| The forage diseases were significantly affected by management strategies such as grazing which is the main utilization mode of grassland and burning. In order to reveal the effects of these two managements on forage diseases in Northeast, the forage diseases were surveyed in grassland with different grazing intensities and late spring burning at the experimental station of Northemeast Normal University in Changling county, Jilin Province during the growing season of two consecutive years, 2013 and 2014. The major results are as follows:1. There were 10 genus,12 species pathogenic fungi cause of 19 diseases in 11 species of plants. The most common diseases were powdery mildew and rust which cause diseases in 6 and 3 plant species, respectively. The popular plants associated with these common diseases were Gramineae, Leguminosae, Polygonaceae, Compositae which had 10,4,4, and 1 kinds of diseases, respectively. The most popular diseases were spot disease (Ascochyta sp.) and leaf spot disease (Phyllosticta sp.) in Leymus chinensis this studied area.2. Eleven forage diseases were preliminary identified as the new disease records in Jilin Province which included Phyllachora graminis of Chloris virgata, Exserohilum sp. and Septoria sp. of Phragmites australis, Oidium sp. of Aeluropus litthoralis, Uromyces sp. of Calamagrostis epigeios, Uromyces sp., Phyllachora sp. and Ascochyta sp. of L. chinensis, Botrytis cinerea of Sonchus brachyotus, Oidium sp. and Puccinia Persoon of Kalimeris integrifolia.3. The diseases were influenced by grazing intensity which included 0,3,6 sheep/hm2. The disease incidences and severity of leaf spot of L. chinensis caused by Ascohyta sp., Phyllachora sp. and Physoderma sp. were the highest under 3 sheep/hm2 treatment and the lowest under 6 sheep/hm2 treatment. While the disease incidence and severity of Uromyces sp. of L. chinensis decreased with the increasing of grazing intensity.4. The treatment with burning significantly reduced the disease incidence, severity, the number of forage diseases and changed the period of diseases. There were 4 families of host plants including Polygonaceae, Compositae, Gramineae, and Leguminosae associated with diseases without burning whereas there was only Gramineae family of host plants associated with diseases with burning. There were only 5 species of diseases including Ascohyta sp. and Phyllachora sp. of L. chinensis, Puccinia Persoon and Septoria sp.of Phragmites australis, Uromyces sp. of Calamagrostis epigeios with burning although there were 17 species of diseases without burning. The disease incidence of these 5 species decreased from 39.0%-58.0%,20.0%-36.0%,10.0%-55.0%,20.0%-65.0% and 8.5%-30.0% to 9.7%-35.9%,4.0%-21.7%,0.0%-36.0%,0.0%-30.0% and 0.0%-20.0%, respectively. The severity of these 5 species decreased from 17.3-40.7,9.3-21.7,3.3-28.3,6.7-31.7 and 3.3-11.7 to 4.0-27.5,1.6-11.8,0.0-20.7,0.0-11.7 and 0.0-7.3, respectively. Furthermore, burning significantly reduced the incidence and severity of diseases in June, July, and August, however, it did not affect these two indices in September and October. With burning, the peak period of all the 5 diseases incidence delayed from August to September and the initial period of other three diseases excepted with Ascohyta sp. and Phyllachora sp. of L. chinensis delayed from June to July.5、Combined with both grazing and burning treatments, the incidence and severity of spot diseases of L. chinensis caused by Ascohyta sp. and Phyllachora sp., the rust and leafspot of Phragmites australis caused by Puccinia Persoon and Exserohilum sp., and the rust of Calamagrostis epigeios caused by Uromyces sp. were the highest under 3 sheep/hm2 treatment and the lowest under 6 sheep/hm2 treatment. The peak period of all the diseases were September. The initial period of other three diseases excepted with Ascohyta sp. and Phyllachora sp. of L. chinensis were July. |
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