How to prevent and control papaya brown rot? Methods for dealing with fruit that develops spots, rots and becomes mummified

Papaya brown rot

    1. Symptoms: Brown rot mainly damages papaya fruit, and also damages flowers and young shoots. When fruit is affected, brown nearly round spots appear first, then as the disease develops they continuously expand; under suitable conditions they spread to the whole fruit and extend into the flesh, and in severe cases the entire papaya rots. After the diseased fruit loses water, it turns into a brown mummified fruit that hangs on the branch and does not fall for a long time. The pathogen on the flower stalk or on the papaya infects the branches, forming brown canker spots, which affect the normal transport of water and nutrients, inhibit branch growth, and cause the branches to die.

    2. Disease pattern: Papaya brown rot is a fungal disease. The pathogen overwinters on mummified fruit, and the pathogen on diseased branches can also cause infection after overwintering. In the spring of the following year, after the temperature rises, the pathogen on diseased fruit and diseased branches produces conidia, which spread by wind and rain. Around early May, after young fruit has formed, the pathogen mostly invades through wounds on the papaya. Therefore, where insect pests are severe and there are many insect wounds, brown rot is also severe.

    3. Prevention and control methods:

    1. Dispose of diseased residues. After the papaya harvest, in combination with winter pruning, cut off diseased branches, remove diseased fruit, and burn them in a centralized manner, which can effectively reduce the overwintering sources of inoculum.

    2. Chemical control. In early spring before the papaya sprouts, spray 1 time with 5 degrees Baume lime sulfur mixture; from March to April, after the papaya flowers fade until before harvest, every 10-15 days spray 1 time with 50% carbendazim 500 times or 50% thiophanate-methyl 800 times solution, spraying 2-3 times in succession, which can also control leaf diseases.

    3. Prevent insect wounds. The peach fruit borer is an important pest damaging papaya. In mid-to-late June, when the papaya fruit expands, the female moth lays eggs in the depression of the papaya stalk and in the gaps along the seams; after the larvae hatch, they bite through the fruit skin and bore into the fruit. They not only feed on the flesh in strings, but also create insect wounds, which facilitate pathogen invasion. Control method: during the larval hatching period, spray 90% crystalline trichlorfon 1000 times solution or fenitrothion emulsion 1500 times solution, once every 7 days, spraying 3 times in succession.