Infection And Epidemiology Of Shoot Blight Of Pinus Sylvestris Var.mongolica

The infection and epidemiology of shoot blight of pinus sylvestris are studied by the forest pathology principle and by the methods of tissue separation, in and out chamber inoculation experiment, catching spore and sequent observation of disease state index on fixed sample area and so on, ultimately, we provide theory base for erncient control of this disease. Shoot blight of pinus sylvestris is a kind of host major disease. Isolates of sphaeropsis sapinea infect and survive in leaves, buds, branches, first year seed cones and many year seed cones on health and disease pinus sylvestris, which can lurk and communicate. However, the seeds of pinus sylvestris can抰 spread this disease because they don抰 carry disease. First infection source of disease is mainly spore, spreading by wind and rain, which flew off from the leaves and branch of the disease pinus sylvestris on last year, moreover it can communicate the same year burgeon, leaf and stoma; but it can抰 infect the old tissue when injecting without wound. Latent growth phase of isolates is 7-13 days; Idiophase of isolates is 23-28 days. Temperature rang of the Isolates of sphaeropsis sapinea is $-35C when it bourgeon, grow best on the condition of 25 揅 and 100% relative humidity; it can produce spore and spore apparatus under the condition of PDA substrate, astigmatism and normal temperature. Spore is dispersed at beginning of May, start to infect on the middle and last ten-day of June, reach the maximum of infection on the last ten-day of July and the middle ten-day of August and stop infection on the middle ten-day of September. Short term forecast model of disease development and wood loss rate are built. Control guideline and economic threshold value are decided.