Lettuce Cultivation: How to Prevent and Control Lettuce Brown Spot and Black Spot?
Last year, brown spot and black spot were found in lettuce cultivation. How to prevent and control lettuce brown spot and black spot? Are there any netizens' guidance methods to prevent and control the harm of brown spot and black spot to lettuce: Both lettuce brown spot and black spot mainly damage the leaves. Lettuce leaves harmed by brown spot show two types of symptoms: one...
Last year, brown spot and black spot were found in lettuce cultivation. How to prevent and control lettuce brown spot and black spot? Are there any netizens' guidance methods for prevention and controlThe harm of brown spot and black spot to lettuce:
Both lettuce brown spot and black spot mainly damage the leaves.
Lettuce leaves harmed by brown spot show two types of symptoms:One type initially appears water-soaked, then gradually expands into circular or irregular brown to dark gray lesions, ranging from 2-10 mm in diameter.
The other type is dark brown lesions with irregular edges and a water-soaked halo on the outer margin. On moist lesion surfaces, dark gray mold-like growth appears. In severe cases, the lesions merge with each other, causing the leaves to turn brown and dry up.
Black spot, also known as ring spot or leaf blight, forms circular to nearly circular brown spots on the leaves. Under different conditions, the lesion size varies considerably, generally 3-15 mm, brown to grayish brown, with concentric rings. No mold-like growth is visible in the field.
Insufficient soil fertility, poor lettuce growth, or excessive nitrogen fertilizer causing over-luxuriant growth will all aggravate the disease.
Prevention and control methods for lettuce brown spot and black spot:
1. Before land preparation, 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 rational irrigation, apply nitrogen, phosphorus and potassium in a reasonable combination for topdressing, and spray foliar fertilizers such as plant protection agents and Lufengsu to promote robust plant growth and improve resistance.
3. Before lettuce rows close or at the early stage of disease onset, spray promptly. Available fungicides include: Baikening or chlorothalonil (40% suspension concentrate) at 600 times, baijunazole (50% carbendazim-sulfur 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.
Click to get more lettuce cultivation techniques
Click to get more vegetable cultivation techniques