*3.2. Canopy Temperature Calculation*

The differences in estimated canopy temperature between the four canopy extraction methods were evident at both the whole orchard and MC scales (Figure 5). The most striking difference between the methods in the whole orchard histograms of canopy temperature was the range of values. The temperature ranges of the extracted canopy pixels using the RGB-BM method was substantially wider (30–64 ◦C) than that of the 2PE (30–42 ◦C), ED (30–46 ◦C), and VS (30–47 ◦C) methods. The "tail" of the warm pixels of the RGB-BM histogram is the result of non-tree canopy being misclassified as canopy. These warm pixels were located between tree rows that contained grasses and soil but were free of tree canopy material, and they are illustrated in the RGB-BM temperature map of the MC 5 (Figure 5 left image column). The ExG index, which is the basis for the RGB-BM method, seemingly had difficulty differentiating between the different types of plant material. However, this method was noticeably able to detect slight differences between canopy and non-canopy pixels within the tree canopy, in contrast to the 2PE, ED, and VS methods which pixels were all relatively coarse.

**Figure 5.** Canopy temperature histogram of the whole orchard for the 2-pixel erosion (2PE), edge detection (ED), vegetation segmentation (VS), and RGB binary masking (RGB-BM) canopy extraction methods on 12 August 2019. Images of all extracted canopy temperature pixels (T100%) of the management cell (MC) 5 (left image column) and the highlighted (turquoise) coolest 33% of canopy temperature pixels (T33%) (right image column) for all canopy extraction methods.

The VS method histogram is characterized by a larger number of pixels between 38 and 47 ◦C compared to the other methods (Figure 5), indicating that not all mixed pixels have been properly removed. The edges of canopy material (between one and three pixels) are noticeably warmer than other parts of the canopy throughout the orchard. Additionally, many between-row pixels of the MC 4 (not shown) were misidentified as canopy pixels. The MC 4 was defined as stressed and irrigated according to the SWPe value. Over-irrigation supposedly caused waterlogging in specific locations and relatively wet soil in others, and it directly affected the pixel temperature in this MC (Figure 3 outlier).

Visible differences were evident between the spatial patterns of the extracted canopy pixels and the coolest 33% of the canopy pixels for each canopy extraction method (Figure 5); however, relatively small differences were noted in the spatial patterns between the coolest 33% canopy pixels of all extraction methods (Figure 5 right image column). Notable differences were found between the canopy temperatures calculated using the average 100% of canopy pixels (T100%) and the average of the coolest 33% of canopy pixels (T33%) (Figure 6). The average T100% values were higher than those of T33% for each canopy

extraction method: 1.28 ◦C (ED), 1.37 ◦C (2PE), 2.85 ◦C (RGB-BM), and 3.02 ◦C (VS). Additionally, the T100% calculation emphasized the differences between the extraction methods. The RGB-BM and VS methods yielded considerably higher T100% than the 2PE and ED methods. The value of the VS method was, on average, 1.91 ◦C higher than the 2PE method, while the average differences between the 2PE and ED methods were minimal (0.13 ◦C). The T33% dataset was characterized by minimal to slight differences between the canopy extraction methods: an average difference of 0.04 ◦C between the 2PE and ED methods and of 0.26 ◦C between the VS and 2PE methods.

**Figure 6.** Canopy temperature (◦C) calculated by the average 100% (T100%) and by the average of the coolest 33% (T33%) of canopy pixels per management cell (MC) between 21 July and 26 Aug 2019 for the canopy extraction methods: 2-pixel erosion (2PE) (turquoise), edge detection (dark blue), vegetation segmentation (VS) (coral), and RGB binary masking (RGB-BM) (brick red).

#### *3.3. Orchard Water Status Estimation*

The CWSI\_T100% values were substantially higher than the CWSI\_T33% values per MC, per date, and per canopy extraction method, and they mirrored the trends found in the canopy temperature calculated using T100% and T33% (Figure 7). The average difference between the CWSI\_100% and CWSI\_T33% values for each canopy extraction method was as follows: 0.28 (ED), 0.30 (2PE), 0.67 (RGB-BM), and 0.68 (VS). Within the CWSI\_T100% dataset, minimal differences were recorded between the 2PE and ED methods (0.02), while large differences were calculated between the 2PE and VS methods (0.42). In the CWSI\_T33% dataset, no difference was found between the 2PE and ED methods, and a difference of 0.03 was calculated between the VS and 2PE methods.

**Figure 7.** Crop water status index (CWSI) with Tcanopy (◦C) calculated using the average 100% (CWSI\_T100%) and the average of the coolest 33% (CWSI\_T33%) of canopy pixels. Twet = lowest 5% of canopy pixels, and Tdry = Tair + 2 ◦C. Values per management cell (MC) between 21 July and 26 August 2019 for the canopy extraction methods: 2-pixel erosion (2PE) (turquoise), edge detection (ED) (dark blue), vegetation segmentation (VS) (coral), and RGB binary masking (RGB-BM) (brick red). The table insert shows the air temperature (Tair (◦C)) values.
