With the aim to improve the level of monitoring and warning as well as the comprehensive control of rice blast disease, and to feasibly reduce the disease threat in Nanchong City, the methods of GPS and GIS, systematical monitoring and field survey, rice blast resistance identification, physiologic races of rice blast monitoring, and meteorological data analysis were performed to study the occurrence and epidemic region division, precise demarcation and occurrence and epidemic regularity of rice blast in Nanchong City. This study first completed the epidemic region division and precise demarcation; first clarified the initial affection（beginning period） locations, occurrence characteristics, epidemic trends and characteristics; explicated the existence of four epidemic peak periods of rice blast in the field, where the damage areas of first peak period played a decisive role during the blast epidemic years; in late May, the cumulative occurrence areas and annual occurrence areas presented higher positive correlation with the correlation coefficient of 0.817;and established a prediction model of occurrence areas per year based on the disease field rate at the end of boot stages and the diseased plant rate at dough stages. The results of investigation on the impact factors investigation of blast disease in Nanchong in recent years suggested that the internal causes were the decrease or loss of blast resistance of the rice cultivars, as well as the increase of physiological races with strong resistance to rice blast and the emergence of new virulent physiologic varieties; the external causes were suitable temperature, too much rainy, and sunlight shortage. Between 2010 and 2015, the short-term forecast accuracy for rice blast in Nanchong was up to 100%, and medium-and long-term forecast accuracy was also up to 98% and 95%, respectively, which increased by 5-15% than that before 1997, thereby making the control effect of rice blast in Nanchong increased by 15-30%.
The study was conducted to reduce blast damage, the use of pesticides residue, environment pollution and control costs, and to make a significant contribution to the improvement of grain production, quality and agriculture ecological environment. Over these years, by the methods of systematical monitoring, regular surveys, field investigation, rice blast resistance identification, experiments and meteorological data analysis, the study on comprehensive prevention and control of rice blast in Nanchong City was conducted. The results showed that the rice varieties more sensitive to blast had a higher incidence of severe blast disease. Replacing,varieties with different source of resistance every three to five years and reasonable variety distribution can effectively reduce the prevalence of rice blast. Appropriate treatment of infected rice straw and pathogen, seed disinfection, seedling disinfection, and pesticide application at transplanting and etc. can delay blast occurrence and reduce the damage caused by blast. By analyzing the blast control efficiency of pesticides applied at different growth stages, we found that best control efficiency against blast was achieved by spraying pesticide twice during the whole growth stage, once 3 d before transplanting or 10 d after transplanting; and once at initial heading stage. Spraying 525 g/hm^2 75% tricyclazole was proven to be the best dosage for blast control. However, 375-450 g/hm^2 75% tricyclazole is enough if the blast incidence is not severe, or the rice varieties are slightly susceptible to blast.The control efficiency against leaf blast between 4% kasugamycin and 20% tricyclazole had no significant difference, but was significantly higher than that of 100 billion spores/g of Bacillus subtilis. The control efficiency against neck blast had no significant difference among 4% kasugamycin, 20% tricyclazole and 100 billion spores/g of B. subtilis. 450 g/hm^2 75% tricyclazole had better control efficiency against neck blast than 2 250 g/hm^2 2% 800 million spores/g
In order to promote ＂green plant protection＂, reduce the administration dosage and residue of pesticides and control cost of environment pollution, and improve maize production, quality and agricultural ecological environment safety. In this study, the control effect and benefit of bio-guide wasp virus missile（BGWVM） on Ostrinia furnacalis in Nanchong City was investigated by using insect light traps and combined method of field investigation and experimental demonstration. According to the results, applying 30-37 pairs of BGWVM per hectare exhibited an average control efficiency of 78.0%, and the control cost was 139.50-172.50 CNY/hm2, which was reduced by 142.50-168.00 CNY/hm^2 compared with conventional chemical control. Average maize yield in BGWVM demonstration plot was 817.8 kg/hm2 higher and improved by 11.0% compared with blank control plot. The output value was improved by 1 799.16 CNY/hm^2 and the revenue increased by 1 941.66-1 967.16CNY/hm2. During 2003-2014, the cumulative demonstration and popularization area of BGWVM technique in Nanchong City had reached 24 507.33 hm^2, and the cumulative yield increment reached 20.042 1 million kg. BGWVM application improved total output value by 44.092 6 million CNY and saved control cost by 3.492 3-4.117 2 million CNY, thus increasing the revenue by 47.584 9-48.209 8 million CNY. BGWVM application reduced 551.41 t of 5% dimehypo GG or 12.87 t of 90%monosultap WP. In addition, BGWVM technique is simple to use, labor-saving and safe for human, animals, environment and crops, with significant economic, ecological and social benefits and without any side effect, which has become an ideal substitute for controlling O. furnacalis and reducing chemical pesticides in organic agriculture industry, modern agriculture industry, production of green and pollution-free agricultural products and IBM prevention and control demonstration gardens.
