What is lettuce brown spot? Diseases you need to know when growing lettuce
What is lettuce brown spot? What harm does lettuce brown spot cause? How do you prevent and control lettuce brown spot? We also invite fellow gardeners to help explain. The harm and control methods of lettuce brown spot are provided for reference as follows (reference provided by Zhongdiwang). Harm of lettuce brown spot: lettuce brown spot mainly damages the leaves; the lesions on the leaves...
What is lettuce brown spot? What harm does lettuce brown spot cause? How do you prevent and control lettuce brown spot? We also invite fellow gardeners to help explain.The harm and control methods of lettuce brown spot are provided for reference as follows (reference provided by Zhongdiwang).
Harm of lettuce brown spot:
Lettuce brown spot mainly damages the leaves; the lesions on the leaves show two types of symptoms. One begins as a water-soaked spot at the early stage of disease, then gradually expands into a round to irregular shape, producing brown to dark gray lesions 2-10 mm in diameter; the other is a dark brown lesion with irregular edges and a water-soaked halo around the outside.
When environmental humidity is high, dark gray mold-like growth appears on the lesions, and in severe cases the lesions merge with one another, causing the leaves to turn brown and dry up. The first type of brown spot symptom is caused by Cercospora longissima, while Cercospora musae causes the second type of brown spot symptom.
Lettuce brown spot occurs and worsens during continuous rainy or snowy weather, when plants grow poorly, or when excessive nitrogen fertilizer is applied alone, causing overly vigorous growth.
Control methods for lettuce brown spot
1. Clean the field: promptly carry diseased plant debris out of the field and burn it.
2. Reasonable fertilization: adopt formula fertilization techniques, apply more organic fertilizer and phosphorus and potassium fertilizers, avoid applying nitrogen fertilizer alone, so that the plants grow vigorously and their disease resistance is enhanced.
3. Chemical control:
At the early stage of disease, spray 40% carbendazim-sulfur suspension concentrate at 500 times dilution, or 75% chlorothalonil wettable powder at 1000 times dilution plus 70% thiophanate-methyl wettable powder at 1000 times dilution, or 50% iprodione wettable powder at 1200-1500 times dilution, or 60% fosetyl-aluminum wettable powder at 500 times dilution, etc., spraying about once every 10 days for 2-3 consecutive treatments. Stop applying the chemicals 5-7 days before harvest.
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