Occurrence and control of ginger plague

1. Symptoms

Pathogens attack roots and underground and aboveground stems. The injured underground fleshy stems were initially water-stained and yellow-brown. After losing luster, the internal tissues gradually softened and rotted, leaving only the outer skin. Squeeze the diseased part can flow out dirty white turbid juice, smell; the injured root is also pale brown, and finally all rot. The injured stems are dark purple, the internal tissues turn brown and rot, and the residual fibers. The leaves were withered, pale yellow, curled at the edge, and finally the whole plant died.

2. Pathogen

The disease is caused by infection with Pseudomonas solanacearum. The optimum temperature for growth and development is 28 - 29℃, the highest 40℃, the lowest 4℃, and the lethal temperature is 52 - 53.3℃(10 minutes). Bacteria in the dry state of about 30℃, 3 days after the loss of vitality, in the pH range of 4.05 - 9.5 bacteria can grow, but pH 5.4 - 7.3 is the most suitable. In addition to ginger, eggplant, pepper, tomato, potato and so on can be infected.

3. Source and spread of bacteria

The pathogen existed in soil and infected ginger tissue, and could survive for more than 2 years in soil. After planting in the next year, the pathogen in the diseased ginger seed or soil with bacteria invaded the underground stem base of ginger plant or directly caused the disease of underground ginger under suitable environmental conditions. Compared with soil, diseased ginger is more likely to cause disease, and the time is faster. Both of them are important sources of disease that can not be ignored. Ginger blast, like other flagellated rod-shaped bacteria, must have water in order to spread. Generally spread by irrigation water, surface running water, underground pests and rain splash spread. Planting susceptible varieties, cleaning diseased soil for years, using ginger with strains, improper fertilization, and high temperature and humidity environmental conditions are easy to cause the occurrence and epidemic of ginger plague.

4. Conditions of disease

One is to have the existence of disease source (diseased ginger seed and soil with bacteria); the other is to have suitable environmental conditions for disease. Environmental conditions mainly refer to temperature (air temperature and soil temperature) and rainfall of climatic conditions. Generally, when the average temperature of ten days reaches about 24℃, the disease begins to spread, and when sufficient rainfall is added at about 28℃, water in the field is formed, and the disease develops rapidly. The results showed that temperature (especially soil temperature) and rainfall were two important factors which caused the epidemic of the disease, especially the ponding of ginger field after rain and the exposure to the sun. In addition, improper irrigation before and after emergence of ginger seedlings has a certain induction effect, improper cultivation management or rotation time are closely related to the occurrence of diseases. When the average temperature of soil is above 25℃, the incubation period is generally 6 - 8 days, the shortest 3 days, the longest 11 days, and 41 days at 15 - 20℃. High temperature and humidity, sunny and rainy weather, especially the drastic changes in soil temperature conducive to the occurrence of epidemic disease. The amount of rainfall is also related to the morning and evening of rainfall. From June to July, if the rainfall reaches about 100 mm within 10 to 12 days, the diseased plants can appear in the field, and about 1 week after heavy rain, the field will have a peak incidence. The disease incidence was high in continuous cropping, low-lying, sticky soil, no mulch and partial N fertilizer application, the central diseased plant appeared early, the number of reinfection was more, and the disease occurred seriously.

5. Law of occurrence and fluctuation

Ginger blast usually starts from mid-May to early June in open field cultivation. Due to the low temperature and low rainfall during this period, the disease occurred sporadically and spread slowly. Late June and early July were the periods of occurrence of central diseased plants and formation of middle heart disease mass in large area, and the peak period of occurrence and epidemic of ginger plague was from late July to middle September. At this time, it is a high temperature and high humidity climate, ginger block formation expansion vigorous period, bacteria easy to invade, infection speed is fast, serious can cause the whole field in about 15 days, the whole peak of the disease can last 50 - 60 days. After the middle of September, with the decrease of temperature and rainfall, the disease gradually reduced, and stopped after the middle of October. The whole disease period lasted for about 140 days.

6. Comprehensive control measures

Control strategies must be based on comprehensive measures based on agricultural control, try to create environmental conditions that are not conducive to disease occurrence, and pay close attention to the coordination of various links.

6.1 Choose resistant varieties. There were differences in resistance among varieties, Yiwu Shoujiang, Xinchang Xiaozhubian ginger and Zhejiang Tiegenqing were more resistant.

6.2 Choose disease-free ginger seeds. Establish disease-free cultivation, select disease-free ginger seeds, all have water stains, skin easy to fall off or open ginger blocks visible black-brown ring patterns, with hand extrusion white juice overflow, are diseased ginger blocks, can not be planted.

6.3 Disinfection of ginger seeds. Methods The same method was used to select seeds for detoxification.

6.4 crop rotation. Select high terrain, good drainage plot, deep ploughing after the application of quicklime 100 - 150 kg per mu, high ridge, increase the application of phosphorus and potassium fertilizer or cover shade, implement more than 2 - 3 rotation, avoid continuous cropping or interplanting with Solanaceae crops.

6.5 Strengthen field management. Pay attention to drainage of ginger field, strictly control irrigation of ginger field, generally adopt artificial irrigation, and strictly prohibit field immersion irrigation. Deep ditch, high compartment, timely drainage of accumulated water after rain

Heavy application of base fertilizer, light application, clever application of topdressing, avoid excessive application of nitrogen fertilizer, increase phosphorus, potassium fertilizer and coarse residue fertilizer. When the central diseased plant is found, it shall be uprooted immediately, and the soil in the nest shall be taken out of the field for treatment, and the vicinity shall be disinfected with fresh lime.

6.6 Chemical control. During seedling stage, 300 kg of 500 times solution of 78% Jiangwening was used to irrigate the nest. At the beginning of the disease, the damage of ginger plague can be effectively controlled by pouring or spraying 78% Jiangwenning 300 - 500 times solution every 5 - 7 days for 2 - 3 consecutive times, or pouring 72% streptomycin sulfate 3000 times solution, or 1000 units of neophytin 3000 times solution, or pouring 90% aluminum triethylphosphonate soluble powder 300 times solution.