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68 WINES&VINES June 2018 GRAPEGROWING WINE EAST W ine composition and quality are related to several vineyard vari- ables that can be observed and managed in the field. However, vineyards are variable with respect to soil tex- ture, moisture and depth and other variables such as organic matter, cation-exchange capac- ity and major and minor elements. As a result, vineyards also vary in vigor, yield, and fruit composition. Such variability within and among vineyards has been recognized for cen- turies and can be ascribed to a combination of soil, local climate, vine vigor, and other factors that ultimately affect wine quality. This is re- ferred to as the terroir effect. 34 Traditional viticulture aims to maximize wine quality by tailoring variety selection and cultural practices to this local terroir. Terroir can be characterized in the field by mapping bedrock, soil, and vineyard meso-climate, and, at a finer level,by mapping variables such as soil moisture, vine water status, yield compo- nents and berry composition. Much of this mapping must be ground-based (including below the soil surface in trenches and drill holes). However, many of these variables now can be measured or estimated from the air using standard aircraft or satellite remote sens- ing technology. Research in Ontario vineyards since 1998 has produced spatial maps and quantified spatial variability in soil composition, vine elemental composition, vigor, vine water sta- tus, vine winter hardiness, yield and berry composition. 15, 16, 25-28 These variables have been analyzed to determine relevant spatial relationships among them. Maps showing clear zones of different vigor, yield and vine water status have allowed wineries to produce wines from these unique zones that are dif- ferent chemically and sensorially. 15, 16 Also, researchers have accumulated evidence of relationships between vine vigor and vine water status vs. wine sensory properties, and by doing so, with efforts of others elsewhere, 34 have helped explain the essence of the terroir concept. Tools and methods have been developed relatively recently to observe and measure this inter- and intra-vineyard variation, and then to use the information for more efficient vine- yard management. 5 These tools and methods can be used for the implementation of "preci- sion viticulture" techniques. Simply defined, precision agriculture in general is informed agricultural management at a fine spatial scale. Its purpose is to enable targeted crop manage- ment due to the understanding and accurate mapping of the variations of crop or canopy properties of interest. The implementation of precision viticulture involves three main steps: 1. Observation of vineyard variables asso- ciated with vineyard performance (data collection); 2. Interpretation and evaluation of the data; 3. Implementation of targeted vineyard management practices and/or selective harvesting strategies. 5 Targeted vineyard-management practices might include timing and rate of application of fertilizer, water, pesticide or herbicide Viticultural Mapping by UAVs, Part 1 Unmanned aerial vehicles provide data for precision viticulture By Andrew G. Reynolds, Ralph Brown, Marilyne Jollineau, Adam Shemrock, Elena Kotsaki, Hyun-Suk Lee, Mehdi Shabanian and Patrick Kelly KEY POINTS The images produced by unmanned aerial vehicles (UAVs), or drones, have a higher spatial resolution than those produced by satellites and conventional aircraft. UAVs have other advantages: a higher flexibility of use, lower operational costs, and they are not affected by cloud cover. The potential application of the acquired data should determine which remote sensing platform is chosen. When the goal is accurate mapping of intra-vineyard variability so that precision viticulture practices can be implemented, UAVs are the best choice. UAVs equipped with appropriate sensors can collect useful information such as leaf temperature, vine water status, and canopy vigor. Those sensors can gather thermal, visible, hyperspectral and/or multispectral images. Hyperspectral sensors, for example, can gather a broader range of wavelengths; a thermal camera can gather image data to determine canopy variables such as water stress. Acquired images are first orthorectified to remove the effects of tilt and terrain. The raw images are also georeferenced using ground control points previously measured with a ground-based device or UAV's onboard GPS. At that point, images can be mosaicked, or stitched, together using georeferenced-based stitching software. EDITOR'S NOTE This is the first installment of a two- part series on using unmanned aerial vehicles (UAV) to obtain data to help vineyards implement precision viticul- ture. The authors look at the different UAV platforms, hardware, sensors and image processing. The second article will review the use of UAVs in viticul- ture and will include the results of a study done in Ontario vineyards.