Cucumber brown spot mostly starts from the cucumber melon period, and the middle and lower leaves begin to develop and develop upward. At the beginning, small gray-brown spots appeared on the leaves and gradually expanded into unequal round or near-circular edges of light brown or brown spots of unequal size. The lesions are mostly 8 to 15 mm in diameter, 3 to 5 mm in size, and 20 to 25 mm in size. The lesions in the middle of the lesions become lighter, sometimes grayish and grayish brown on the edges. When the humidity is high, sparse grayish-brown moulds are sparse on the front and back of the lesion. Sometimes the lesions fuse and the leaves are yellow. When the disease is heavy, oval taupe lesions appear on stems and petioles.
Control methods:
1 seed disinfection
When grafting cucumbers and squash, it is important to note that the seeds of the squash also need to carry no bacteria. Soak cucumber seeds and grafted black seed pumpkin seeds for 30 minutes with warm water at 55°C.
2 Agricultural measures
Onset fields should be rotated for more than two years with non-melon crops. Thoroughly remove the sick plants in the field and deep-deep the soil in order to reduce the source of field infestation. Apply enough basal fertilizer, timely fertilizer, avoid partial nitrogenous fertilizer, increase phosphorus and potassium fertilizers, apply appropriate amount of boron fertilizer. To prevent the premature decline of cucumber plants, pay attention to exhalation after watering, remove diseased leaves in the early stages of disease.
3 Chemical control
In the early stage of disease, 75% chlorothalonil WP can be used in time, 500% of 70% Mancozeb WP, or 50% WP WP can be added 65% zeocin WP (1: 1) 500 times, or 75% chlorothalonil wettable powder plus 70% carbendazim wettable powder (1:1) 500 times, or 75% chlorothalonil wettable powder plus 50% fastinking wettability Powder (1:1) 1000 times liquid and other agents spray, once every 7 days, continuous control 2 to 3 times.
Chlorine-containing preparation is the earliest and most widely used drinking water disinfectant, which is of great significance for carrying out disinfection and ensuring disinfection effect. Chlorine in drinking water
Effective chlorine is a method to characterize the oxygenation capacity of chlorine-containing disinfection liquid with chlorine gas as the standard. The effective chlorine content in disinfectant venom is taller, disinfect ability is stronger, kill
Kill microorganisms more thoroughly. Residual chlorine refers to the residual chlorine content in the water after the disinfectant has been used for a certain period of time. If sufficient residual chlorine is maintained after chlorination of the water,
It shows that not only the disinfection effect is reliable, but also the continuous disinfection effect. This speed test paper is a kind of broad-spectrum chlorine test paper, used to determine the disinfectant
Whether the effective chlorine content reaches the disinfection application value, whether the residual chlorine content in the water can ensure the disinfection effect and whether the concentration is too high and affect the sensory properties of the water is very important
To cause secondary chemical pollution .
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