Control Methods for the Common Guava Disease Southern Blight

What should you do when guava develops southern blight, how should you control it, and what do the symptoms look like? Let's take a look together.

Symptoms:After guava varieties are harmed by the southern blight pathogen, besides differences in resistance, the symptoms also vary slightly. Generally, after infection with southern blight, the main symptoms mostly appear on new buds; the new buds turn brown or black, and after the new shoots stop growing, the new leaves turn pale yellow-green in color, the leaf shape becomes smaller, and there are occasionally red spots. It often starts from the tip of a certain branch of the whole plant, and the disease gradually spreads downward, and from the fork it infects new branches to produce new disease sites; the disease gradually develops toward the base of the trunk down to the roots, finally causing the plant to wither; the Li Ba strain and the Bai Ba strain mostly show symptoms on new leaves. After Li Ba and Bai Ba are infected, the trunk surface develops raised bark, and pale pink spores appear below the raised areas; later, when the bark peels off, a large amount of spores grows inside. This is the symptom characteristic of these two strains; for the Thailand Ba strain, this phenomenon is not easily seen on the bark. When infected with southern blight, the mature leaves on the branches tend to turn yellow, the branches wither, and it gradually spreads downward and sideways, finally leading to the death of the whole plant, but pale-colored powdery spores appear only on the cross-section of the cut branches, which is a slight difference from the symptoms of the old strains.

After field plants are infected, the symptom of the whole plant dying occurs during the fruit ripening period, which has an enormous impact on farmers' income. Guava of any size can be harmed. If guava seedlings are planted in the original planting hole of a dead fruit tree, they will also wither within 1 to 2 years, depending on how quickly the root system of the new plant is infected and the degree of damage.

Control methods:

1. Handling of diseased plants:

1. When diseased branches are found, saw them off at the fork and immediately coat the wound with tar, paint or Nan Pao resin to protect it.

2. The sawed-off diseased branches and fallen leaves should be collected and burned.

2. Replanting: When replanting, the old soil near the original plant should be dug out and replaced with new soil before planting again.

3. Abandoning cultivation: When more than 30% of plants are diseased, cultivation should be abandoned, the plants dug out and burned on site, and the orchard replanted with other crops.