Ratoons dwarfing disease (Ratoonstuntingdisease),
In 1954, China's Taiwan Province first reported the occurrence of this disease. China's Guangdong Province and Fujian Province have also reported the occurrence of this disease one after another. Other sugarcane planting areas have not been reported so far. This disease is heavier in the more arid cane area and causes greater losses.
(A) Pathogen The pathogen Clavirbacterxylisubsp.xyliDavisetAl is a Coryneform bacterium. The bacteria is present in the vascular bundle of diseased cane. The bacteria has a unique morphology. The bacteria are straight or slightly curved, slender, thin-walled, sometimes with one end swelled, and there are interstitials in the body, not swimming, and Gram-staining. Positive.
The bacteria are not evenly distributed in diseased sugarcane plants, and the number of bacteria in the diseased plants is reduced in the following order: 1 the base of the stem base; 2 the internodes of the base of the stem; 3 the growth point; 4 the heart; Leaf blade; 6 leaf veins and sheath. The number of bacteria contained in a diseased plant is directly related to the severity of the disease.
(B) symptoms of the disease in the appearance of no typical external symptoms, only showed that the plant dwarf, stem diameter smaller, growth retardation, perennial hair growth. Diseased cane is very sensitive to soil water shortage, so it grows more slowly when it encounters drought. Those with severe illness will show withered state, or the leaves of the leaf margin will be dry. If the irrigation water is sufficient, it will cover up the appearance symptoms and reduce the loss.
The symptoms of the disease in the internal manifestations of the following two aspects: 1 In the young shoot stem growth points below 1 cm of the node tissue becomes orange-red. The depth of the color varies according to the variety, and some varieties do not show this symptom even when infected. At the same time, the amount of nitrogen fertilizer application will also affect the depth of the color. When the nitrogen fertilizer is used for a long time, the color will be deeper. When the nitrogen fertilizer is less, the color will be lighter. 2 The vascular bundles of the mature cane stems will change color from yellow to orange-red to dark red. It is most easy to see from the ground 1 to 10 knots, especially 3 to 8 knots. Vascular discoloration is generally confined to the nodules and rarely extends to the internodes. It is most noticeable at the branches of the vascular bundles at the nodules, especially at the branches of the vascular bundle to the leaf sheath. In the longitudinal section of the sugarcane plant, the discolored vascular bundles can be seen in punctiform, comma-like, or short-striped shapes; in the cross-section, the red vascular bundles can be seen as dots or stripes, and the red stripes can be seen as stalks. The center protrudes radially toward the leaf mark. The number of color-changing vascular bundles and the depth of color differ depending on the species and the age of the plants. Some of the sugarcane strains did not show such internal symptoms after infection.
(C) the incidence of disease law dwarfism is mainly spread through the cane knife and sugarcane species. Pathogens can survive for a longer period of time in the cane stalks of the seedlings or in the ratoon cane heads. In the next growing season, the seedlings or cane heads that are carrying the fungus grow plants that carry the bacteria. The cane knife or the harvester cutting the diseased sugarcane plantlet spreads the healthy sugarcane strain or the sugarcane plant when harvesting the healthy cane or when picking the cane plant. Roots contact between soil and sugarcane plants or mutual friction between the leaves can spread the disease. The sugar cane juice was diluted to 10000 times the liquid and the ability to infect. The contaminated sugarcane knife was still infectious in the shadowy place for 7 days. The disease is more severe with the longer the perennial period.
(IV) Control measures Seedling disease is the main factor in the transmission of the disease. Therefore, the selection of disease-free seedlings and sterilization of seedlings are the main measures for preventing and treating the disease.
1. Heat treatment of seedlings There are three methods: 1 hot water treatment. Treatment with 50°C hot water for 2 hours can prevent this disease. This method should be treated with double sprouts as well as full-stem seedlings. The disadvantage of this method is that the sugarcane buds are easily damaged, affecting the germination rate. 2 hot air treatment. The tool for hot air treatment is a large electric heated blast oven. The temperature and time are 54-58°C for 8 hours. If 58°C is used, the control rate can reach 100%. The advantage of hot air is that the equipment is relatively simple, and it is not easy to damage the sprouts, so the germination rate is higher. Disadvantages are long processing time, time-consuming, labor-intensive, and highly susceptible to water loss. Therefore, all stem seedlings must be used for treatment, and they should not be split into two buds. 3 air steam treatment. After mixing with steam and air, enter the treatment tank so that the temperature in the tank is maintained at a constant temperature to treat the sugarcane plant. It is generally treated at 53°C or 54°C for 4 hours. This method eliminates the disadvantages of hot water treatment of vulnerable shoots and hot air treatment that takes time and is prone to losing water.
2. Establishment of a disease-free nursery. The heat-treated seedlings will be planted in a centralized manner and the cultivation tools will be disinfected to provide disease-free seedlings for large-scale production. The disinfection of the tool can be wiped with 70% alcohol, and it can also be sterilized by flame burning.
3. During the cutting process, the cutting cane knife and the tilling equipment must be separated from the operating tools of other varieties, used separately, often sterilized, and the field rodents should be promptly eliminated. After the rapid propagation of tissue culture without pathogenic stem apex meristem, a large number of virus-free healthy tissue culture seedlings can be obtained, and after the first and second seedling breeding, healthy stems can be obtained for field production.
4. Before the next kind of deep plowing, fine soil preparation, full base fertilizer. Fertilizer is applied in a timely manner to prevent drought, so that fruit cane enhances resistance to disease.
5. In order to prevent the heat treatment and the original health of the sugarcane species once again being infected by the ratoon dwarf disease, the sugarcane field must be completely cleared of sugar cane, all appliances such as cane knife, seed drill, etc. must be used before boiling, steam or fire Bake for disinfection.
6. Eliminate rodent pests from voles and other bite fruit cane to prevent the spread of germs.
In 1954, China's Taiwan Province first reported the occurrence of this disease. China's Guangdong Province and Fujian Province have also reported the occurrence of this disease one after another. Other sugarcane planting areas have not been reported so far. This disease is heavier in the more arid cane area and causes greater losses.
(A) Pathogen The pathogen Clavirbacterxylisubsp.xyliDavisetAl is a Coryneform bacterium. The bacteria is present in the vascular bundle of diseased cane. The bacteria has a unique morphology. The bacteria are straight or slightly curved, slender, thin-walled, sometimes with one end swelled, and there are interstitials in the body, not swimming, and Gram-staining. Positive.
The bacteria are not evenly distributed in diseased sugarcane plants, and the number of bacteria in the diseased plants is reduced in the following order: 1 the base of the stem base; 2 the internodes of the base of the stem; 3 the growth point; 4 the heart; Leaf blade; 6 leaf veins and sheath. The number of bacteria contained in a diseased plant is directly related to the severity of the disease.
(B) symptoms of the disease in the appearance of no typical external symptoms, only showed that the plant dwarf, stem diameter smaller, growth retardation, perennial hair growth. Diseased cane is very sensitive to soil water shortage, so it grows more slowly when it encounters drought. Those with severe illness will show withered state, or the leaves of the leaf margin will be dry. If the irrigation water is sufficient, it will cover up the appearance symptoms and reduce the loss.
The symptoms of the disease in the internal manifestations of the following two aspects: 1 In the young shoot stem growth points below 1 cm of the node tissue becomes orange-red. The depth of the color varies according to the variety, and some varieties do not show this symptom even when infected. At the same time, the amount of nitrogen fertilizer application will also affect the depth of the color. When the nitrogen fertilizer is used for a long time, the color will be deeper. When the nitrogen fertilizer is less, the color will be lighter. 2 The vascular bundles of the mature cane stems will change color from yellow to orange-red to dark red. It is most easy to see from the ground 1 to 10 knots, especially 3 to 8 knots. Vascular discoloration is generally confined to the nodules and rarely extends to the internodes. It is most noticeable at the branches of the vascular bundles at the nodules, especially at the branches of the vascular bundle to the leaf sheath. In the longitudinal section of the sugarcane plant, the discolored vascular bundles can be seen in punctiform, comma-like, or short-striped shapes; in the cross-section, the red vascular bundles can be seen as dots or stripes, and the red stripes can be seen as stalks. The center protrudes radially toward the leaf mark. The number of color-changing vascular bundles and the depth of color differ depending on the species and the age of the plants. Some of the sugarcane strains did not show such internal symptoms after infection.
(C) the incidence of disease law dwarfism is mainly spread through the cane knife and sugarcane species. Pathogens can survive for a longer period of time in the cane stalks of the seedlings or in the ratoon cane heads. In the next growing season, the seedlings or cane heads that are carrying the fungus grow plants that carry the bacteria. The cane knife or the harvester cutting the diseased sugarcane plantlet spreads the healthy sugarcane strain or the sugarcane plant when harvesting the healthy cane or when picking the cane plant. Roots contact between soil and sugarcane plants or mutual friction between the leaves can spread the disease. The sugar cane juice was diluted to 10000 times the liquid and the ability to infect. The contaminated sugarcane knife was still infectious in the shadowy place for 7 days. The disease is more severe with the longer the perennial period.
(IV) Control measures Seedling disease is the main factor in the transmission of the disease. Therefore, the selection of disease-free seedlings and sterilization of seedlings are the main measures for preventing and treating the disease.
1. Heat treatment of seedlings There are three methods: 1 hot water treatment. Treatment with 50°C hot water for 2 hours can prevent this disease. This method should be treated with double sprouts as well as full-stem seedlings. The disadvantage of this method is that the sugarcane buds are easily damaged, affecting the germination rate. 2 hot air treatment. The tool for hot air treatment is a large electric heated blast oven. The temperature and time are 54-58°C for 8 hours. If 58°C is used, the control rate can reach 100%. The advantage of hot air is that the equipment is relatively simple, and it is not easy to damage the sprouts, so the germination rate is higher. Disadvantages are long processing time, time-consuming, labor-intensive, and highly susceptible to water loss. Therefore, all stem seedlings must be used for treatment, and they should not be split into two buds. 3 air steam treatment. After mixing with steam and air, enter the treatment tank so that the temperature in the tank is maintained at a constant temperature to treat the sugarcane plant. It is generally treated at 53°C or 54°C for 4 hours. This method eliminates the disadvantages of hot water treatment of vulnerable shoots and hot air treatment that takes time and is prone to losing water.
2. Establishment of a disease-free nursery. The heat-treated seedlings will be planted in a centralized manner and the cultivation tools will be disinfected to provide disease-free seedlings for large-scale production. The disinfection of the tool can be wiped with 70% alcohol, and it can also be sterilized by flame burning.
3. During the cutting process, the cutting cane knife and the tilling equipment must be separated from the operating tools of other varieties, used separately, often sterilized, and the field rodents should be promptly eliminated. After the rapid propagation of tissue culture without pathogenic stem apex meristem, a large number of virus-free healthy tissue culture seedlings can be obtained, and after the first and second seedling breeding, healthy stems can be obtained for field production.
4. Before the next kind of deep plowing, fine soil preparation, full base fertilizer. Fertilizer is applied in a timely manner to prevent drought, so that fruit cane enhances resistance to disease.
5. In order to prevent the heat treatment and the original health of the sugarcane species once again being infected by the ratoon dwarf disease, the sugarcane field must be completely cleared of sugar cane, all appliances such as cane knife, seed drill, etc. must be used before boiling, steam or fire Bake for disinfection.
6. Eliminate rodent pests from voles and other bite fruit cane to prevent the spread of germs.
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