Preliminary Study On Enhancement Effect And Mechanism Of Organosilicon Adjuvants On Nicosulfuron

The absorption of the active ingredient of the herbicide by the weeds and its effective arrival to the action site are the key factors affecting the control efficacy. Choosing certain adjuvant to improve the wetting and extending of herbicide formulation on the weed leaf will help the weed absorb the active ingredient, improve its control effectiveness, reduce its dosage against environmental pollution and promote economic benefit. With the development of new type of foliar-applied herbicides and the rise of modern precision agriculture, the development and application of the herbicide adjuvant are gained more attention.Nicosulfuron, as important foliar-applied herbicide in corn field and for its broad spectrum, high biological activity, easy mixture, high safety to the following crops, flexible use and good environmental compatibility, has a great development value and good application prospect in China. However, for its poor extending and low uptake on the weed leaves, application rates nicosulfuron WP is higher in practice. So the addition of certain adjuvants into spraying formulation is an effective pathway to improve the control effectiveness and reduce dosage.Six kinds of organosilicone adjuvants, Breakthru S200, Breakthru S233, Breakthru S240, Agrowet810c, Agrowet818, and Silwet408, were chosen to determine their enhancement action to promote the control efficacy. The results showed that Agrowet810c had the best enhancement effect among six adjuvants. The application techniques and enhancement mechanism of Agrowet810c were studied to lay the solid theoretical basis on the application of the herbicide in corn field. All he results were as follows.1. The enhancement action of six organosilicone adjuvants on nicosulfuron for controlling barnyardgrass (Echinochloa crusgalli) and piemarker (Abutilon hybridum) was measured by pot test in greenhouse. The results showed that enhancement action was changeable among all the adjuvants, especially the enhancement action for controlling barnyardgrass with fresh weight reduction from 40.22% to 45.4% was much higher than for controlling piemarker with the highest 20.21%. Comparatively, the enhancement action of Agrowet810c and Agrowet818 were better, following by Breakthru S233 and Silwet 408, and Breakthru S240 and Breakthru S200 worst.2.The enhancement effect of different organosilicon contents on the control efficacy was explored by pot test in greenhouse. The results indicated that the enhancement effect increased with the increasing concentration of organosilicon ranging from 0.01% to 0.05% (w/w). However, when the concentration was over 0.03% (rigweed, Amaranthus retroflexus) and 0.04% (barnyardgrass), the enhancement effect was not significantly different.3.The influence of six organosilicon adjuvants mixed into nicosulfuron on crop safety was studied in greenhouse and in the field. The greenhouse trial showed that the corn height and fresh weight inhibition rates of nicosulfuron with adjuvants were slightly higher than or close to that without adjuvants, and the phytotoxicity level was zero. The field trials indicated that nicosulfuron (80%WP) mixed with 0.04 % Agrowet810c was safe to corn at the range of the test doses.4.The enhancement mechanisms of Agrowet810c was primarily researched by measuring the surface tension, contact angle, drying time and deposition amount on plant leaf. The results showed:(1)organosilicon adjuvant could markedly decrease surface tension of the tested herbicide solution. the surface tension of nicosulfuron solution without adjuvants can be reduced by 40.82% of free water surface tension, while pulsing Agrowet810c into solution, the surface tension reduction was over 70%; ( 2 )Organosilicon adjuvant could distinctly decrease contact angle of the tested herbicide solution. While pulsing 0.01～0.05% of Agrowet 810c to solution, the contact angle of the herbicide distinctly decreased, and all decrease range were over 85%, the highest 100%;(3)Organosilicon adjuvant could obviously shorten drying time of the tested herbicide solution. When pulsing 0.01～0.05% of Agrowet810c to solution, the drying time of all the nicosulfuron solution was shortened over 56.66%, compared with solution without adjuvant; (4)Agrowet 810c could increase deposition of Ponceau G solution on cabbage leaf, but the deposition on rice leaf was relatively lower.