Common Guava Diseases and the Latest Control Methods

Guava is a fruit tree that grows in tropical and subtropical regions and is one of the better-known fruits of the subtropics. Guava is highly adaptable to the environment, especially since it has few requirements for soil, and it is very easy to cultivate. However, being easy to grow does not mean it is easy to produce a high yield; during cultivation it also encounters many pests and diseases, so the control of guava pests and diseases is very important. Below I will talk with you about the common pests and diseases of guava.

1. Guava leaf blight

Leaf blight mainly harms guava leaves. In the early stage, brown irregular patches appear on the leaves, and in the middle and later stages they gradually turn light brown, with the diseased areas clearly demarcated from the healthy areas. In the later stage, the entire leaf becomes infected until it withers. Leaf blight is mainly caused by fungal pathogens overwintering in diseased plant residues and soil; when the rainy season comes, they begin to reproduce and spread, invading the leaves. The orchard should be cleaned up in time, and the diseased residues should be gathered and burned to reduce the source of the disease. When the disease is found, sprays such as chlorothalonil wettable powder can be used for control, once a week for one month.

2. Guava Pseudocercospora brown spot

Pseudocercospora brown spot mainly harms guava leaves and fruit. Brown irregular patches appear on the leaves, with indistinct edges, and gray mold-like growth appears on the underside of the leaves. Small black spots appear on the fruit skin, the middle of the fruit becomes sunken, and the edges of the depression are reddish brown. This is mainly due to Pseudocercospora spreading and dispersing between diseased trees and healthy trees; excessively high humidity is the time when the disease incidence is highest. When diseased leaves and fruit are found, they should be removed in time and destroyed together. Prune diseased branches to reduce the chance of disease, and spray carbendazim wettable powder and other agents to disinfect the orchard.

3. Guava sunscald fruit disease

Sunscald fruit disease generally occurs on the sun-facing side of the fruit. At first, small water-soaked spots appear on the fruit, then they become brown patches that are somewhat sunken. In the later stage, all the patches spread to form one large patch. This disease is not originally caused by fungal pathogens; it mainly begins when the sun-facing side is scorched by the sun, which allows pathogens to invade. It mainly occurs in the high-temperature season of summer in July and August, when pathogens lurking in diseased residues and soil invade the scorched fruit and cause the disease. Remove diseased residues from the orchard, protect fruit exposed to the sun, and disinfect the orchard to reduce the source of the disease.

4. Guava root-knot nematode disease

Root-knot nematode disease is mainly caused by the larvae of root-knot nematodes invading the roots of guava trees, causing the root tips to bend and gradually swell into an oval shape, with fewer fibrous roots, making it impossible to normally absorb and transport nutrients. For control methods, an area with no root-knot nematodes and fertile soil can be chosen to establish the orchard, disease-resistant varieties can be selected, and the soil can be improved to reduce the presence of root-knot nematodes.

For varieties without disease resistance, diseases are relatively easy to occur. Observe the changes in guava trees carefully every day, and if any abnormality is found, immediately determine the type of disease so that the right treatment can be applied in time. In daily management, preventive measures should still be taken well. Diseases are extremely harmful to crops and can cause severe yield reduction or even total crop loss.