduces the chance of an infection growing without you noticing. Cultural controls to prevent the disease are more effective than fungicides, but if you really feel you need one, get an expert opinion about both the disease and the appropriate response.

3. Rhizoctonia Aerial Blight

Pittosporums are particularly susceptible to Rhizoctonia aerial blight, which is a problem in hot, humid weather where conditions favor the development and growth of fungus. Prune diseased stems 6 inches below any sign of infection. To avoid disease, keep the plant free of weeds to reduce resource competition and potential incubators of disease. Water during the day to give the plant's leaves, stems and trunks a chance to dry before nightfall. This reduces the amount of time it spends wet and cool, favoring disease conditions.

4. Root Rot

Plants with root rot drop leaves, exhibit leaf curling and manifest dead, black outer roots as well as diseased or dead feeder roots. The best way to control root rot is to water variegated pittosporum lightly. It tolerates drought but not soggy feet, and standing in water almost guarantees a rot problem. When you plant it, ensure well-drained soil by incorporating organic matter and position it away from areas that sometimes have standing water.

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