In the spring of poplar, it is often seen that the trees are covered with yellow powder piles and are shaped like the malformed buds of yellow hydrangea. The severely infested disease shoots dry after about 3 weeks, which is poplar rust. After the leaves exhibited by the normal buds were invaded, small yellow spots were formed. Afterwards, scattered yellow powder piles were seen on the back of the leaves, that is, the urease spores of rust pathogens. Severe summer spores can be combined into large blocks, and the back of the bacteria uplift. Invaded leaves will advance defoliation. In severe cases, large patches will form and even leaves will die. Colder early spring can be seen in the diseased leaves on the pods near-round or polygonal pods, that is, the teliospore of rust pathogens. The bacteria will also harm the young shoots and form ulcers. The pathogenic bacteria that cause poplar rust in our country are horse ray ray bacterium, poplar bacterium, and schizophora spores. It is generally recognized that the first two are in our country. There was no significant difference in the morphology and size of the two spores between urediospore and teliospores and lateral filaments. The summer spores are yellow, scattered or aggregated. The teliospores are orange, round or elliptic and have thorns on the surface. Side filaments are head-shaped or spoon-shaped. Light yellow or colorless. The teliospores piled under the epidermis of the host, and the teliospores were nearly cylindrical. The above pathogens can live in winter buds in the state of mycelia. With the increase of temperature in spring, winter buds begin to move, and the hyphae that have passed through winter begin to develop gradually and form the uredia spores heap. Infested winter buds cannot grow leaves and form embroidered spheroids that cover the spores. These diseased sprouts become the center of the field's initial infestation. The mycelium in the dry tip can also overwinter. Although the winter spores on diseased leaves have the ability to sprout and infect after winter, their germination power is rapidly lost as the temperature rises in summer. Therefore, the role of primary spores in the initial infection is far less important than the sick winter buds. In natural conditions, although teliospores are also formed, the number is not large, so it can be confirmed from the actual conditions in the field that teliospores have no important role in infection. In the coastal areas of northern Jiangsu, the disease buds have gradually emerged when the temperature rose to 15-16°C at the end of March and early April. General disease buds begin 1-2 days earlier than Jian buds and dry after about 3 weeks. The disease buds are mainly in the upper part of the dry bar. The period of emergence of pathogenic germs is about 4 weeks, but it mainly occurs in the middle or late April. Due to the repeated infestation of summer spores, the peak period of onset was May and June. By July and August, as the temperature keeps rising, it is not conducive to the germination and infection of the uredia spores, so the disease enters into a gentle period. At the beginning of September, the temperature gradually decreased. With the secondary extraction of the foliage, the disease entered the development stage again, forming the second peak period of disease. By the end of October, the disease would cease to occur due to the continuous decrease of temperature. In the early spring, the emergence of disease buds can be detected and removed in a timely manner using the characteristics of the diseased buds with bright colors and special shapes. The removal of diseased germs should be early and thorough, and should be followed by packing into plastic bags in order to prevent the spores from spreading. It is also possible to spray carbendazim 800 times solution to eradicate the diseased buds, if supplemented with the removal of disease buds or sprays. Drug measures can effectively control the occurrence of diseases. During the onset of the disease, spraying 50% of dexanamone 100 times solution or 50% trehalose 500-1000 times solution has a certain effect. Laboratory tests showed that the detergent powder had a 100% inhibition of spore germination at 2000 times. Remove defoliation of field bacteria in time to reduce the possible source of germs. Since most of the summer spores fall within 300 meters from where they are produced, the nursery area should be as far away as possible from the large seedling area of ​​the pathogen.
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