Damage and Control of Cucumber bacterial Corner spot

Bacterial angular spot is one of the main diseases on cucumber, which has been gradually aggravated in recent years. Prevention and control measures should be taken as soon as possible.

Cucumber can occur from seedling stage to adult stage, which mainly harms leaves and occasionally occurs on melons and vines. When the leaves are infected, the chlorotic dots appear first, and then enlarge, and the disease spots are grayish white or yellowish brown polygonal due to the limitation of leaf veins. When the humidity is high, there is an obvious watery green halo on the periphery of the disease spot, milky white water bead-like bacteria pus appears on the disease spot, and there are membranous white marks after drying. In the later stage, the plaque was dry, cracked and perforated. When the disease is serious, the plaques are connected to each other and show light brown oil-paper plaques. Stem vine infection, at the beginning of the water stain-like small spot, and then the longitudinal expansion is a short strip, when the humidity is high, there is bacterial pus, when the disease is serious, the vine longitudinally crack. Watery dark green nearly round sunken spots were formed at the initial stage of melon infection, and then expanded into irregular light brown disease spots, with dirty white bacterial pus overflowing, and cracks or stench decay occurred in serious cases. The vascular bundles of diseased plants and melon flesh turn brown.

Agricultural control: disease-resistant varieties are selected for ⑴. Jinchun No. 1, Jinzao No. 3 and other varieties have strong disease resistance and can be selected according to local conditions.

⑵ seeds were sterilized. Soak the seeds in 55 ℃ warm water for 15 minutes before sowing, remove them and put them in cold water to cool down, or soak the seeds in 40% formalin solution for 90 minutes, rinse with clean water and then germinate and sow.

⑶ rotation. Raise seedlings with disease-free soil and rotate with non-melon crops for more than 2 years.

⑷ strengthens field management. Deep ditch narrow border cultivation, three ditches matching, enhance the ability of waterlogging prevention and drainage in the rainy season. Apply sufficient base fertilizer and increase phosphorus and potassium fertilizer to prevent excessive application of nitrogen fertilizer and enhance plant disease resistance. The cultivation of cucumber in open field should be popularized to protect cucumber from rain. In protected field, cucumber should be watered less, ploughed frequently, ventilated more frequently, humidity in greenhouse reduced, condensation and dripping reduced.

Second, chemical control: to control cucumber bacterial corner spot, spray with 14% ammonia copper solution, or 47% plus Ruinong wettable powder, or 50% nail cream copper wettable powder, or 72% agricultural streptomycin soluble powder 4000 times at the initial stage of the disease. Spray once every 7-10 days, and the frequency of application is determined according to the condition. Copper preparation should not be used more than 3 times to avoid drug damage.