Symptoms of infestation:
Harms adult and old leaves. Disease spot produced in the leaf surface or leaf edge, the initial brown spots, and then gradually expand into a round, nearly round and irregularly shaped large plaque, the central gray-white, on the small black grains, the edge of the brown.
Occurrence:
Ophiobolussp. is called serpentine spore cavernous fungus, belonging to the fungus of the subphylum Hemiptera. The pathogen is mainly transmitted by wind and rain. The disease is serious in summer when it is high humidity and rainy, often resulting in defoliation. Sloppy planting management, orchard shade, poor drainage will induce the disease serious occurrence.
Prevention methods:
1, strengthen the cultivation management, reasonable fertilization, increase the application of organic fertilizers, improve orchard drainage, in order to promote the growth of the root system; moderate pruning and pruning, to enhance the ventilation and light penetration, in order to improve plant resistance to disease.
2, good orchard health, after harvesting to do a good job of clearing the garden in a timely manner, the removal of dead branches and leaves and diseased branches and leaves centralized burned to reduce the source of bacteria.
3, on the sick orchard and old trees, to strengthen the summer and fall season orchard inspection; in the early stages of the onset of spraying, the interval of 10-15 days of drug application, continuous spraying 2-3 times. Pharmacies can be used: 70% thiophanate-methyl wettable powder 800-1000 times; 75% Chlorothalonil wettable powder 600-700 times; 50% carbendazim wettable powder 500-800 times; 50% isobutyl urea wettable powder 1000-1500 times; 10% benzyl urea wettable powder 1000-1500 times; 10% benzyl urea wettable powder 1000-1500 times; 10% benzyl urea wettable powder 1000-1500 times. -The above agents should be used alternately. The above agents should be used alternately.