Studies On Damage Investigation And Chemical Control Of Soybean Weeds In The North Of Heilongjiang Province

In the north of Heilongjiang Province, soybean is the primary crop. Due to the large total and percapita arable land, extensive management and other problems, the weed species are of many kinds andlarge in quantities, which lead to harm seriously,in addition to the herbicide uses blindly andunreasonably. To solve these problems, more effective and targeted should be measured to controlweeds in soybean fields, in this study we have investigated weed species and occurrence dynamic in theregion, then get the formula of soybean yield loss effects of different types of weeds through the weedshazard loss test, finally by comparing10kinds of common low residual herbicides,we elect applicableherbicide suitable for the actual production of soybean in the region, to help farmers select theappropriate low residual herbicides to improve control effect. The main contents and results of thispaper are as follows:(1) The survey of the weed species results show that there are a total of17families,33speciesweeds in soybean fields in the region, including27kinds of broadleaf weeds accounted for81.8%,5kinds of poaceae weeds accounted for15.1%.25kinds of annual weeds (75.8%),8kinds of perennialweeds (24.2%).9families and12species of weeds have relative abundance more than10, among whichthe frequency of Barnyardgrass reaches100%. The abundance species of broadleaf weeds and thehigh relative abundance and frequency of occurrence of Barnyardgrass make it difficult to prevent insoybean fields.(2)The occurrence of weeds dynamic rendering logistic curve model.At around10ds after soybeansowing weeds begin to seedling, weed emergence after sowing24ds reaches the peak, and theoccurrence of a total of42ds, among which Barnyardgrass and Commelina accounting for the highestone-day germination rate and average density. By the end of the survey, the average density of weedshas been271plants/m2. Weed emergence is concentrated, explosive, and peak of weeds occurrence isbasically synchronized with the peak of soybean emergence in soybean fields. The concentration ofweed emergence and large population density has caused great difficulties to chemical weed control.(3)Regardless of whether they are completely gramineous weed communities or broadleaf weedcommunity relative to all kinds of weed populations of mixed community has obvious advantages. TheMixture of different types of weeds influence quite large on soybean yield, cut the rate reaching to71.50%-90.44%, weeds influence on soybean yield from strong to weak (high to low crop productionrate) order: mixed weed natural growth area>poaceae weeds grow naturally district> broadleaf weedsnatural growth area.(4)In the10selected test chemical herbicides, four kinds of soil-applied herbicide are recommenedto use50%flumioxazin WP on annual and perennial broadleaf weeds to control processing, using96%of the s-metolachlor EC on annual poaceae weeds to control processing; for the six kinds offoliar-applied herbicide are recommended to use84%of the cloransulam-methyl WDG to controlbroadleaf weeds, such as large weed plants a tag of48%bentazone AS are recommended. And in the control of poaceae weeds, all the three kinds of weeds herbicides can be used.In this study we have invested the weed species composition, occurrence and harm characteristic,providing foundation for using herbicide depending on weeds species. Providing theoretical foundationfor further study in chemical control in the north of Heilongjiang Province. In this study we have foundthe formula of chemical weeding in the region, helping to solve the more weeds than crops problem insoybean fields. For soybean field weed control in the north of Heilongjiang province provides atechnical support, for farmers to increase soybean production, increase benefits and play their role topromote the region agricultural economic development.