Eucalyptus tuberculosis is caused by Agrobacterium tumefaciens, which occurs mainly in trunks, shoots, and even roots. Although the eucalyptus with tumor does not necessarily die, if it occurs in the seedlings, dwarfing and stunting may occur. The symptoms often occur accompanied by the loss of light from the leaves, and even worse, it will die, resulting in reduced quantity and economic losses. . If it occurs in the large banyan tree, it will not cause the symptoms such as stunting, but it will often cause the tree vigor to weaken, and it will easily cause the invasion of other tree pests and diseases.
The host range of eucalyptus root-noddle germs is quite extensive, and at least 138 families, 588 genera, and 1,193 or more plants can be infected. The plant is mainly composed of dicotyledonous plants in infected angiosperms, but it also infects small numbers of monocotyledons and gymnosperms in angiosperms. Among the more economically important hosts are peaches, pears, apples, apricots, grapes and other fruit trees, chrysanthemums, roses and other ornamental crops, as well as pine, birch, aspen and other forest plants.
Rhizoma is a soil-transmitted disease. Pathogens can survive in the soil especially near the root circle for several years. When the host plant has a wound, the pathogen can invade the infection and cause disease. Pathogens can be spread by irrigation water or rainwater. They can also be spread by grafting, pruning and weeding, transplanting, agricultural tools contact, and insect feeding. Because the pathogens are invaded by wounds, the prevention of wounds is the main preventive measure. The cancerous bacteria can also remain in the soil and invade through the wound in the plant's rhizome. The tumors produced in the early stages are smoother and softer, and are easily attacked by insects or saprophytic bacteria, causing secondary infections, while the aged tumors become lignified and hard.
If this disease occurs in the nursery, it can be transported by seedlings and then transmitted to other parts of the disease. A few years ago, there was a case in which the tree seedlings were infected with tree cancer and the disease was transmitted to other sites. The burning of the burning process was carried out, but a considerable amount of national resources have been wasted. There are many factors that cause tumors. To avoid misdiagnosis, the samples need to be separated by tissue, and pathogen-free strains are easily isolated in the soil or rickets. Therefore, the isolated bacteria must be tested for pathogenicity, and bacteria can be cultured. Apply directly to the carrot cuts, or inoculate on the petiole or stem of the tomato by acupuncture, or inoculate on plants such as rooting roots, and judge whether or not a tumor has developed.
Control methods:
The disease is mainly prevention. Prevention of eucalyptus root nodule disease is mainly due to careful purchase when purchasing seedlings, avoiding wounds in the stems before and after planting, especially in areas close to the soil. In addition, it is not appropriate to use soil cover soil near the susceptible strain to avoid infection. Since the root-disease-infected plants are difficult to treat afterwards, it is best to find that the diseased plants must be immediately removed and burned, and the soil disinfectant should be used to disinfect the planting holes before planting.
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