Lettuce planting: how to prevent and cure the brown spot of lettuce?

Last year, it was found that there were brown spot disease and black spot disease in lettuce planting. How to control lettuce brown spot disease? There are no netizens to guide the prevention and control of brown spot and black spot on lettuce: lettuce brown spot and black spot are considered to be harmful to leaves. Lettuce leaf spots harmed by brown spot show two symptoms: one is water-stained at first, then gradually enlarged into round or irregular shape, brown to dark gray spot, with a diameter of 2-10 mm. Another kind is dark brown disease spot, the edge is irregular, the periphery has the water stain shape halo. Dark gray mildew occurs on the moist spots, and in severe cases, the disease spots merge with each other, until the leaves turn brown and dry. Black spot, also known as ring disease, leaf blight, forms round to nearly round brown spots on the leaves, and the size of the spot varies greatly under different conditions, generally 3-15 mm, brown to grayish brown, with concentric wheel lines, and no mildew can be seen in the field. Insufficient soil fertility, poor growth of lettuce, or excessive application of nitrogen fertilizer will aggravate the disease. Control methods of lettuce brown spot and black spot: 1. Clean the fields before soil preparation, and apply appropriate amount of lime and sufficient organic base fertilizer after deep sun exposure. 2. During the period of planting management, we should pay attention to rational irrigation, rational combination of nitrogen, phosphorus and potassium with topdressing, and spray foliar fertilizer such as phytoprotegerin, Lufengsu, etc., so as to make the plant grow healthily and improve the resistance. 3. we should pay close attention to spraying before the long seal of lettuce or in the early stage of the disease. The choice of agents are: chlorothalonil or chlorothalonil (40% suspending agent) 600x, chlorozole (50% polysulfide wettable powder) 800,800 times, methyl thiophanate or promethazine (70% ultrafine compound wettable powder) 1000-1500 times, promethazine (50% wettable powder) 1500 times, Xinerpu (65% wettable powder) 400x, Baoning (60% Fuke wettable powder) 600,800 times. Spray every 7-10 days for 2-3 times in a row. Click for more lettuce planting techniques click to get more vegetable planting techniques