The disease mainly damages the aboveground part of Begonia plants. The specific symptom is that in the early stage of the disease, the affected parts will appear sporadic white mould spots, and gradually expand into a piece, the leaves will turn yellow, fall off, or even do not bloom. Too much nitrogen, poor ventilation, planting too dense and so on are easy to induce powdery mildew.
The control methods are as follows:
① control the use of nitrogen fertilizer;
(2) spray 400-600 times of 60% zineb wettable powder every two weeks before the onset of the disease, and spray 1000 times of 70% Thiophane methyl or 1000-2000 times of 15% fenxiuling in the early stage of the disease.
In spring and cloudy days, the disease is serious. The symptoms are as follows: in the early stage of the disease, dark spots in the shape of water stains will appear on the stems and leaves of the plants, and gradually expand, white filaments will appear on the diseased parts, and brown granules will appear after drying up.
Prevention and treatment: in the early stage of the disease, you can spray carbendazim or 65% diclosone 600-800 times solution.
The disease is harmful to the whole plant, especially the stem. At the early stage of the disease, the stem appeared water spot, and gradually expanded into soft rot, making the plant lodging. When the humidity is too high and the plants are too dense, the disease is easy to occur. The control methods are as follows:
① pay attention to ventilation and light transmission, control humidity;
In the early stage of the disease, spraying 1500 times of 70% methyltobramycin or 800-1000 times of 50% dianthammonium every 10 days can effectively prevent and treat the disease.
The symptoms are as follows: in the early stage of the disease, the lesions are bullous, the color changes from dark green to transparent yellow, and gradually expands to dark brown dry spots, with white mucus on them. In the later stage, perforation and rupture will lead to plant death. The control methods are as follows:
① often disinfect the flower soil.
② the planting density should be reasonable, pay attention to ventilation and light transmission, and avoid splashing on the leaves when watering. Remove the diseased leaves in time.
③ when the disease is serious, spray 72% agricultural streptomycin 4000 times solution in time.
