Research On Application Guidelines Of Cymoxanil·Mancozeb 72% WP To Control Phytophthora Blight On Ginseng

China is ginseng’s main production and export country, exports accounted for the world of 60% to 70%. Ginseng pesticide residues limits the exportation of ginseng to other countries. Cymoxanil+ mancozeb 72%(WP) is extensively used in controlling ginseng Phytophthora blight disease. In this thesis, research was carried out on the indoor toxicity, field experiments and the regularity of residual degradation and developed the use of the guidelines for the prevention and control of disease. Mainly achieved the following results:1. Mycelium growth rate method for determination of cymoxanil and mancozeb in different ratio of ginseng(Phytophthora cactorum) toxicity and formulation screening. the results showed that cymoxanil and mancozeb can be mixed, different ratio showed obvious synergistic effects which has a higher antibacterial activity with EC50 values from 0.54 to 2.17 mg/L. The EC50 value is lowest of 0.54 mg/L at 2:7 ratio of cymoxanil and mancozeb.2. Ginseng blight field test results show that cymoxanil and mancozeb wettable powder(72%) in the test dose of 648~1836 ga.i. /hm2 had better control effect of 59.14%~88.72%.3. A method to detect cymoxanil in the ginseng was established with high performance liquid chromatography tandem mass spectrometry(HPLC/MS/MS) and headspace gas liquid chromatography mancozeb(HS- GLC) was used to detect mancozeb residues in the ginseng. Based on the external standard method, the average recovery were 86.19% ~ 86.19% at adding different mass fraction of cymoxanil, relative standard deviation were 1.52% ~ 8.84%, and the correlation coefficient r = 0.9999, the average recovery of mancozeb were 81.30% ~ 81.30%, relative standard deviation were 1.18% ~ 4.19%, and the correlation coefficient r = 0.9838, this method was suitable for the residue quantitative analysis of residue detects of cymoxanil and mancozeb.4. The half-lives of cymoxanil and mancozeb were 6.3~10.7 days and 10.9 ~16.0 days at spraying dosage of 2754 g a.i. /hm2 of cymoxanil·mancozeb 72% WP, and these fingicides are easily degradate. At the dosages of 1836 and 2754 g a.i. /hm2 spraying 1 and 2 times in growing season and applying pesticide interval of 7 days, the interval to harvest were 14, 45 and 75 d,the final residues of cymoxanil were below 0.854 mg/kg in ginseng stem and leaf, below 0.033 mg/kg in soil, below 0.01 mg/kg in fresh and dry root. The final residues of mancozeb were below 3.61 mg/kg in giseng stem and leaf, below 3.42 mg/kg in soil, below 1.66 mg/kg in fresh and dry root.5. According to residue detect results on ginseng, recommended maximum residue limits(MRLs) of cymoxanil is suggested to be 0.1 mg/kg temporarily and mancozeb is 2.5 mg/kg temporarily, respectively. Based on the principle of risk assessment, mancozeb and cymoxanil percentage of theory exposed total amount accounting for permitted intake are 59.30% and 35.32% less than 100%, it Showed that the MRLs of cymoxanil and mancozeb for our country consumer is low risk, and are close to those of CAC and other countries, is helpful to improve the quality and safety of ginseng products in our country and the competitiveness of international trade.It suggested that cymoxanil·mancozeb 72% WP is used to control ginseng Phytophthora blight,the dosages were 648~ 1836 g a.i. /hm2 and application 1 times preharvestinterval was 14 days at the early time of the disease in a growing season.