Foshan Ja Suo Medical Device Co., LTD , https://www.fjoralinstrument.com
Second, the incidence of law. Mycelia and immature fruiting bodies are wintered in diseased tissues. The occurrence of conidiospores and mature conidia in overwintering lesions became the main source of infection in the year. The onset began in April of the following year, and the first peak of onset occurred from late May to June. In July and August, when the temperature increased, the disease was slowed down, and the second peak appeared on the month. At this time, the germs originated from the conidiospores formed in the spring of the year and stopped after October. The temperature in spring is above 10°C, and when the relative humidity is above 60%, the disease begins to occur; at 24-28°C, it is the most suitable disease. Pathogens enter from wounds or lenticels, and the incubation period is approximately 1 month. It takes 2-3 months from the onset to the formation of the conidial phase, and cysts and ascospores form in the lesions in the fall. Latent infection is an important feature of poplar canker disease. When the tree vigor is weak, it is conducive to disease. The lesions that developed on robust trees that year were able to heal naturally in the following year. The same disease tree, Yang surface lesions more than the dark side. Untransplanted seedlings are generally not affected or lightly diseased. Once transplanted, the water loses its balance, the tree vigor is weakened, and the disease easily occurs. The peak incidence in spring is the result of the infection in the fall of the previous year, not the spring of the year. During spring afforestation, new lesions on the initial planting young forest were also the result of infection in the nursery the first year. Therefore, the number of bacteria in seedlings is closely related to the incidence of saplings in new forest lands. Drought-inducing site conditions are an important cause of morbidity, and are also the main reasons for the particularly prevalent and serious ulcer disease in the “Three North†areas of drought and semi-arid in China. The large number of seedlings at the time of raising seedlings and the loss of water in seedlings during afforestation are the intrinsic causes of the initial saplings being susceptible to disease. Different species and strains of poplars have significant differences in resistance to canker disease. Poplar trees are resistant to disease, and black poplar tree species are moderately resistant, while poplar tree species are more susceptible. The vast majority of hybrid strains of the Qingyang School and the Heiyang School are also susceptible to disease. Qing Yang, Xiao Qing Yang, Yang Yang and Beijing Yang are all highly susceptible poplar trees. Among the factions that are resistant to disease, some strains are susceptible, such as Populus tomentosa is a more resistant tree species, and some of them (triploid Chinese white poplar) are very susceptible. There are also disease-resistant strains in susceptible types. At the same time, the susceptibility of tree species is closely related to the environmental conditions in which they are located.
Third, prevention and treatment methods.
1. Use disease-resistant factions or varieties; do not transfer seedlings from wards or disease gardens.
2. Suitable land suitable tree. Before planting trees, tree species should be selected according to the probability of occurrence of ulcer disease at the planting site. Drought and infertile soil sections are areas with high incidence of disease, avoiding afforestation with diseased tree species, and doing a variety of prevention and control preparations.
3. Clear diseased trees around the nursery to reduce the source of infection.
4. Strengthen seedling management. Raising seedlings, planting to protect the roots; reducing seedling transport time to reduce seedling water loss; in conditions where the seedlings emerge, immediately immersed in water for 24 hours, in order to facilitate the maintenance of bark moisture content; spraying the roots before planting The growth promoters such as 2,4-D are beneficial to the growth of new roots, increase water absorption and reduce disease; they should be watered immediately after planting.
5. In the sand afforestation, if it can cover 1mx1m plastic film at the root of the sapling, it is very beneficial to the maintenance of soil moisture and increase the temperature of the soil, and accelerate the growth of new roots, thereby increasing the water content of the bark. The addition of water-absorbing agents to the soil and other measures that are beneficial to the maintenance of soil moisture have the effect of reducing disease in young trees under drought conditions.
6. In some parts of northern China, autumn afforestation is beneficial to the restoration of poplar roots and early spring rooting, which has the effect of reducing disease.
7. Chemical control: (1) Strengthen the management of seedlings cultivation. In the fall (early September), seedlings that are to be planted in the coming year should be sprayed once with 70% thiophanate-methyl 200 times to reduce the amount of seedlings attached to seedlings; (2) Before planting seedlings ( Or colonized, but need to spray or dry with 70% thiophanate-methyl 100-fold (or 2.12% of 843 rehabilitative agent 100 times, bacteria-purified 300-fold solution) before the onset of the peak, that is, in early April.) .
Poplar fungal canker
First, the symptoms. The disease is harmful to the branches of poplars, and the incidence of saplings that have just been transplanted is the most important. There are two types of lesions, a blister type: This is the most common symptom of the disease, usually with watery lesions mainly round or oval, about 1cm in diameter, the edge is not obvious, hand pressure lesions are brown The liquid flowed out, and the later lesions subsided, appearing gray-brown, with cracks in the center. Leech type lesions only occur on the light-leaved poplar, forming blister at the edge of the lenticels, which is initially round and minimal; after the blister becomes larger, the diameter is O.5-2.Ocm, and the enamel is filled with pale brown liquid; Afterwards, the blister burst and the pale brown liquid flowed out. The air turned dark brown, and the lesion was dyed dark brown. Finally, the lesions collapsed and subsided, and there was a longitudinal crack in the center. 2 The spotted type: Water spots on the bark a few millimeters round spot, slightly raised, hand pressure with a moist feeling, after the dry shrinkage into a micro-sag round spot, dark brown. In the lesions that appeared in the spring, many black dots were produced from late May to early June, which are the conidia of pathogens. Fall formed lesions, conidia often form in the next year. The subcutaneous lesions become brown and necrotic. The disease mainly occurs in the middle and lower parts of the trunk, and when severe, it spreads to the upper part of the trunk and branches. The most serious victims are newly planted saplings. The rate of diseased plants is not only high, but also the proportion of total surface area of ​​lesions in dry surface area. '