Survey Of Weeds In Paddy Fileds In Chongqing And Study On35%Cyhalofop-butyl-Cinosulfuron Water Dispersible Granule

Rice as food crop is of the largest planting area and most yield in China. More than half of the farmers across the country have engaged in production of rice cultivation, and more than65%of the population consume rice for the staple food. Paddy field weeds have important bad influence on the rice yield and quality, so we must control them, and chemical control is the most important and main means to control paddy field weeds in our country. Soil-applied herbicides used in paddy fields are given priority to in China, generally applied in weed sprouts (seedling) stage, but herbicides by foliar application are relatively few.Based on the result of survey of weeds in paddy fields in Chongqing, combined of the development trend of herbicide, the purpose of this paper is to develop a kind of high efficient and safe herbicide mixing agent with advanced dosage-form by foliar application which is adapted to control single and double-cotyledon weeds in paddy fields in Chongqing and study its application technology.After decided on two kinds of active ingredients, we had taken Echinochloa crus-galli (L.) P. Beauv. belonged to gramineous weeds and Eclipta prostrata (L.) L. belonged to broadleaf weeds as test materials, determined optimal ratio of Cyhalofop-butyl and Cinosulfuron compounds through laboratory biosaaays. And then through the auxiliary selection and formula optimization, we had obtained qualified laboratory product of35%Cyhalofop-butyl·Cinosulfuron water dispersible granule and set up its quality control indexes. At last, we had detemined the quantity of the preparation applied in paddy fields in Chongqing through the field efficacy trials, which laid a foundation for the product registration promotion and practical application. In this paper, the main results are as follows: 1. Survey of weeds in paddy fields in ChongqingUsing the method of sampling survey, we conduct a survey of weeds in paddy fields in Chongqing in2010July. The result of survey has shown that there are33kinds of weeds in paddy fields in Chongqing, which belong to20families.12main weeds, which relative abundances are equal to or greater than10, include Lemna minor L, Echinochloa crus-galli (L.) P. Beauv, Sagittaria trifolia L, Alternanthera philoxeroides (Mart.) Griseb, Najas minor All, Monochoria vaginalis (Burm. f.) Presl ex Kunth, Rotala rotundifolia (Buch.-Ham.) Koehne, Ludwigia prostrata Roxb, Eclipta prostrate (L.) L, Monochoria korsakowii Regel&Maack, Marsilea quadrifolia L, Azolla imbricata Lam. The foremost5kinds of weeds, which relative abundances are greater than20, can be regarded as the dominant weeds in paddy fields in Chongqing.Meanwhile, we have found that there are19kinds of weeds in paddy fields with chemical weed control in Chongqing, which belong to14families. There are11main weedswhich relative abundances are equal to or greater than10. they include Alternanthera philoxeroides (Mart.) Griseb, Echinochloa crus-galli (L.) P. Beauv, Rotala rotundifolia (Buch.-Ham.) Koehne, Lemna minor L, Eclipta prostrata (L.) L, Sagittaria trifolia L, Leptochloa chinensis (L.) Nees, Ludwigia prostrata Roxb, Paspalum distichum L, Polygonum lapathifolium L, Azolla imbricata Lam. The foremost5kinds of weeds, which relative abundances are greater than20, can be regarded as weeds which are difficult to be controlled in paddy fields in Chongqing.2. Determination of biological activity of herbicidesAccording to the usage of paddy herbicides in our country and occurrence of weeds in paddy fields in Chongqing region, combination of weed control spectrum and application characteristics of Cyhalofop-butyl and Cinosulfuron, we made use of Cyhalofop-butyl and Cinosulfuron to develop a kind of new paddy herbicide mixing agent. Indoor bioassay results showed that:the mixed effects on Echinochloa crus-galli (L.) P. Beauv and Eclipta prostrata (L.) L of Cyhalofop-butyl and Cinosulfuron were additive effects. Their mixed proportions of Cyhalofop-butyl:Cinosulfuron were (0.83～5.3):1(m/m), the optimal proportion of Cyhalofop-butyl:Cinosulfuron was5:1or3:2. This research used the proportion of3:2.3. Determination of35%Cyhalofop-butyl-Cinosulfuron WG formulaThrough indoor additives selection and formula optimization, we determined35% Cyhalofop-butyl·Cinosulfuron WG formula as follows: Elements quality percentage Cyhalofop-butyl21%Cinosulfuron14%Wetting agent:Sodium dodecyl benzene sulfonate4%Dispersant:Sodium lignosulphonate6-10%(optimal amount:10%) Disintegrating agent:Sodium chloride4-6%(optimal amount:5%) Carrier:kaolin up to100%4. Quality inspection of35%Cyhalofop-butyl-Cinosulfuron WG sampleUsing the methods commended by FAO and GB, we had on quality inspection of35%Cyhalofop-butyl·Cinosulfuron WG sample. The results were as follows: appearance (yellow cylindrical particle), particle size (1～2mm); wetting time (7.3s), disintegrating time (47s); suspension rate (89.17%); qualified dispersion and fineness; water content (0.81%); pH value (6.1～6.7); thermal decomposition rate of Cyhalofop-butyl (0.85%) and thermal decomposition rate of cinosulfuron (1.27%). The above results indicated that quality indexes of35%Cyhalofop-butyl·Cinosulfuron WG conformed to quality testing standards of water dispersible granule.5. The field efficacy trials of weed control by35%Cyhalofop-butyl·Cinosulfuron WG in paddy fieldsThe results of filed efficacy trials showed35%Cyhalofop-butyl·Cinosulfuron WG had good control effect on weeds in paddy fields, especially had excellent control effect on Rotala indica (Willd.) Koehne and Monochoria vaginalis (Burm. f.) Presl ex Kunth. When the field dosage was60～75g·ai/hm2, the control effect of35%Cyhalofop-butyl·Cinosulfuron WG was maintained at86.1%-91.2%sprayed after15～35d, which was significant, at the same time, it was safety to rice. In the principles of high efficiency, economy and environmental protection, we recommended the field dosage of35% Cyhalofop-butyl-Cinosulfuron WG was60～75g·ai/hm2.