How to prevent and control lettuce brown spot disease causing water-soaked leaves with mold and dry wilt
Lettuce brown spot disease affects the leaves, with two types of symptoms: first, lesions initially appear water-soaked, then gradually expand into circular or irregular brown to dark gray lesions, ranging from 2-10 mm in diameter. Second, dark brown lesions with irregular edges and a water-soaked halo around the outside. On wet lesion surfaces, dark gray moldy growth appears; in severe cases, the lesions merge and the leaves turn brown and dry up.
Lettuce brown spot disease
Lettuce brown spot disease spreads, proliferates and infects through seed-borne pathogens and wind and rain. Generally, warm and humid weather, frequent rain, and long periods of heavy fog and dew favor the occurrence and epidemic of brown spot disease. In soils with insufficient fertility, where lettuce grows poorly, or where nitrogen fertilizer is applied excessively and growth is overly lush, the disease is aggravated.
Measures for preventing and controlling lettuce brown spot disease:
(1) Before preparing the soil, first clean the field, deep plow and sun the soil, then apply an appropriate amount of lime and sufficient organic base fertilizer.
(2) During the planting management period, pay attention to reasonable irrigation; topdressing should have a reasonable balance of nitrogen, phosphorus and potassium, and foliar fertilizers such as Zhibaosu and Lufengsu should be sprayed to promote robust growth of lettuce and improve resistance.
(3) Before the lettuce rows close or at the early stage of disease onset, spray promptly. Optional pesticides: Baikening or chlorothalonil (40% suspension concentrate) at 600 times, Baijunazole (50% sulfur-carbendazim wettable powder) at 800-1000 times, thiophanate-methyl or Pujunke (70% ultra-micro compound wettable powder) at 1000-1500 times, iprodione (50% wettable powder) at 1500 times, Xin'erpu (65% wettable powder) at 400 times, Baoning (60% carbendazim-thiram wettable powder) at 600-800 times. Spray once every 7-10 days, for 2-3 consecutive times.