Rose black spot has become a major problem in rose cultivation, and leaves, twigs and pedicels can suffer. When the disease is serious, all the lower and middle leaves of the whole plant fall off, leaving only a small amount of new leaves on the top, which directly affects the growth, flowering and ornamental of the rose. First, briefly introduce the symptoms and the incidence of the disease. The lesion on the leaf was initially a purple-brown to brown dot and later expanded into a round spot of 1.5 to 13 mm in diameter, black or dark brown. The lesions are often surrounded by yellow halos. The pathogens overwinter on diseased branches or fallen leaves with mycelium or conidium discs. Infestation starts from May to June. The temperature of 17°C to 25°C is the optimal temperature for onset, and the incidence of disease above 30°C is reduced. Conidia spread by rain or sprinkling, and insects can spread. It is prone to disease when it is rainy, foggy and exposed. The incubation period is from 10 days to 13 days. Germs can be repeatedly infested and can develop throughout the growing season. Rose black spot should be prevention-based, timely prevention and control in the early stages of disease will be more effective, once the late, it is difficult to control its spread with drug control. Through years of practice, the author explored a set of effective prevention and control methods. First of all, choose as good as possible disease-resistant varieties. Second, strengthen cultivation management. It is best to use drip irrigation, furrow irrigation or watering along the edge of the pot, not watering at night, so as not to dry quickly when there is water on the leaves, the invasion of bacteria is advantageous. Trim in time to allow the plants to be airy and clear, with sufficient light, and at least 6 hours of light per day. Less nitrogen fertilizer during the onset, more phosphorus and potassium fertilizer. Third, clean leaves at any time, remove diseased leaves, and reduce the source of infection. Severe pruning of severely diseased plants in winter eliminates overwintering pathogens on diseased stems. Do not touch the leaves of diseased plants with your hands to prevent human transmission. Fourth, chemical control. There are many drugs for controlling black spot, and soil disinfection can be performed in early spring with 1% of arsenic. In addition, in the spring leaves or early onset, spray with 45% Thiabendazole 500 to 600 times, or 70% chlorothalonil wettable 500 times, alternately. Use, once every 7 days to 10 days, more than 3 times in a row, the control effect is better. At the time of onset, 800 times 50% of carbendazim solution can be sprayed. This drug is resistant to rain erosion. The use of chlorothalonil alone is more effective than carbendazim. Practice has proved that the use of traditional Bordeaux liquid to prevent rose black spot disease is still an effective method. Because this drug has strong adhesiveness in the wet weather of the rose season, a layer of film can be formed on the leaf surface, which can effectively kill the bacteria. Bordeaux fluid efficacy can be maintained for 2 weeks. Because of the long incubation period of the black spot pathogen, it is better to control the spraying time before the onset of the disease and the effect will be better. Bordeaux fluid is 100 times liquid lime equivalent, and it should be used immediately. Don't overnight. Potato Slicer,Potato Slicer For Chips,Automatic Potato Slicer,Potato Slicer Machine Guangzhou New Power Catering Equipment Manufacturing Co.,Ltd , https://www.gznewpower.com