Why Does My Starfruit Tree Look Unhealthy?

Are there any orange, rusty pustules on leaves, stems, twigs, and fruit, the tissue is often seen swelling?

Are there any small, circular light brown or black spots on the skin of fruits, lesions develop sunken centers and olive-brown spores?

Are there any tiny, slightly depressed light to dark brown spots that expand and make fruit soft?

Are there any tiny necrotic or chlorotic spots on leaflets, spots grow larger and develop gray-white centers, reddish-brown margins, and chlorotic halos?

Are there any small black dots in a roughly circular pattern on the surface of fruit which can be rubbed off?

Algal disease on star fruit is caused by Cephaleuros virescens. Wet and humid environments promote this disease. Algae is spread by water splash. Maintain proper irrigation, pruning, and fertilization regimes in starfruit plantations. Copper-based fungicides may be required to control the disease in severely infected plantations.

Alternaria black spot or brown spot is a fungal disease that spreads by wind and rain and enters the plant through wounds. Avoid wounding fruits during harvest and you shouldn't have many problems.

These symptoms indicate a fungal disease - Anthracnose. The primary method of controlling the disease is to plant resistant cultivars. Both systemic and non-systemic fungicides are effective at controlling the disease and are usually applied shortly before flowering and during fruit development.

Cercospora leaf spot is a fungal disease transmitted by rain splash, wind, insects, and irrigation water. This fungal disease only occurs in very warm climates. Spots develop a “frog-eye” appearance with light centers and dark edges. Spray plants with copper as soon as symptoms appear to prevent further symptom development.

Flyspeck is a fungal disease with similar symptoms to fly feeding damage. Disease emerges in warm, wet conditions. Flyspeck is controlled with the fungicides that are effective for apple scab. Growing season applications of copper or sulfur sprays can help in the control of the disease. Pruning trees to encourage air circulation also helps.

If the canopy has a sparse appearance, wilts during periods of water stress, and the foliage is showing symptoms of nutrient deficiencies your starfruit may have suffered from Pythium root rot. Plant only disease-free nursery stock. Plant in areas with no history of the disease. Avoid planting trees in low lying areas.