Study On The Survey And Chemical Control Of Weeds In Wheat Field In Hebei Province

The development of wheat industry has a great effect on the food security and social stability of the country. Every year the wheat acreage is about 24590000 hm2 around all the nation, and Hebei is one of the major wheat producing province, so the production and development of wheat is the priority among priorities of Hebei agricultural work.1. The results of weeds investigation in wheat fields of Hebei Province in 2013 and 2014 years showed that 57 weed species,which belonged to 22 familes, existed in the wheat fields of Hebei province. Among these species,10, 38, 7,and 5 weed species were considered as normal weeds and common weeds, regional dominat weeds, dominant weeds, respectively. The overall abundance of Descurainia sophia, Capsella bursa-pastoris,Chenopodium album L.,Convolvulus arvensis L. and Bromus japonicus Thunb. ex Murr..2. The results of seed bank of Handan, Xingtai, Shijiazhuang, Baoding, Qinhuangdao, Langfang in Hebei province showed that, D. sophia’s seeds mostly existed in depth the surface of 0~5 cm, and the seeds number decreased gradually along with the depth deepening.3. The toxicity determination of the single herbicides to D.Sophia showed that due to large-scale excessive using to Bensulfuron-methyl, 2-methyl-4-chlorophenoxy and Tribenuron-methyl to control D.Sophia long-term, the D.Sophia appeared very strong resistance to the above agents, the IC50 values of them were as high as 213.2 mg/L, 107.2 mg/L and 553.3 mg/L, it follows that the toxicity of them is general; but Carfentrazone-ethyl, Fluroxypyr and Florasulam had a great control to the development to D.Sophia, and IC50 alues were 8.7 mg/L, 49.8 mg/L and 41.5 mg/L, respectively.4. The evaluation of combination toxicity of different herbicides indicated that when the ratio of bensulfuron methyl, fluroxypyr, florasulam with carfentrazone-ethyl was 3.33:1~5:1, 6.67:1~8.33:1 and 2:1~3:1 respectively, the joint effect of them was additional; and when 2-methyl-4-chlorophenoxy compounded with carfentrazone-ethyl and only the ratio was 18.33:1, the joint effect was additional; but the joint effect of florasulam compounded with fluroxypyr was all additional under the test ratio. Therefore, when the agent above compounded each other, we can choose the above proportion, and try to choose a reasonable distribution plan, in case of the resistant.5. According to result of the inhibition rate and IC50 of the compound agents to D. Sophia, IC50 value of 6% florasulam · carfentrazone ethyl was 4.20 mg/L, significantly lower than the florasulam’s 49.80 mg/L and carfentrazone ethyl’s 8.7 mg/L, and it was consistent with its the joint effect; the IC50 value of 34% carfentrazone ethyl · fluroxypyr is 22.9 mg/L, significantly lower than the fluroxypyr, but higher than the carfentrazone ethyl; IC50 value of 37% Bensulfuron methyl · carfentrazone ethyl · Clodinafop propargyl is 168.60 mg/L, indicated that carfentrazone ethyl compounded with Bensulfuron methyl can enhanced the reagent herbicidal activity, reduced the resistance to the D.Sophia; similarly, because of existence of carfentrazone ethyl, the IC50 value turned into 43.20 mg/L; and the effect of tribenuron methyl compounded with silicone additives was more significant, the IC50 alue increased by about 5 times than single use.6. The field research showed that the results of single herbicides field efficacy trials were consistent with indoor toxicity test results, the control effect of carfentrazone-ethy, fluroxypyr and florasulam was significantly greater than tribenuron-methyl; in addition all the jointed herbicides had an outstanding effect on D.Sophia, could significantly inhibit the growth of D.Sophia, and faster than single herbicides, especially37% bensulfuron methyl?carfentrazone ethyl · clodinafop propargyl, 70.5% 2 a 4 sodium chloride · carfentrazone ethyl, 34% carfentrazone ethyl · fluroxypyr and 6% florasulam · carfentrazone ethyl, whose control effect can reach up to 90% after treatment 28 d, and have further popularize meaning to use largely; moreover tribenuron methyl and 2 a 4 sodium chloride that strains and weight control effect only half for other processing had a bad control effect on D.Sophia. Whereas, when tribenuron methyl and silicone additives applied at the same time, it was found that its strains and weight control effect had no difference to the jointed herbicides, thus it can be seen tribenuron methyl compounded with silicone additives can gain a better effect on D.Sophia.7. The P. aeruginosa granula biological activity assay showed that it could have a good inhibition effect to D.Sophia, which can reach up to 90%, and it’s safety to wheat, moreover it can keep activity about 30 d at the temperature-80℃. The secondary metabolites of the strain contained active herbicidal compounds in the retention time of 5.923 min by purification.