Common vegetables can cause blight and bacterial wilt, such as watermelon, melon, cucumber, melon, broad bean, cowpea, pepper, tomato, potato, etc. Fusarium will occur; pepper, tomato, potato, eggplant and some legumes will occur With blight, bacterial wilt also occurs. These two diseases are very common in vegetables, and they occur seriously, often causing 3-5 percent loss or even loss of vegetables. Therefore, it is especially important to correctly distinguish and identify these two diseases and take corresponding measures to prevent them.
First, the identification of two diseases
These two diseases often occur simultaneously on vegetables, and some of the external symptoms are very similar. The common remarkable feature of the two diseases is that they belong to the same vascular bundle disease, which is characterized by wilting and withering of the plants. In the early stage of the disease, the leaves and top tips are sag, especially at noon or strong light, but can return to normal in the morning and evening; in the middle of the disease, the diseased plants are pulled up, the stalks are examined, and the vascular bundles have changed. It turns brown; at the end of the disease, the diseased plants wither and die. Although the symptoms are very similar, they can be distinguished by careful diagnosis of the field and monitoring of the whole process of the disease.
1. The types of pathogens that cause disease are different.
Fusarium wilt is a fungal disease caused by the genus Fusarium oxysporum, and the bacterial wilt is a bacterial disease caused by Pseudomonas aeruginosa.
2. The speed of plant wilting is different.
The disease has a rapid onset of bacterial wilt. From the beginning of the onset, it only takes 4-6d to wilting and dying. It is characterized by acute wilting of the whole plant, while the wilt disease begins to sag from the leaves, withering to death, it takes 12-15d. The speed and time of wilting are 8-9 days slower than the former.
3. The wilting sites and order of the diseased plants are different.
The wilt diseased plant begins with the lower leaves and wilts from bottom to top. The color of the leaves gradually fades from green to yellow, and then turns brown. The leaves do not fall off at all, and the whole plant is dead. The plants are short and the tender stems are bent.
For example, melon wilt can cause disease during the whole growth period, and the disease is most serious from flowering to melon. The seedlings are ill, the roots are few, the leaves are shrinking, and then the whole plant is dying. During the flowering and melon period, the leaves wilted from bottom to top, and the daytime wilting occurred immediately after the onset of the disease. It returned to normal in the morning and at night, and was dead after 10 days, which was easy to pull up.
For example, tomato wilt disease begins to manifest after colonization. In the early stage of the disease, the leaves that are generally closer to the ground are yellow, and finally brown and dead, and the dead leaves remain on the stems; the leaves on one side of the stem are yellow, and the leaves on the other side are normal; there are also leaves on individual branches. The yellow side is yellow and the other half is normal. When the disease is serious, the diseased leaves expand from the bottom to the top, and only a few leaves at the top remain, and the rest are dead. The incidence is light, except for the yellow leaves of the leaves closer to the ground, the rest are normal. The root of the diseased plant showed brown rot or local necrosis. The vascular bundle was yellowish brown when the base of the stem was cut. The main symptom of the disease is that the leaves of the plant are yellow after the disease, and the pink mold is often found at the base of the stem when wet. Moreover, the root cause of bacterial wilt is small.
There are different degrees of dryness in the leaves of tomato bacterial wilt. At the same time, there are adventitious roots at the bottom of the plants. Tomatoes appear hollow inside the stems of the plants, and the tomatoes with wilting symptoms can clearly see the color of the vascular bundles. It has turned brown. It is precisely because these vascular bundles have been destroyed that nutrients and water cannot be transported normally upwards, which causes the tomatoes to appear wilting symptoms.
The bacterial wilt disease is different from the wilt disease in that it is the young leaves, young shoots and newly developed young leaves of the upper apex. Not equal to the yellowing and discoloration of the leaves, the whole plant will quickly lose water and wither and wither. For example, the bacterial wilt of pepper, tomato and potato is characterized by green leaves and green branches.
4. The symptoms of the diseased plants are different.
When the wilt diseased plant is wet, the base of the stem (vine or vine) can see yellow-white or pink mildew, which is the conidiophore and conidia of the fungus.
Such as melon wilt disease, common brown streaks at the base of the vines or longitudinal cracks in the epidermis. When wet, there is a resinous gel overflowing, the vascular bundle of the stem is brown, the vine is watery and rot, and white corn pink mildew appears on the surface. The stems, leaves, branches and other parts of the bacterial wilt surface only showed signs and no signs (pathogens). Only when the diseased stem is cross-cut and the discolored vascular bundle is squeezed by hand, only the white bacterial liquid overflows, which is its pathogenic bacteria. If the cross-cut stem is immersed in a glass bottle containing light salt water, it can also be seen that the milky white mist is ejected from the incision, which is of course also a pathogenic bacteria.
Second, the prevention and control measures of the two diseases
Vegetable blight and bacterial wilt are two incurable diseases that are difficult to cure. They can be transmitted through the soil, seeds, fertilizers, manure, water streams and wounds caused by farming operations. The pathogen invades from the root wound and the root hair, secretes venom in the crop conduit, blocks the catheter, affects the normal transportation of water and nutrients, and causes the crop to die. The conditions of the disease are high temperature, high humidity (20-25 ° C, 80% relative humidity suitable for the disease), heavy planting, partial application of nitrogen fertilizer, poor irrigation and drainage, fertilizer not decomposed, lack of phosphorus, less potassium, etc. Causes the occurrence of blight and bacterial wilt. At present, there is no pesticide that effectively cures these two diseases, and it is necessary to adopt comprehensive control techniques to be effective.
1, a reasonable rotation, away from the source of bacteria. The pathogens of blight and bacterial wilt are "soil habits". The disease of Fusarium wilt is overwintered in the soil by the mycelium, thick stalk or sclerotium of the fungus, and can be rotted for 5-7 years in the diseased body; the bacterial wilt can also overwinter in the soil with the diseased residue. Survival for 14 months to 7 years. Therefore, as long as the two kinds of pathogens remain in the soil, the disease is affected year by year. Therefore, 2-5 years of rotation should be carried out on the land that has already occurred, or the effect of water and drought rotation is better. At the same time, before planting, the diseased plants should be completely removed and burnt, no diseased plants are used for fertilizer, no unfertilized organic fertilizer is applied, and agricultural operations are minimized to reduce the wounds of vegetable plants, improve irrigation and drainage conditions, and avoid bacterial sources in many ways.
2. Breeding and popularizing resistant varieties. The pathogens of blight and bacterial wilt have physiological race differentiation, while different races have different pathogenicity and host range. Therefore, it is possible to breed and promote disease-resistant vegetable varieties, which is an effective way and necessary measure to resist and alleviate diseases. Generally, early-maturing tomato varieties are resistant to bacterial wilt, and have been promoted with anti-green 19, Hong Kang No. 1, No. 2, No. 28, No. 3, Xiangdao No. 1, Qiuxing, Xiangyin; Anti-No. 1, Anti-Qing No. 1, Yue Hongyu, Yue Xing, Xia Xing, Feng Shun, Zai You No. 1, No. 2 and other varieties. The varieties resistant to tomato wilt are Xi'an Dahong, Qiang Mi Shou, Mansi, Su Kang No. 3, Qi Zao No. 3, Qi Kang No. 4, Qiangfeng, and Florid. The varieties resistant to watermelon wilt are Jingxin No. 1, Qiliang No. 1, Hongdou, Dafengxin, Jinzhong Guanlong, Duoli, Xindeng, Longhua, Longbao, Jingkang No. 2, No. 3, Zheng Kang No.1 No. 2, Zhengzhou 8902, 8903. Anti-cucumber wilt disease is Jingyan No.5, No.7, Jinza No.1, No.2, No.3, No.4, Jinchun No.4, Zaofeng No.2, Zhongnong No.5, etc. Harvest No. 1, Jinzhou Double Season Bean, Nine, Qingdao Bean, Chunfeng No. 1, No. 2, Qiu Kang 19, etc.; varieties resistant to cowpea wilt are Guangdong pig intestine, Zhuyan, Xiyuan, Jietu 1 Changde beans and so on. The varieties resistant to pepper bacterial wilt are Zazao No. 2 and Tongjiao No.1. In addition, Zhejiang used CHZ-26 as an anti-disease rootstock to graft eggplant, and Hainan used pumpkin as a rootstock to graft watermelon against blight, and large-scale cultivation has been successful.
3, seed and vegetable seedbed disinfection, eliminate the source of bacteria. 1 seed treatment. Soak in warm water or hot water. This method is effective for both wilt and bacterial wilt. The specific method is to soak the tea with 3-4 times of seed weight 3-4 times of warm water for 15 minutes, while stirring and soaking, until the water temperature drops to about 36 °C, stop stirring, and then soak for 4-5h to germination sowing; melon seeds germination For a long time, you can use hot water to scald, use the same amount of water, temperature 70-75 ° C, pour the melon seeds into it, and then use another small bucket to repeatedly dump, when the hot water drops to a little hot, then stir for 10min Just fine. 2 disinfection of the drug. Bacterial wilt can be soaked in 600 times solution of trichloroisourea for 6-8h. Control against blight and bacterial wilt can be soaked in 40% formaldehyde 100 times solution for 15 minutes. Fusarium wilt can be seeded with 50% thiram WP at a seed weight of 0.3% to 0.4%. The vegetable seedbed can be replaced with disease-free bed soil and disinfected with 70% thiophanate-methyl WP or 50% carbendazim WP carbendazim WP, 75% disulfide SP400 times liquid seedbed.
4. Suppress the spread of pathogens. Fusarium is easy to develop on sticky soils, acidic soils and plots with acidic fertilizers. Soil pH 5-5.6 is the most susceptible to disease. Therefore, lime can be applied to adjust soil pH and inhibit disease development. Fusarium wilt and bacterial wilt suddenly encounter high temperature or long-term high temperature after a long rain, and even the rain and hot weather after the drought, it is easy to explode, and the film is wilting and dead. Therefore, in the whole process of cultivation, the field temperature and humidity should be adjusted, the soil should be kept dry, dehumidification and de-staining, deep gully and high ridge, proper close planting, timely pruning, moderate retention of melons and preserved fruit, keeping the field ventilated and transparent, creating a good The ecological environment, the application of organic nutrition, phosphorus, potassium, micro-package fertilizer Jiamei profit, to promote balanced growth, flowering period 2-3 times 800 times liquid Jiamei brain white gold, gold spots. These fitness cultivation management measures can have an immediate effect on inhibiting the spread of disease and increasing the immunity of plants against disease. Spraying 2% pyrimidine nucleoside antibiotic AC 500 times solution at the initial stage of the disease has a certain effect on preventing and preventing disease outbreaks.
5, chemical control. Apply some high-efficiency, low-toxic, low-residue pesticides to kill and control the bacteria. Control and control of wilt disease can be rooted and sprayed with 70% thiophanate-methyl WP500-600 times solution or 50% carbendazim WP400 times solution, 40% aluminum triethyl phosphite WP500 solution; 72% agricultural sulfuric acid chain can be used to control bacterial wilt WP4000 times liquid irrigation, spraying or 14% copper ammonia AS400 times solution or 50% succinic acid copper WP400 times solution, 77% copper hydroxide WP400 times liquid root spray control, for blight, dryness The disease is effective.
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