| The yields of wheat and maize, the main grain crops in Hebei province, are restricted by bio-disaster risk for a long time. In recent years, the new changes of diseases, insect pests and weeds of wheat and maize have caused by the changes of production conditions including climatic conditions, tillage management, cultivar variations, water and fertilizer management and cross-operating of combine harvesters, meanwhile, which increased the risk of the food security production. At present, the bio-disaster management of winter wheat and maize is mainly crisis management but not risk management in Hebei Province. The prevention and treatment of diseases, insect pests and weeds of wheat and maize were developed gradually and very little effects with a high investment. Under the new production condition, it is an important measure to enhance the research in bio-disaster risk management of wheat and maize for carrying out the plant protection principle of“prevention-first and combination with control”, which is also an important guarantee for reducing possibly the yield loss of wheat and maize, the food security production and the sustainable development.In this paper, the bio-disaster situations of wheat and maize, in 32 monitoring sites from the three different ecotypes, Piedmont, Heilonggang and Eastern Plains in Heibei Province from 2000 to 2010, were analysised by the methods of documentary research and quantitative and qualitative analysis. The meteorological data of Gu’an, Qingyuan and Quzhou counties was analysised from 1981 to 2010. The situation of harvester application and the degree of cognition and implementation to the bio-disaster risk management were analysised by investigating the plant protection department workers of the nineteen counties to clear the occurrence of the diseases, insect pests and weeds, the effects of the changes of production conditions and the present situation and problems of bio-disaster risk management in Hebei province. In the last, the background, recognition and analysis of the bio-disaster in accordance with the process of risk management were cleared, and then the bio-disaster risk evaluation index system of wheat and maize was established by the method of PRA multiple indexes synthetic analysis for pest risk. The basic scheme for handling risk was raised by setting the calculation formula of risk value. The results are as follows:The main species of diseases, pests and weeds had reached up to 15, 20 and 21 respectively in Hebei province. The main diseases and pests were Powdery Mildew, Sharp Eyespot, Scab, Aphids, Wheat-spider and Wheat midge with Descurainia Sophia as the dominant species in all weeds. There were four characteristics about the occurrence of the diseases, insect pests and weeds, including some secondary diseases and insect pests becoming to the dominant, the complex and diverse weeds species, a tendency expanding from the former location to North and East and a continuous damage to wheat and maize. The pest species of maize increased significantly with some diseases and pests, for example, the northern and southern left blight, seedling blight, root rot, brown spot, ear rot, corn borer, thrips, soil insects, armyworm and so on. Rough dwarf disease began to be popular in some regions even with no production. At the same time, the top rot disease and the proxenus lepigone took place in a large area as the new disease and pest.The bio-disasters of wheat and maize were affected significantly by the changes of the production conditions in Hebei province. Since 1981 to 2010, the average temperature has an increasing trend in Hebei province with a decreased negative accumulated temperature year by year. The precipitation and the relative humidity also decreased. There is a positive correlation between the changes of precipitation and relative humidity with the disease area of scab, powdery mildew and leaf spot, but no correlation with the area of insect pests. Aphids of wheat and corn borer were affected significantly by the increasing annual average temperature, but no effect on the other insect pests and diseases. The reduction of negative accumulated temperature could increase the over wintering basic number of pathogen, eggs of insect pests and weed seeds. The occurrence and joint damage extents of the diseases and insect pests were aggravated by the no-tillage planting and straw returning. It is very easy that wheat and maize were infected by a variety of pathogen and insect pests because of the single resistance and the wrong management of water and fertilizer. For example, the high occurrence area of Sharp Eyespot was caused by the over application of nitrogen fertilizer. In some extent, the significant changes of variety, the new disease and insect pest and the obvious tendency expanding to north and east were caused by the cross-operations of combine harvesters, as the good media spreading the diseases and insect pests. In a word, the occurrences of bio-disasters were promoted by the changes of production conditions, and then the risk of food security production was aslo improved in Hebei province.At present, the bio-disaster management mostly depends on the crisis management in Hebei province, with the proportion of 95.6 percent, but the proportion of risk management is very poor. There are mainly four problems for bio-disaster risk management in Hebei province including lack of risk management knowledge, the low perceived importance of the government, lack of the legal and technical specification, investment, assessment staff and unreasonable investment structure.During the bio-disaster risk management process of wheat and maize, the bio-disaster risk assessment index system and evaluation standard were constructed according to the distribution, potential risk, production conditions, the possibility of spread and diffusion and difficulty of management. The risk calculation formula, R = (P1·P2·P3·P4·P5)1/5, was set, and the basic measures to handle the risk also were proposed. In this study, the scientific basis and technical reference were provided for bio-disaster risk assessment of wheat and maize in Hebei province. |
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