Disease Control for a Variegated Pittosporum

Root Rot

• Tolerant of a range of soils, pittosporums require only that you plant them in spots with good drainage. Never plant them where water accumulates from the roof or gutters. They're frequently included in foundation plantings, but make sure rainfall is quickly dispersed from the area. Otherwise, the moisture can inundate the plant's root system and rapidly lead to death from root rot disease. Once the roots have been affected, nothing can be done. Prevention is key, with careful site selection and, perhaps, the addition of sand to improve drainage.

Leaf Spot

• Fungal leaf spot diseases such as alternaria often strike pittosporums, as well. Using fungicides with copper, mancozeb, iprodione, thiophanate methyl, fludioxonil or propiconazole as active ingredients should provide some relief. Rotating between these or choosing a fungicide with a combination of the ingredients can reduce the potential for fungicide resistance. Only a little of the product should be applied, such as 4 ounces per 100 gallons of water, at intervals of once every three weeks. Never use chlorothalonil fungicides -- they may cause leaf drop or even death, particularly for variegated cultivars. Chlorothalonil labels indicate that it is not safe for pittosporums. Above all, provide your plant with good air circulation, avoid overhead watering and remove any fallen leaves promptly.

Physiological Disorder

• Though not a disease, a magnesium deficiency may develop in variegated pittosporum when the soil pH is too high. If you notice yellowing on the edges or between the veins of a mature leaf, chances are it lacks magnesium. Add sulfur as an acidifying agent. Buy the pelletized form, which spreads more uniformly and does not pose the inhalation hazard of the powdered type. For a quick remedy, mix the amendment thoroughly into the top 6 inches of soil. Otherwise, spread it over the soil, and allow it to gradually settle into the ground.

Prevention

• Along with specific steps to avoiding waterlogged locations and amend alkaline soils, giving a Japanese mock orange proper general care lowers its susceptibility to disease. It grows well in both sun and shade, and adapts to all types of well-drained soil. Quite drought-tolerant after it reaches 10 feet tall, it needs regular, thorough watering while becoming established. Prune only immediately after flowering, or you may remove next year's flower buds if you prune too late in the season. Cover the shrub during cold spells, because the bark can split from freeze damage, allowing fungal infections to enter through the wounds. If all goes well, pittosporums generally have long lifespans.