What is the performance of cucumber brown spot? What are the treatments?

Cucumber brown spot, also known as target spot, is commonly known as "small yellow spot". In recent years, it has become one of the main diseases endangering cucumber production in protected areas. the incidence rate is generally 20% to 40%, and when it is serious, it can reach 60% to 70%. Causing fallen leaves, fruit and other phenomena. What is the performance of cucumber brown spot? What are the treatments?

First, what is the performance of cucumber brown spot?

Most of the disease began from the peak stage of cucumber, and the middle and lower leaves developed first and developed upward. At the initial stage, small gray-brown spots appeared on the leaf surface, and gradually expanded into light brown or brown spots with irregular edges, which were round or near-round in size. Most of the lesions are 8-15 mm in diameter, 3-5 mm in size and 20-25 mm in diameter. In the later stage, the color in the middle of the lesion becomes lighter, sometimes grayish white, and the edge is grayish brown. When the humidity is high, there are sparse grayish brown mildew on the front and back of the disease spot. Sometimes the disease spots fuse and the leaves are withered and yellow. When the disease is serious, oval grayish-brown spots will also appear on the stem vine and petiole.

Seeds can carry bacteria, and the carrying rate is not high, and more bacteria can be isolated from pumpkin seeds. Therefore, even if cucumber seeds are not infected with bacteria, when inoculated with pumpkins, the bacteria carried by pumpkin seeds can also become the source of initial infection. The pathogen overwintered in the soil and spread by airflow or Rain Water spatter for the first time, and the conidia formed by the disease spot after the initial invasion spread around by wind and rain. The transmission of conidia usually takes place in the daytime, and the peak time of conidia transmission is at 14: 00:00. The conditions of temperature and humidity are suitable, and the bacteria invade quickly. The disease is serious under the condition of 25-28 ℃ and saturated relative humidity, and the environmental condition with large temperature difference between day and night will aggravate the disease. The disease is serious when the plant is weak, partial application of nitrogen fertilizer and trace element boron deficiency. Increasing the application of phosphorus and potassium fertilizer can alleviate the disease.

Second, what are the treatments for cucumber brown spot?

1. Seed disinfection

When cucumber and pumpkin are grafted, it should be noted that pumpkin seeds are also bacteria-free. Soak cucumber seeds and grafted black seed pumpkin seeds in 55 ℃ warm water for 30 minutes. (mixed with live Pseudomonas fluorescens 3 hours before sowing and seeded after shade drying.

2. Agricultural measures and chemical control

Timely use of effective biological pesticides for prevention and treatment, the diseased field should be rotated with non-melon crops for more than 2 years. In the land without conditional rotation, the living bacteria of Pseudomonas aeruginosa were used to irrigate roots and spray leaves to ensure that all kinds of diseases and insect pests caused by heavy stubble bacteria were eliminated. At the same time, living bacteria of Pseudomonas fluorescens can improve the soil and increase the content of organic matter in the soil. kill all kinds of harmful bacteria caused by picture-borne diseases. Thoroughly remove the diseased and residual plants in the field and turn the soil deeply, so as to reduce the source of initial invading bacteria in the field. Apply sufficient base fertilizer, timely topdressing, avoid partial application of nitrogen fertilizer, increase phosphorus and potassium fertilizer, and apply appropriate amount of boron fertilizer. To prevent premature senescence of cucumber plants, pay attention to ventilation and dehumidification after watering, and remove diseased leaves at the initial stage of the disease.