What are the control methods for water lily leaf rot?
[Symptoms]It commonly affects the emergent leaves. In the early stage of the disease, chlorotic spots appear on the leaf surface of water lilies, the surrounding tissue necroses, and later expands into irregular lesions, light brown to dark brown. On floating leaves, dark to dark gray large spots with indistinct concentric rings appear, scattered with small black dots, causing the leaf margins to die back. In the late stage of the disease, many small black dots are scattered on the lesions, namely the pycnidia of the pathogen.
[Pathogen and disease pattern]The pathogen is Phyllosticta hydrophila, belonging to the Deuteromycotina, genus Phyllosticta. The pycnidia are nearly spherical or flattened spherical, brown. The fungus overwinters as pycnidia on diseased fallen leaves. Conidia are spread by wind and rain, invading through wounds or directly. High temperature and high humidity favor the onset of water lily disease. The disease period is from May to September. After October, the fungus forms pycnidia on diseased residual leaves to overwinter, becoming the primary infection source for the following year. Before water lilies bloom and in the early flowering stage, the disease is relatively mild; from the late flowering stage to the seed-setting stage, the disease develops rapidly. Tank-grown plants are more severely affected than pond-grown lotus, and small-tank grown plants suffer more severe disease. High temperature, high humidity and rainy seasons favor the spread of the disease. The timing and severity of water lily disease occurrence are mainly related to air temperature and relative air humidity.
[Control methods]① Plant new disease-resistant water lily varieties. ② When scattered disease occurs, promptly remove diseased leaves to avoid spreading damage. ③ Advocate the application of compost fermented with effective microorganisms. ④ In the early stage of the disease, spray 36% thiophanate-methyl suspension concentrate at 500 times dilution, or 75% Daconil wettable powder at 1000 times dilution plus 50% carbendazim wettable powder at 1000 times dilution, or 27% high-fat film at 200 times dilution plus 70% mancozeb wettable powder at 800-1000 times dilution, or 1:1:100 equal-ratio Bordeaux mixture, or 27% copper hydroxide suspension concentrate at 600 times dilution.
Symptoms and control of lotus leaf rot
Lotus [Nelumbo nucifera Gaertn. Nymphaeaceae]
[Symptoms]Leaf lesions mostly occur between the radial leaf veins, initially appearing as small chlorotic dots, then expanding into nearly circular to irregular spots, with brown to purple-brown edges and gray-brown to gray-white centers; small dots of varying density are scattered on the spot surface. The lesions may merge with each other into patches, and the lesions easily rupture and fall off to form holes, in severe cases leaving only the main veins, causing the lotus leaf to look like a broken umbrella.
[Pathogen and disease characteristics]The pathogen is Phyllosticta hydrophila Speg. of the Deuteromycotina. The fungus overwinters as mycelium and pycnidia on diseased residues, and conidia are spread by wind and rain to newly emerging lotus leaves for infection; the conidia produced in the diseased parts then cause repeated infection. High temperature and high humidity favor the onset of the disease, and the disease develops very rapidly from the flowering stage to the seed-setting stage of the plant. Poor fertility or excessive application of nitrogen fertilizer makes plants more susceptible to the disease. Resistance varies among varieties; in Wuhan, Hubei, Fenlou Chun and others are more susceptible, while Yinhong Qianye and Xihu Honglian and others are more resistant.
[Control methods]
① Remove diseased residues.
② Select good disease-resistant varieties.
③ Strengthen fertilizer and water management, apply more potassium fertilizer, and avoid excessive nitrogen and excessively high water temperature (>35°C).
④ In the early stage of the disease, spray for protection before or after wind and rain; alternately spray 0.5% Bordeaux mixture, or 30% copper oxychloride + 75% chlorothalonil (1:1) at 800-1000 times dilution, or 80% Daconil wettable powder at 500 times dilution, or 40% flusilazole emulsifiable concentrate at 8000 times dilution, or 50% thiabendazole aqueous solution at 1500 times dilution, or 50% Sportak wettable powder at 1000 times dilution, or 69% Anke mancozeb + 75% chlorothalonil wettable powder (1:1) at 1500 times dilution, or 25% myclobutanil emulsifiable concentrate at 8000 times dilution, 3-4 times, spraying once every 7-15 days depending on the weather.
Symptoms and control methods of lotus leaf rot
Lotus [Nelumbo nucifera Gaertn. Nymphaeaceae]
[Symptoms]Leaf lesions mostly occur between the radial leaf veins, initially appearing as small chlorotic dots, then expanding into nearly circular to irregular spots, with brown to purple-brown edges and gray-brown to gray-white centers; small dots of varying density are scattered on the spot surface. The lesions may merge with each other into patches, and the lesions easily rupture and fall off to form holes, in severe cases leaving only the main veins, causing the lotus leaf to look like a broken umbrella.
[Pathogen and disease characteristics]The pathogen is Phyllosticta hydrophila Speg. of the Deuteromycotina. The fungus overwinters as mycelium and pycnidia on diseased residues, and conidia are spread by wind and rain to newly emerging lotus leaves for infection; the conidia produced in the diseased parts then cause repeated infection. High temperature and high humidity favor the onset of the disease, and the disease develops very rapidly from the flowering stage to the seed-setting stage of the plant. Poor fertility or excessive application of nitrogen fertilizer makes plants more susceptible to the disease. Resistance varies among varieties; in Wuhan, Hubei, Fenlou Chun and others are more susceptible, while Yinhong Qianye and Xihu Honglian and others are more resistant.
[Control methods]
① Remove diseased residues.
② Select good disease-resistant varieties.
③ Strengthen fertilizer and water management, apply more potassium fertilizer, and avoid excessive nitrogen and excessively high water temperature (>35°C).
④ In the early stage of the disease, spray for protection before or after wind and rain; alternately spray 0.5% Bordeaux mixture, or 30% copper oxychloride + 75% chlorothalonil (1:1) at 800-1000 times dilution, or 80% Daconil wettable powder at 500 times dilution, or 40% flusilazole emulsifiable concentrate at 8000 times dilution, or 50% thiabendazole aqueous solution at 1500 times dilution, or 50% Sportak wettable powder at 1000 times dilution, or 69% Anke mancozeb + 75% chlorothalonil wettable powder (1:1) at 1500 times dilution, or 25% myclobutanil emulsifiable concentrate at 8000 times dilution, 3-4 times, spraying once every 7-15 days depending on the weather.