## 2 Materials and Methods
### Field Trials
#### 2.2.4 Experimental Design  
Spray Deposition and Coverage Evaluation  
The spray trials quantified spray deposition and coverage following a randomized split-split plot design. Mylar cards (size: 5.1 \(\times\) 5.1 cm, Stark Boards, CA, USA) and water sensitive papers (WSP) (size: 2.5 \(\times\) 2.5 cm, Syngenta Crop Protection Inc., Greensboro, NC, USA) were used to quantify spray deposition and coverage, respectively (Figure 4). The spray deposition was enumerated by evaluating the amount of active ingredient deposited on the unit area of the mylar card (ng cm\({}^{-2}\)). The spray coverage was defined as the percentage area of the WSPs stained by the spray mix. Three trees were randomly selected from the treatment blocks (Figure 3), and the sampling trees were divided into east and west canopy sides. The canopy was further divided in three zones (bottom: 0.6 to <1.4 m, mid: 1.4 to <2.2 m and top: 2.2 to 3.0 m) that resulted in six sampling zones per tree (top-east, top-west, mid-east, mid-west, bottom-east, and bottom-west) (Figure 4e). In each of the sampling zones, two leaves were randomly selected to install mylar card and WSP samplers. The samplers were installed in each of the canopy zones by clamping them onto the adaxial and abaxial leaf surfaces using customized alligator clips. The active surface of WSPs were oriented upward and downward at adaxial and abaxial leaf surfaces, respectively (Figure 4d). A total of 108 mylar cards and WSP samplers (3 blocks \(\times\) 3  
Figure 3: The schematics of experimental plot (not drawn to the scale). The dotted red boxes indicate the blocks treated with irrigation micro-emitter (T1), the solid blue boxes indicate the blocks with hollow cone nozzle treatment (T2), and the circular dots represents the sampled trees within a block.  
trees/block \(\times\) 2 sides/tree \(\times\) 3 zones/side \(\times\) 2 leaf surface/zone \(\times\) 1 sampler/leaf surface) were collected for each treatment under study.  
Off-target spray losses were assessed in line with the randomized plots of canopy evaluations. Run-off and drift deposited on the ground and losses in the air were evaluated based on the schematic depicted in Figure 5. Sub-tree run-off includes the spray deposited underneath the trees because of the spray droplets settled to the tree bottom under gravity, rebounded droplets from the canopy and run-off due to canopy saturation. The run-off was evaluated with mylar card samplers (size: 5.1 \(\times\) 5.1 cm) installed on a wooded block (size: 10 \(\times\) 10 cm) placed below the replicate trees. Similarly, the downwind mid-row ground drift losses were evaluated using mylar card samplers located at a distance of 1.5, 4.5 and 7.5 m from the block being sprayed (Figure 5). The aerial drift losses were assessed by evaluating the tracer deposition above the tree canopy downwind to the block being sprayed. A customized PVC mast was utilized to hold mylar card samplers at a height of 3.3, 3.6 and 3.9 m above ground level. Two masts, carrying three samplers, were positioned 3 and 6 m downwind to evaluate the aerial drift losses (Figure 5). In addition to mylar card samplers, WSP samplers (size: 2.5 \(\times\) 2.5 cm) were also installed at each of the drift quantification location to cross verify any contamination of mylar card samplers while handling and analysis [21].  
Figure 4: The field installation of (**a**) modified irrigation micro-emitter and (**b**) off-the-shelf nozzle utilized for respective SSCDS treatments, and the deposition and coverage analysis of the tested treatments with help of the (**c**) mylar card and the (**d**) water sensitive paper samplers installed in (**e**) three canopy zones on east and west side (top-east, top-west, mid-east, mid-west, bottom-east, and bottom-west).