| Eupatorium adenophorum Spreng, a invasive weed, grow and spread in many parts of our country, has become malignant and developed into the weeds difficult to control. Eupatorium occupy grassland, harm livestock and result in reduce of the crops'production. The invasion of Eupatorium not only harms for agriculture, forestry and grassland farming, but also has serious repercussion on the ecological environment and biodiversity. Therefore, these theses on Eupatorium were studies as the following aspects:1,In the process of the invasion and expansion of Eupatorium adenophorum Spreng, the study of allelopathy has become a hotspot in China and abroad. We tested whether or not Eu. adenophorum secretions has allelopathy to four species of pasture, Lolium multiflorum Lam, L. perenne Linn, Medicago sativa Linn and Vicia satival L. The experiment was designed as follows: (1) Remove vigorous Eu. adenophorum before planting the pastures; (2) Plant the pastures in top 10cm soil layer in which Eu. adenophorum had grown or not grown; (3) Plant the pastures in pot and petri dish containing the liquid in which Eu. adenophorum had grown, respectively. The result of the experiment indicates that the germination rate, the height and the fresh weight of the four pastures in soil where croften weed had grown has no significant differences when compared to the control soil. The result of the potted plants that watered with the growth liquid or petri dish containing the same liquid, in which croften weed had grown previously, indicates that the survival rate, the height and the fresh weight of the pastures has no significant differences compared to water. It is, therefore, concluded that Eu. adenophorum Spreng has no obvious allelopathy to the four pastures.2,Screening better herbicides for controlling Eupatorium by the chemical method: In order to control effectively the spread of Eupatorium, slow toxicity and environmentally friendly herbicides were screened in the paper. Experiments on the six herbicide tested in field show that: benzyl methyl, nicosulfuron and pendimethalin may be effect on late stage of the controlling Eupatorium; triclopyr was used in area where Eupatorium was needed to eradicate immediately; Eupatorium can be retained while the seed can be reduced, even eliminated, when the low concentration of picloram and sulfometureon methyl were used, which can control the biomass and prevent it spread into the surrounding areas. At same time, there was an very good killing effect on Eupatorium when the high concentration of picloram and sulfometureon methyl were applied.3,The contact angle's changes with time was studied that of picloram solution and sulfometureon methyl solution contained different concentrations petroleum oil on Eupatorium adenophorum Spreng leaves. So the time when the drop and the leaves reached a state of equilibrium, that is the proper time of determining contact angle, was ascertained. Further, the contact angles were measured at the time determined before, and we can find the added petroleum oil's minimum concentration which is enough to enhance the solution's wetting property on the leaves while the contact angle is less relatively. Hope the results can provide some assistance to control and eliminate Eupatorium adenophorum Spreng. The conclusions can be drawn that the equilibrium time is 50 s. the better ones of the groups contained the herbicide and the petroleum oil are followed as: 0.2 g·L-1 picloram with 0.02% petroleum oil; 0.4 g·L-1 picloram with 0.04% petroleum oil; 0.8 g·L-1picloram with 0.004% petroleum oi; 1.6 g·L-1 picloram with 0.004% petroleum oil; 0.1 g·L-1 sulfometureon methyl with 0.02% petroleum oil; 0.2 g·L-1 sulfometureon methyl with 0.004% petroleum oil; 0.4 g·L-1 sulfometureon methyl with 0.04% petroleum oil; 0.8 g·L-1 sulfometureon methyl with 0.02% petroleum oil.4,When commercial formulations of picloram and sulfometureon methyl formulations were diluted to1250,2500,5000,10000 and 625,1250,2500,5000 times with the local water taken from the city of Xichang in Sichuan Province, the surface tension of both solutions of picloram solution and sulfometureon methyl were bigger than the critical surface tension of Eupatorium adenophorum Spreng. The contact angles of the picloram solution and sulfometureon methyl solution on Eupatorium adenophorum Spreng leaves were 50～70°after 4min contacted although the efficacies were satisfied for control of Eupatorium adenophorum Spreng with picloram and sulometureon methyl solution, but, the drops from the two solutions on the leaves were not easy to be reserved, which led to run off and environmental pollution. In order to reduce the contact angle and to improve the wetting of the two herbicides on Eupatorium adenophorum Spreng, the reasonable concentrations of silicone surfactant added to herbicides were studied. After three factors, e.g. the CMC of the silicon surfacan, the critical surface tension of Eupatorium adenophorum Spreng and the surface tension of the solutions added the different concentrations of the solicon, were tested, an initial conclusion could be summarized that when≧0.05% silicon was added to the solutions of two herbicides, the drops could be spreaded. The more silicon was added, the better witting was obtained.5,Dynamics degradation of picloram residue in soil was studied. The analytical method for residue and degradation dynamics of picloram in soil was established by C18 solid phase extraction column and HPLC. The results showed that: recovery ranged from 65.27% to 109% and variation coefficient ranged from 5.49% to 12.33%. The degradation of picloram in soil was conformed to the first-order dynamic equation; the relative coefficient was 0.9344; the half-life of picloram in soil was 31.65d.6,Residues in the soil in the different spray technology was studied: Today most of the pesticide spray machines run mainly by power and only a small part of the pesticide spray on plant surface. Generally the utility of the pesticide sprayed was only 20% to 30%, that is, most of the liquid is scattered and flowed to the ground. The ability of the adhesion of the liquid on the leaves is an important part of the sprayed technology. In the conventional spray conditions, excessive moisture distribution capacity led to great loss of liquid, while the small contact angle make liquid roll easily from leaf, whose two cases would reduce the efficiency of pesticide distribution. The main way to resolve this contradiction is to improve the spray techniques. It was tested that the residue in the soil was caused in the conventional spray, the electrostatic spray and the ultra low volume spray technique. The result showed residues in soil by electrostatic spraying is least, that is, utility is the highest.7,Exploring absorption and conduction law of picloram in the plant of Eupatorium: In recent years, articles on picloram residual determination are few. There is little the relevant research report on the picloram's residue and conduction distribution in Eupatorium. It is a certain significance to find fast and efficient method to determinate picloram residues for the prevention and Eupatorium and the determination of the residues in other plant. Conclusion through experiments: picloram was absorped by the top of Eupatorium, and transmitted to the roots of the plant. To save pesticides and reduce environmental pollution, the method of smearing directly picloram on the top of Eupatorium can be uesd.
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