Selection of suitable nozzle type, regarding the size of droplets and the volume of spray to apply herbicides optimally is necessary. In the spray deposition experiment, conducted using a factorial (six nozzle types × two nozzle sizes) arranged as a completely randomized block design, the moisture-sensitive papers were used and localized in four positions. In dose-response experiment, six doses of clodinafop-propargyl(0, 8, 16, 32, 48, and 64 gr.a.i. ha-1) were sprayed using six nozzle types with two nozzle sizes (11002 and 11004) at five-leaf growth stage of winter wild oat. As the nozzle number increased, more surface area of all moisture sensitive papers was wetted. Although the size of droplets increases with increasing the size of nozzles, the efficacy of clodinafop-propargylto controlwinter wild oat was increased. For the nozzles size of 11004, the performance of nozzles in the efficacy of clodinafop-propargylbased on the ED90 values was as Twin Fan Standard > Standard Flat Fan > Compact Fan Air > Twin Fan Low Drift > Fan Low Drift > Twin Fan Air.

When a contact herbicide is applied in the dark time of a day than in the light time, better weed control will be observed. Velvetleaf is a typical example of weeds in displaying the phenomenon of foliar Nyctinasty. This feature causes the leaf surface of velvetleaf is perpendicularly oriented to the ground during the dark time of day. As a result, when a contact herbicide is applied in the dark time of the day by a single flat fan nozzle which generates a perpendicular motion of spray droplets to the ground, the leaf surface of velvetleaf cannot be covered well. Therefore, the foliar Nyctinasty in velvetleaf reduces the efficacy of contact herbicide applied in the dark time of day. The main hypothesis leading this study was that if the motion of spray droplets is not perpendicular to the ground, it is possible to wet the leaves of velvetleaf in the dark time of day. In this study, the effects of using twin flat fan nozzles which generates a non-perpendicular motion of spray droplets to the ground in comparison with single flat fan nozzle on the efficacy of Paraquat at the different times of day were investigated.

This study was conducted in outdoor conditions at Bu-Ali Sina University, Hamedan, Iran. Treatments consisted of five doses of Paraquat (0, 75, 150, 300, and 600 g a.i. ha-1) using three types of nozzles (single anti-drift flat fan, twin anti-drift flat fan 2020, and twin anti-drift flat fan 7030) in two nozzle sizes (110015 and 11002) at four times of day (before sunset at 20:00, after sunset at 22:00, before sunrise at 05:00, and after sunrise at 7:00) with four replications which were sprayed at the six-to-seven-leaf stage of velvetleaf. Two days after spraying at 7:00, the shoots of velvetleaf were harvested nearly 1 cm above the soil surface. The individual fresh: dry weight ratio was used to analyze as nonlinear regression using a four-parametric logistic model.

 At all four application times of the day, increasing the nozzle size of single anti-drift flat fan nozzle increased the dose of Paraquat required for the 90% desiccation of velvetleaf shoots. While, except at some application times of day (22:00 and 07:00 in the case of twin anti-drift flat fan nozzle 2020 and 5:00 in the case of twin anti-drift flat fan nozzle 7030), increasing the nozzle size of twin anti-drift flat fan nozzles decreased the dose of Paraquat required for the 90% desiccation of velvetleaf shoots. Except in some cases (11002 twin anti-drift flat fan nozzle 2020 and 110015 twin anti-drift flat fan nozzle 7030), when Paraquat was sprayed with any nozzle size at 20:00 and 07:00, there was no significant difference in its efficacy. When Paraquat was sprayed with any nozzle size at 20:00 and 07:00, there was no significant difference in its efficacy. But, when it was sprayed with any nozzle size at 22:00 and 05:00, a significant difference in its efficacy was observed. So, the dose of Paraquat required for the 90% desiccation of velvetleaf shoots at 22:00 was significantly lower than that at 05:00. Our principal hypothesis in this study was confirmed. As when Paraquat was applied with twin anti-drift flat fan nozzles in the dark time of day, it more effectively improved the desiccation of velvetleaf shoots.

The treatment of the application of Paraquat with 11002 twin anti-drift flat fan nozzle 7030 at 22:00 required the minimum Paraquat dose to create the same desiccation intensity as other treatments. Therefore, this treatment is recommendable.

Herbicides should be sprayed on weeds after diluting in water. Since the spray volume can affect the efficacy of herbicides; therefore, selecting an appropriate spray volume has always been considered a simple, inexpensive and available method to optimize the efficacy of herbicides. Changing the sprayer speed and the nozzle size are two possible methods to adjust the spray volume. If a very low or high spray volume is required to achieve optimal herbicide efficacy, the applicability of the first method will be problematic. For this reason, the method of changing the nozzle size always seems to be more feasible.. When a graminicide is sprayed with a single flat fan nozzle, which is currently the most common type of nozzle available to most Iranian farmers, the spray droplets which move perpendicular to the ground are mostly oblique to the leaf surface of the grass, having erect leaves. Hence, it is likely that a large number of the spray droplets bounced from the leaf surface to the soil. A twin flat fan nozzle can create two non-vertical sprays, reducing the possibility of impacting obliquely the spray droplets to the leaf surface. Therefore, the bouncing of spray droplets from the leaf surface is significantly reduced. To date, the efficacy of twin symmetrical and asymmetrical flat fan nozzles has not been compared. On the other hand, the effect of spray volume on haloxyfop-r-methyl efficacy against wild barley has not been evaluated. Therefore, this experiment was intended to fill the gaps mentioned in science.

To compare the efficiency of single, twin symmetrical and twin asymmetrical flat fan nozzles under different spray volumes, a dose-response experiment was performed in the Research Greenhouse of Bu-Ali Sina University. In this experiment, seven doses of haloxyfop-r-methyl (0, 10.8, 21.6, 43.2, 64.8, 84.4 and 108 g a.i. ha-1) were used using three types of nozzles (single flat fan, twin flat fan 2020 and twin flat fan 3070) in six sizes of them (110015, 11002, 110025, 11003, 11004 and 11005, which create the spray volumes of 150, 200, 250, 300, 400 and 500 L ha-1, respectively) were sprayed on wild barley at a three-leaf stage. Simultaneously with spraying 108 g a.i. ha-1, another experiment was performed as a factorial in a completely randomized design. In this experiment, the amount of spray settling from three types of nozzles in six sizes of on moisture-sensitive papers was evaluated in three situations. Paper No. 1 was mounted horizontally on the ground and papers No. 2 and 3 were mounted vertically facing the back and back of the nozzle, respectively. 

In paper No. 1, in all types of nozzles, more surface of the paper was wetted by increasing the nozzle size (spray volume). In all types of nozzles at 11003, 11004 and 11005, the highest wetting rate was provided (100%). The lowest wetting rate was obtained with twin flat fan 3070 at 110015 (7.3%). In paper No. 2, in all types of nozzles, more surface of the paper was wetted by increasing the nozzle size. The highest wetting rate (100%) was observed with single flat fan and twin flat fan 2020 nozzles at 11003, 11004 and 11005. The lowest wetting rate (24-19%) was observed with single flat fan nozzle at 110015 and 11002. In paper No. 3, in two twin flat fan nozzles, more surface of the paper was wetted by increasing the nozzle size. A single flat-fan nozzle could not wet the paper at all. In general, the performance of the nozzles used in this experiment is twin flat fan 2020 > single flat fan = twin flat fan 3070. In all types of nozzles, with increasing the size of nozzles (spray volume), the rate of haloxyfop-r-methyl is required to reduce 50 and 90% of the dry weight of wild barley (ED50 and ED90) increased significantly, indicating a decrease in the efficacy of haloxyfop-r-methyl against wild barley. As the best treatment, the lowest values of ED50 and ED90, which were equal to 9.34 and 38.21 g a.i. ha-1, respectively, were obtained with twin flat fan 2020 at 110015. Increased efficacy of haloxyfop-r-methyl when spray volume was reduced can be explained as follows small size nozzles create a greater small droplet. Smaller droplets may give better spray retention over the leaf surface, resulting in increased efficacy of haloxyfop-r-methyl. In low spray volume, the higher concentration of herbicide in the spray solution may create a greater concentration gradient between the spray solution and leaf, increasing the diffusion of herbicide into the leaf.

Although the spray coverage increased with increasing spray volume for haloxyfop-r-methyl, it has an adverse effect on its efficacy. Therefore, smaller and more concentration droplets resulted in greater control of wild barley with haloxyfop-r-methyl than did larger and more dilution droplets.

The herbicide application has caused some environmental problems. Therefore, optimal application of herbicides was followed in recent years. For this purpose, it is essential to minimize the exo-drift and/or endo-drift of spray droplets. The amount of exo-drift and/or endo-drift is directly related to the size of spray droplets. By decreasing the size of spray droplets, the exo-drift increases and the endo-drift decreases (34). This intricate issue is a stimulus to develop the types of nozzles in different sizes (color) producing different sizes of spray droplets at different spraying pressures. Such a development in the production of nozzles has caused difficulty and confusion in selecting a suitable type of nozzle (2). On the other hand, the agriculture sector is faced with water crisis in recent years. Considering that water is the most important carrier of herbicides, selecting a suitable spray volume is thus necessary. According to previous studies (26), the efficacy of different herbicides can influence spray volume negatively (30), neutrally (29), or positively (12). So far, the effect of spray volume on the efficacy of cycloxydim against any weed has not been investigated. Also, since the types of triplet flat fan nozzles have been recently developed, no investigation has been done on their performance compared to the types of single and twin flat fan nozzles. The current study aimed to fill this knowledge gap.   

The seeds of wild barely (Hordeum spontaneum Koch.) were treated to germinate. Then, 8 seedlings were planted within each 3-L pot and grown in the Research Greenhouse of Bu-Ali Sina University, Hamedan, Iran. At the four-leaf stage, they were treated with 0, 6.25, 12.5, 25, 50, and 100 g cycloxydim ha-1 using 3 nozzle types (i.e. Standard, Anti-Drift, and Air Induction), at 3 orifice numbers (i.e. single, twin, and Triplet) and 3 nozzle sizes (i.e. 11002, 11003, and 11004). The treatments were sprayed at a pressure of 300 kPa when the wind speed was less than 0.4 m s-1. The volume of spray created by 11002, 11003, and 11004 nozzle sizes was 160, 240 and 320 L ha-1, respectively. Three weeks after spraying, the dry weight of plants was determined. The date were fitted using a four-parameter log-logistic model to estimate the dose required to achieve 50% wild barley control (ED50).
 

The ED50 was significantly affected by the type, size, and orifice number of nozzle. In all types of nozzles (Standard, anti-Drift and Air Induction) and sizes (11002, 11003 and 11004), an increase in orifice number significantly reduced the values of ED50 for cycloxydim against wild barely, indicating increased efficiency of herbicide. This can be explained by two reasons. Firstly, with an increase in orifice number in each type of nozzles, the size of spray droplets decreases. Previous studies have proven that there is a negative relationship between the amount of spray droplets deposited on the target surface and the size of spray droplets. Therefore, by decreasing the size of spray droplets, they can be deposited more on the target surface, resulting in an improvement in the foliage-herbicides efficiency. Secondly, increasing the orifice number of nozzle can lead to the penetration of spray droplets into the canopy. Among the nozzles of 11002 in any orifice number, the performance of nozzles was ranked as Standard > Anti-Drift > Air Induction. However, among the nozzles of 11003 or 11004 in any orifice number, the performance of nozzles was as Standard = Anti-Drift > Air Induction. Among all types of nozzles in any orifice number, increasing spray volume from 160 to 240 L ha-1 reduced the ED50. However, only in the types of nozzles of Air Induction in any orifice number, increasing spray volume from 240 to 320 L ha-1 reduced the ED50. 

It can be recommended that the most suitable nozzle for the application of cycloxydim against wild barely at a wind speed of less than 0.4 m s-1 with the aim of optimizing simultaneously both the dose of herbicide and the consumption of water is "Triplet Standard Flat Fan Nozzle 11003 " (spray volume= 240 L ha1).

Whether fenoxaprop-p-ethyl activity could be affected by the carrier volume and whether this relationship can be affected by two types of bio-surfactants, rhamnolipid and surfactin, was assessed under greenhouse conditions. Treatments consisted of herbicide dose (0, 18.75, 37.5, 56.25, 75, and 93.75 g ha-1), spray volume (60, 120, 240, and 480 L ha-1), surfactant type above, and surfactant concentration (0, 0.125, 0.25, 0.5, 1, 2, 4, and 8x critical micelle concentration (CMC). The dry matter of sterile oat was regressed over the doses of fenoxaprop-p-ethyl to obtain a dose causing 50% sterile oat control (ED50). Without surfactant, a 38% increase in the ED50 with increasing the spray volumes from 60 to 480 L ha-1 (44.7 and 72.1 g ha-1, respectively) revealed a negative relationship between fenoxaprop-p-ethyl activity and spray volume. In other words, a low-volume spray solution, creating smaller, more concentrated spray droplets, is necessary to get the optimal action of fenoxaprop-p-ethyl. This relationship could also be observed when both surfactants were used at 0.125 to 1x CMC. At 2 to 8x CMC, the relationship mode changed from negative to neutral for rhamnolipid, while it did not change for surfactin. This study shows that, unlike surfactin, rhamnolipid worked better at a low concentration in a low-volume spray solution to get the optimal action of fenoxaprop-p-ethyl.

Diclofop-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.

A 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.

A 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. Adding Break-Thru® S 233 at 0.025% v v-1 to 60, 120, 240, and 480 L ha-1 spray volumes caused a 1.16, 3.31, 2.04, and 2.13-fold decrease in the ED50 value compared with no surfactant at their corresponding spray volumes, respectively. While, adding Break-Thru® S 240 at 0.025% v v-1 to 60, 120, 240, and 480 L ha-1 spray volumes caused a 1.39, 1.32, 1.34, and 1.19-fold decrease in the ED50 value compared with no surfactant at their corresponding spray volumes, respectively. A decrease in the ED50, attributed to the addition of surfactants, signifies an enhanced activity of diclofop-methyl against sterile oat. This improvement may stem from a reduction in the surface tension of the spray solution, resulting in an expanded retention and/or spreading area of the spray droplets on the leaf surface. This, in turn, facilitates increased penetration of the herbicide into the leaf tissue. These findings indicate that Break-Thru® S 233 works better when added at low concentration to a low-volume spray solution, while Break-Thru® S 240 works better when added at high concentration to a low-volume spray solution. It can be attributed to the difference in the wetting property of surfactants. The natural relationship between diclofop-methyl activity and spray volume at higher concentrations of Break-Thru® S 233 may be related to its phytotoxic effect, resulting in an antagonism effect on diclofop-methyl activity against sterile oat. In the case of Break-Thru® S 240, the relationship mode between diclofop-methyl activity and spray volume was not affected by surfactant concentration indicating the lack of phytotoxic effect by this surfactant.

The current study revealed a negative relationship between diclofop-methyl efficacy and spray volume, which was adjusted by nozzle size. Although this finding differs from a previous study in which spray volume has been adjusted by application speed, they showed that the effect of spray volume on the herbicide’s efficacy depends not only on herbicide but also on how it is adjusted. The smaller, more concentrated spray droplets are necessary to get a better action of diclofop-methyl against sterile oat. However, the negative relationship observed between diclofop-methyl efficacy and spray volume could also be observed with two types of trisiloxane when they surfactants, were used at 0.0125 to 0.1 v v-1. While, when they were used at 0.2 to 0.8% v v-1, the relationship mode changed from negative to neutral for Break-Thru® S 233, but it did not change for Break-Thru® S 240. Moreover, Break-Thru® S 240 works better when added at high concentration to a low-volume spray solution due to the danger of spray run-off, while Break-Thru® S 233 works better when added at low concentration to a low-volume spray solution due to its phytotoxic effect.

Controlling the humidity and temperature inside the greenhouse is an effective way of plant growth that could be done in different ways. The humidity and temperature of the greenhouse environment could be controlled by the fogging system. A uniform humidity in the greenhouse could be achieved by investigating the effect of various factors on the fluid flow behavior when leaves the spray nozzle. In this study, the effect of three types of BD power fuel injector nozzles (made in Taiwan) in various numbers of 0.03, 0.04, and 0.05 in three pressure levels of 20, 40, and 60 bar on the pattern of fog spray in the environment, spray angle, and spray uniformity was examined. Both methods of experimental and computational fluid dynamics modeling used in this study. For experimental examinations, the greenhouse of Yasuj Airport was used. For evaluation of experimental examinations, a factorial experiment in randomized complete block design with 3 replications was used and to compare the means of treatments Duncan's test was used. To solve the governing equations of flow such as continuity and momentum in the modeling method, FLUENT software is used. The results from experimental study showed that there is a significant association between pressure and nozzle type on the spray angle (P<0.01). The highest fluid spraying was observed in the outlet center of the nozzle, and by moving away from the center of the nozzle the amount of fluid settling was reduced. In this type of sprayer, the best spraying quality was obtained at a pressure of 40 bar. The results from simulation of particle velocity showed that at the pressure of 20 bar, the trend of velocity changes is V-shaped. In the center of the nozzles the velocity of the particles was maximum and then decreased as the particles move towards the sides. Any increments in pressure led to spraying non-uniformity and phenomenon of elongation. However, both simulation and experimental results were matched appropriately.