اثر متقابل نوع مویان اُرگانوسیلیکونی و حجم پاشش بر کارایی دیکلوفوپ-متیل در کنترل یولاف وحشی زمستانه

در تحقیق گلخانه ای حاضر، اثر نوع مویان تری سیلوکسانی و حجم پاشش بر فعالیت علف کش دیکلوفوپ-متیل علیه یولاف وحشی زمستانه ارزیابی شد. تحقیق به صورت فاکتوریل در قالب طرح کاملاً تصادفی انجام گرفت که فاکتورها شامل مقدار علف کش (صفر، 112.5، 225، 450، 900 و 1350 گرم در هکتار)، حجم پاشش (60، 120، 240 و 480 لیتر در هکتار)، نوع مویان (بِریک-ترو اِس 233 و بِریک-ترو اِس 240) و غلظت مویان (صفر، 0.0125، 0.025، 0.05، 0.1، 0.2، 0.4 و 0.8 درصد حجمی) بودند. ماده خشک یولاف وحشی زمستانه روی مقادیر دیکلوفوپ-متیل برازش داده شد تا مقدار علف کش لازم جهت کنترل 50 و 90 درصدی (ed50 و ed90) بدست آید. در شرایط بدون مویان، با افزایش حجم پاشش از 60 به 480 لیتر در هکتار مقادیر ed50 به ترتیب از 536.4 به 865.1 گرم در هکتار و مقادیر ed90 به ترتیب از 815.3 به 1366.8 گرم در هکتار افزایش یافت. رابطه ای منفی بین کارایی دیکلوفوپ-متیل و حجم پاشش مشاهده شد. این مشاهده با کاربرد هر دو مویان در غلظتهای 0.0125 تا 0.1 درصد حجمی نیز مشاهده شد. در غلظتهای بالاتر، حالت رابطه از منفی به خنثی برای بِریک-ترو اِس 233 تغییر کرد؛ ولی برای بِریک-ترو اِس 240 این حالت تغییری نکرد. ضرورت قطرات پاشش کوچک تر و غلیظ تر برای عملکرد بهتر دیکلوفوپ-متیل محرز گردید. در حجم پاشش کم (60 لیتر در هکتار)، بِریک-ترو اِس 233 در غلظت کم (بین 0.1 تا 0.2 درصد حجمی) ولی بِریک-ترو اِس 240 در غلظت بالا (بین 0.2 تا 0.8 درصد حجمی) کارآمدتر بودند.

the interaction of organosilicon surfactant type and spray volume on diclofop-methyl efficacy in control of winter wild oat

introductiondiclofop-methyl is labeled for use in wheat and barley to control many grassy species, e.g., the genus avena. efforts should be made to use diclofop-methyl correctly, allowing the reduced doses to be applied. the response of herbicides to spray volume is different. after determining a suitable spray volume for a foliage-applied herbicide, the next step is to adjust it. the spray volume can be adjusted by two methods: the change in application speed or nozzle size. if less spray volume is necessary to apply an herbicide, it is needed to increase application speed. it causes the spray droplets to be more bounced or shattered from the leaf surface, causing the herbicide not to achieve optimal efficacy. therefore, selecting a smaller orifice nozzle is much more applicable, of course, if the spray drift is controlled. the surface tension of water, which is used to spray herbicides, can be slightly reduced after adding the formulation of herbicides. therefore, the relatively high surface tension of the spray solution poses three main problems. first, the spray droplets can easily be bounced off the leaf surface. second, those remaining on the leaf surface after impact have a relatively spherical shape. third, the crystalline wax in the cuticles, is considered an essential barrier to penetrating herbicides into the leaf tissues. it is well-established that the three main issues mentioned above can be addressed by selecting a suitable surfactant to add to the spray solution. this addition enables optimal efficacy of the herbicide. consequently, numerous previous studies have highlighted the superiority of trisiloxane surfactants over non-silicone surfactants in enhancing herbicidal activity. this study aims to assess whether the effect of spray volume, adjusted by changing nozzle size, on the herbicidal activity of diclofop-methyl could be influenced by two types of trisiloxane surfactants – one with super wetting properties and the other with non-super wetting properties. materials and methodsa greenhouse trial was performed as a dose-response relationship at the bu-ali sina university, hamedan, iran. the experiment was designed as a four-factor completely randomized design. the first factor was the dose of diclofop-methyl (illoxan® ec 36%) including 0, 112.5, 225, 450, 900 (labeled dose), and 1350 g ha-1. the second factor was spray volume, including 60, 120, 240, and 480 l ha-1, which were adjusted using 1100075, 110015, 11003, and 11006 flat fan nozzle, respectively. the third factor was two types of trisiloxane surfactants, break-thru® s 233 having a non-super wetting property and break-thru® s 240 having a super wetting property. both are non-ionic surfactants and manufactured by evonik company in germany. they formed their critical micelle concentration (cmc) at 0.1% v v-1 at which the surface tension of distilled water (72.1 mn m-1) containing break-thru® s 233 and break-thru® s 240 was measured to be 24.1 and 22.6 mn m-1, respectively. the fourth factor was surfactant concentration, including 0, 0.0125, 0.025, 0.05, 0.1, 0.2, 0.4, and 0.8% v v-1 (a range from ⅛ to 8 cmc, respectively). a compressor sprayer was used to apply the treatments at 300 kpa spray pressure. a nonlinear regression analysis was conducted to analyze the ‘drc’ using the software r. results and discussiona 40% increase in the ed50 value occurred with increasing the spray volumes from 60 to 480 l ha-1 (536.4 and 865.1 g ha-1, respectively), indicating a negative relationship between diclofop-methyl activity and spray volume.