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June 2015 P R A C T I C A L W I N E R Y & V I N E YA R D 65 G R A P E G R O W I N G Napa Fermentation Supplies is proud to be a West Coast Kärcher distributor since 1989. Our prices are the lowest and we have the complete product line available. We are also a Kärcher repair facility. Kärcher state-of-the-art high-pressure washers are distinguished by infinitely variable operating pressure, water volume and temperature control, as well as precise chemical metering. Heated models incorporate a 90%+ fuel efficient burner system, low fuel shut-off and complete machine shut-off at the trigger gun for maximum safety and performance. NAPA FERMENTATION SUPPLIES Napa Fermentation Supplies (707) 255-6372 • napafermentation.com Mapping vineyard vigor Differences in soil across a vineyard block often contribute to growth dif- ferences in vines as observed in the canopy. Vegetation index maps, often referred to as "vigor maps," are helpful tools for understanding differences in relative vigor across a mature vineyard block. Differences in vigor may be due to numerous factors, including changes in soil characteristics. Normalized difference vegetation index (NDVI) mapping is one of the most commonly used tools for tracking differences in vegetative growth across a vineyard (Figure 2). NDVI images provide a snapshot in time (such as mid-summer) when the relative canopy size and health can be compared within a vineyard block. Vines or areas of low NDVI will use less water, drying the soil at a slower rate than vines or areas with a higher NDVI. Additional, low-tech measures can be taken to verify growth differences observed from NDVI maps, including dormant pruning weights of vines and visual observation. Pre-plant considerations Uniform vine growth is desired within a vineyard block. Variability of soil across a vineyard site should be considered when designing the layout of vineyard blocks and irrigation. In general, larger vineyard blocks are more economical to establish and manage, therefore it is not always practical to divide blocks by soil type. However, irrigation design in the pre- plant phase allows a grower to custom- ize a system across a block, such as developing separate irrigation zones to address differences in soil water-holding capacity. It is also useful to have histori- cal photos or satellite images and crop use information to identify areas of the site that may have had large areas of soil disturbed (uprooted trees, trenching for pipelines or compacted roadways). Choosing sensor locations in an existing vineyard The goal when choosing sensor locations in an existing vineyard block is to locate an area of the vineyard with soil that best rep- resents the majority of the irrigation block. Placement of sensors in the outlying soils of lowest or highest water hold- ing capacity can result in soil moisture readings that lead to either excess or under-irrigation. Supplemental irrigation may be needed in the weakest area of the vineyard block. The series of soil cores in Figure 3 show the difference in soil across a block of Cabernet Sauvignon (Figure 2, block G). The soil core from the lowest elevation (A) is from the center of the high-vigor swale area on the west side of the block. Figure 5. A typical soil-moisture sensor installation shows the placement distance about 4-6 inches from a drip emitter. Some trial and error may be needed to determine ideal distance from the emitter to correlate soil moisture readings with plant water stress measurements. 415 293 5700 | bararch.com W I N E R I E S C L U B H O U S E S R E S O R T S C U S T O M H O M E S L AW W I N E R Y PA S O R O B L E S , C A