What are the control methods for loquat trunk rot disease?

In recent years, loquat trunk rot disease has occurred especially severely in some places, posing a serious threat to loquat production. According to surveys, the varieties Luoyangqing and Dahongpao are the most susceptible to the disease. In the early stage of the disease, the base of the main trunk rots first, and then it gradually develops upward along the branches and trunk, while the diseased tissue spreads gradually from the xylem around the pith toward the surrounding areas. Severely affected plants show acute rotting of branches and trunk, causing the upper branches and leaves to wither rapidly. For trees with a larger canopy, it takes only a few days in summer from the onset of disease to the withering of the whole plant; for older trees with a larger canopy, it takes about 1 year from the onset of disease to death, and a small number of trees can survive for more than 2 years. In affected areas, after young trees are infected, the mortality rate is as high as more than 80%, and for trees just beginning to bear fruit it is about 73%. The following measures can be taken for control:

In the experiment, the Luoyangqing variety was selected, and in severely affected areas and adjacent lightly affected areas, for diseased trees at the initial fruiting stage and full fruiting stage, four types were classified by disease severity: severe, moderate, mild, and healthy plants (control), and different fungicides and different application methods were used for control treatments.

Before applying the fungicide, first loosen the soil within the drip line of the diseased tree canopy to a depth of 15-30 cm, then choose the following fungicides for control: (1) Carbendazim and Thiophanate-methyl 50x solution, 0.25-0.5 kg per tree mixed into medicated soil, evenly spread on the loosened soil under the canopy, and then turn the medicated soil under the soil; (2) Formaldehyde 100x solution, 50-70 kg per tree poured at the roots; (3) Formaldehyde 100x solution, 50-70 kg per tree poured at the roots; (4) Formaldehyde 100x solution and Thiophanate-methyl 50x solution injected into the trunk (drill a downward-sloping hole 5-7 cm deep at the base of the trunk, inject the solution under pressure, and after 10 minutes seal the hole opening with clay).

The experimental results show that the above control methods have no control effect on severely diseased trees, have a relatively good control effect on moderately diseased trees, and have a significant control effect on lightly diseased trees and a health-protecting effect on healthy trees; among them, Carbendazim and Thiophanate-methyl at 0.25-0.5 kg per tree poured at the roots and Thiophanate-methyl 50x solution injected into the trunk ranked next. It can thus be seen that for this disease, emphasis should be placed on early prevention and early treatment, and at the early stage of disease when the condition is still mild, Carbendazim and Thiophanate-methyl 50x solution should be applied to the soil at 0.25-0.5 kg per tree.