Water lily brown spot prevention

Brown spot is a common disease in the growth of water lilies. At the time of the initial development, the leaves appeared pale yellow spots, then gradually expanded into round or near-circular lesions, brown, with a diameter of 0.6 to 10 mm. As the disease progresses and aggravates, the lesion can reach 1/3 to 1/2 of the leaf area, the leaf color changes from green to yellow, the leaf margins are dry and involute, the entire leaf is scorched at the later stage, and a layer of dark green leaves and petioles appear. Fluffy hair. The flowering plants of the affected plants were delayed in flowering and did not even bloom; in severe cases, the leaves of the whole plant were scorched until they died.

The disease is caused by the infection of the fungus Cercospora maculatus of the fungus Sporotrichum sp. The pathogens overwinter with mycelium in diseased leaves and debris. Conidia produced from May to June of the following year were affected by wind and rain. From July to August, the incidence was the most serious. High temperature and humidity were important factors in the development of diseases. Especially during the storm, when the leaves were damaged or flooded, they were very conducive to the infection of pathogens and often caused the rapid spread of diseases. The leaves are too dense, poorly transmitted, and susceptible to insect attack.

Prevention can be started from the following aspects.

Strengthen cultivation management. In addition to the selection of robust, disease-free cultivation of underground stems, during the growth period, the old leaves should be timely and sparsely cut, both to reduce the source of infection and enhance light transmission. Rational application of nitrogen, phosphorus, and potassium fertilizers to promote robust plant growth and increase resistance to disease.

Strengthen protection. During the stormy season, protective measures should be taken to prevent wind damage to the leaves and flooding the plants.

Chemical control. Before the onset of illness, one or two equal doses of 1:1:100 Bordeaux mixture can be sprayed to effectively prevent the occurrence of diseases. In the early stage of the disease, spray 65% ​​zein zinc WP 800 times, or 50% carbendazim. Wettable powder 600 times liquid, once every 7 to 10 days, even spray 3 to 4 times, can effectively control the spread of the disease.