What Is Wrong With My Guava?

Are there any orange, rust-colored, dense, silky tufts on both upper and lower surfaces of leaves that turn reddish-purple as they mature?

Are there any sunken, dark-colored lesions on mature fruit which may become covered in pink spores?

Are there any small irregularly shaped or roughly circular dark brown lesions with darker brown border on the upper surface of leaves?

Are the leaves pale on their upper side and are there any dusty blisters on the undersides?

Are there any depressions in fruit with dark-colored puncture wounds; soft, mushy areas on fruit caused by larvae are present?

Do the fruits ripe prematurely and dry up, fruit insides may have fermented?

Are the leaves covered in a sticky substance and may have growth of sooty mold?

Are the leaves covered in coarse stippling and may appear silvery?

Algal leaf spot is caused by algae Cephaleuros virescens and it's favored by wet, humid conditions. Zoospores can be spread by splashing water. Ensure trees receive adequate fertilization, irrigation and are properly pruned to avoid stress on the plants and promote air circulation through the canopy. Periodic applications of a copper-based fungicide are usually enough to control the disease.

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

Pseudocercospora leaf spot is a fungal disease that infects guava during wet conditions when temperatures are between 55 and 77°F. Spray plants with copper as soon as symptoms appear to prevent further symptom development.

Likely cause for these symptoms is a fungal disease - Rust. Provide good air circulation around plants by thining them. Avoid making leaves wet when watering. All infected leaves should be removed. Spray leaves with sulfur early in the season to prevent rust or to treat mild infections.

Two types of fruit flies attack guava, Guava fruit fly, and Caribbean fruit fly. Infested fruit should be removed and destroyed. Plowing around bases of trees infested with guava fruit flies exposes pupae to damaging heat from the sun and to natural enemies. Millions of sterile Caribbean fruit flies are introduced yearly in Florida to control populations on citrus.

Guava Weevil is the most serious pest on guava trees. This insect can cause up to 70 to 100 % yield loss. Collect and burn the damaged fruits. Soil application of entomopathogenic nematodes (EPN) like genus Heterorhabditis and Steinernema as biological control agents against 4th larval instar, pre-pupa, and pupa weevil stages.

Guava leaves covered by the sticky substances are caused by scales. These tiny, shelled insects often feed on the undersides of the leaves, causing an unhealthy appearance. Scrape off minor infestations with your fingernail. Prune out badly infested growth, or use a soft brush and soapy water to gently scrub the scales off the stems. Control scales by spraying insecticidal oil during the growing season.

These symptoms may indicate thrips. Thrips are tiny, yellow to black flying insects. They hide under the leaves. Severely infected plant parts should be removed and destroyed. Control thrips by introducing lady beetles or lacewings, their natural predators. Insecticidal soap helps in severe infestations.

Yellow, stunted plants and roots that have swollen galls indicate root-knot nematodes. Other symptoms are plants wilting during bright, hot days. Prevent root-knot nematodes by applying chitin or introducing parasitic nematodes to the soil before planting. Solarizing the soil also helps in preventing root-knot nematodes.