In late August last year, many plants in the large cherry production area of ​​Qinhuangdao City suffered from severe brown spot disease. The leaves produced brown spots, yellowed, and quickly fell off, which greatly affected the yield and quality of this year's cherries. Recently, when the author went to the countryside, he discovered that the disease had signs of starting or becoming heavy in many gardens. The fruit farmers friends must do a good job in preventing and treating the disease.
First, the cause of serious brown spot
According to research, the cause of severe cherry brown spot disease in Qinhuangdao City is mainly due to the lack of relevant knowledge of fruit growers, and it is not recognized that fruit management after harvesting is also very important, especially to protect the leaves. The status quo: First, the medication is too little. Some fruit growers were able to spray 1-2 times in a timely manner just after harvesting fruits, but after a longer period of time, they relaxed their management and felt that the fruit had been harvested, and spraying two medicines was sufficient. The second is that the interval is too long. Some fruit farmers can also spray 3 times after harvest, but the spraying interval is too long, and some are more than 30 days. The third is the wrong way to use drugs. There are fruit farmers in the leaves have more or obvious lesions, it is still using mancozeb and other protective fungicides to prevent diseases.
Second, the occurrence of brown spots
The pathogenic bacteria overwintered on the damaged leaves, and the ascospore and ascospores were produced when the temperature and humidity were appropriate in the following year. The winds or raindrops spread to infect the leaves. In July and August, the incidence was the heaviest, which could cause early defoliation, and often led to secondary flowering in August-September. The severity of general disease is related to tree vigor, precipitation, and management level. It has weak tree vigor, heavy precipitation, low-lying terrain, poor drainage, and the lack of timely or inappropriate treatment.
Third, prevention and control measures
We must establish correct guidelines for prevention and control. The quality of high cherry cherries and their quality are closely related to the quality and preservation rate of the leaves in the previous year. Therefore, in the prevention and control measures, we must pay attention to protecting the leaves.
1. Make a good foundation. For example, on the basis of spraying 5 Baume degree lime sulfur at the initial stage of germination and spraying mancozeb and other protective agents after flowering, the medium and late-maturing varieties should be sprayed with a systemic effect after 15-20 days of pre-harvest and after all the fruits have been harvested. The bactericides such as quizbutine and carbendazim are used for prevention and treatment.
2. Onset of spraying a good therapeutic drug. In July and August, when more or more lesions are found in the lesion, it is best to spray the agent that has the eradication effect on the bacteria, such as tebuconazole or Sedol. If there is damage from apple moths, gypsy moths, and mites, spray leprosulfil, diflubenzuron, and abamectin may be added.
3 spray good preventive medicine. If the previous medium-term prevention work has been very good, there are very few related lesions, pests and plagues. In the early stage, it can spray 1:2:200 times Bordeaux mixture + 4000 times 1.8% abamectin 2-3 times.
4. Grasp the interval and multiples. The period of spraying during the cherry growth period is usually 20-30 days. The concentration of the drug is generally recommended to be the average multiple of the relevant pesticide when it is used for prevention; when the disease is severe or when it is treated, the most concentrated multiple is appropriate.
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