| This paper takes Shandong area's Populus×euramericana cv. "74/76" and triploid Populus tomentosa in Gaotang Shandong as the object of study, carried on some experiments including surveying the occurrence and development situation of leaf spot disease, using spore capturing method to estimate emergence period of disease and proposal disease prevention time, studying the integrated control technique combined cultural methods and chemical prevention, detecting and evaluating the fast-growing performance and disease resistance of 29 introduced clones seedlings of P.deltoides and P. x euramericana in the field, to provide basic data for establishing the integrated control technology system. The main results are as follows:(1) Marssonina leaf spot occured seriously in stands of Populus x euramericana cv. "74/76". Late July is the initial period for the disease occurrence, started from mid-August the disease develop rapidly and aggravates gradually, peak appears in early September, then the massive leaves started to shed. Triploid Populus tomentosa leaf spot occurred in late July conditional on the temperature and rainfall, the disease developed rapidly, peaked in early September, then the leaves falling in profusion. Alternaria tenuis Nees. and Cercospora sp. was initially identified for the pathogen of this disease.(2) Through catching spores it was discovered that the number of spores captured have closely relationship with temperature, relative humidity and rainfall, particularly relative humidity and rainfall play the decisive role. Take spores discharge rule as basis to define the disease prevention time and frequency, suggested that chemical control to Marssonina leaf spot should start from mid-July, application continuously 3 times, and the interval of each time was 10d. Fungicides for controlling triploid Populus tomentosa leaf spot should be applicated for late July, early August and the mid-August after continuous rainfall, to prevent the A. tenuis initial infection can be implemented in mid-June with one time.(3) The inhibitory rates of 6 varieties fungicides to the leaf spot of M. brunnea and A. tenuis determined by measuring mycelium growth and counting spore germination. Selecting the best antifungal effect on pathogens of pharmaceutical concentrations in poplar field trial. The field trial results showed that the myclobutanil (2500 times diluted), myclobutanil (5000 times diluted), tebuconazole (2500 times diluted), difenoconazole (5000 times diluted) and mancozeb (500 times diluted) have the strong control action to Marssonina leaf spot, and the relative control effects were between 52.7%-75.3%. The difenoconazole (5000 times diluted), myclobutanil (2500 times diluted), mancozeb (500 times diluted) and difenoconazole (10000 times diluted) have certain degree control action to triploid Populus tomentosa leaf spot, the relative efficacy in 26%-48%.(4) The seedlings for afforestation should be selected for 1 year old with height of 3.5m, under the planting density for 2m x 2m and planting pit specification for 0.5m x 0.5m x 0.5m, quantity of growth for triploid Populus tomentosa was the bigest and the incidence of leaf spot disease was the lowest.(5) Determination and appraisal for the leaf disease resistance and the growth quantity of 29 P.deltoides and P.×euramericana clone seedlings, clone-01, clone-02, clone-599, clone-N-179, clone-Sangju, clone-82-130 and clone-82-133 were selected, compared with the local present major cultural variety P. x euramericana cv. "74/76", with faster growth rate, and stronger leaf disease resistance.
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