Guava Diseases: Control of Damping-Off, a Common Disease of Guava

What should you do when damping-off occurs in guava, how should you control it, and what do the symptoms look like? Let's take a look together.

Symptoms:After different guava varieties are harmed by the damping-off pathogen, apart from differences in the strength of disease resistance, the symptoms also differ slightly. Generally, after infection with damping-off, 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 fade to a yellowish-green color, the leaf shape becomes smaller, and there are occasionally red spots. It often starts from the tip of a single 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 and down to the roots, finally causing the plant to wither; for the Li Ba strain and the Bai Ba strain, the symptoms mostly appear on new leaves. After Li Ba and Bai Ba are infected, raised areas appear on the surface of the trunk, and pale pink spores appear beneath the raised areas. In the later stage, when the outer bark separates, a large amount of spores grows inside; this is the symptomatic characteristic of these two strains; for the Thailand Ba strain, this phenomenon is not easily seen on the outer bark. When infected with damping-off, the mature leaves on the branches tend to turn yellow more easily, the branches wither, and it gradually spreads downward and sideways, finally causing the death of the whole plant. However, 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 stage, which has an enormous impact on growers' income. Guava of any size will be harmed. If guava seedlings are planted in the original planting holes of dead fruit trees, 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 apply asphalt, paint or Nan Pao resin to protect the wound.

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, replaced with new soil, and then planting should be carried out.

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