Alternative Trellising Systems for Chardonnay and Merlot Vineyards in the Central Coast

AVF Proj. ID: 179 / /Cat.: ,
Primary Investigator(s): Nick Dokoozlian, Larry Bettigaby

A four-year study (1998-2001) compared the long-term performance of bilateral cordon trained, spur pruned Chardonnay and Merlot grapevines trellised to the vertically shoot positioned trellis system (VSP), the vertically divided Smart-Henry trellis system (SH) and the vertically separated Smart-Dyson trellis system (SD). Vine vigor at the site was moderate. Compared to the VSP, the SH and SD systems reduced canopy density and improved fruit zone microclimate. SD and SH vines had fewer leaf layer numbers and greater amounts of sunlight in their fruiting zones compared to VSP vines. Primary, lateral and total leaf areas per vine were similar among the treatments, indicating that differences in canopy density were a result of canopy division or separation along with an increase in total canopy volume available for foliage distribution. Over the course of the study the yield of SH and SD vines was generally10%to 15%greater compared to VSP vines. Pruning weight per vine and the yield:pruning weight ratios were generally similar among the treatments in both cultivars. In the first year of evaluation fruit on downward-oriented shoots on the SH system ripened more slowly compared to shoots oriented upward, but these differences diminished as the yield of the lower fruiting zone in this system declined. No significant difference in fruit ripening was observed due to shoot orientation in the SD. Few differences in combined fruit (upper and lower canopies) soluble solids, titratable acidity and pH were observed among the treatments in either cultivar over the four-year period. Fruit and wine color (Merlot) were improved in the SD and SH treatments, and wines from these treatments in the Merlot were preferred over the VSP system in three of the four years of the experiment. We found that SD and SH trellis systems significantly improved both yield and fruit composition compared to the VSP system. SD is preferred over SH based on ease of establishment and culture, as well as long-term productivity; both vigor and productivity of downward trained shoots in the SH declined over the course of the study.

PDF: Alternative Trellising Systems for Chardonnay and Merlot Vineyards in the Central Coast

Influence of Row Orientation and Cluster Exposure to Sunlight on the Microclimate and Composition of Cabernet Sauvignon Fruits

AVF Proj. ID: 196 / /Cat.: ,
Primary Investigator(s): Nick Dokoozlianby

The effects of row orientation and canopy density (as defined by leaf layer number or LLN in the fruit zone) on the fruit zone microclimate and composition of Cabernet Sauvignon was studied in a commercial vineyard located near Oakville, CA in the Napa Valley. A mature Cabernet Sauvignon vineyard with adjacent blocks of north-south and east-west oriented rows was used. Fruit zone microclimate was manipulated within each row orientation immediately after berry set by varying the amounts of basal leaf and lateral shoot removal in the fruiting zone (primary shoot basal nodes 1-5). The following four treatments were applied: 1. untreated control; 2. remove basal leaves only; 3. remove lateral shoots only; 4. remove basal leaves and lateral shoots. The LLN values created by these treatments ranged from 0 (complete basal leaf and lateral shoot removal) to approximately 2.5 (untreated) in the fruit zone. A negative, near linear relationship was found between fruit zone LLN and the percentage of exterior clusters in both row orientations. The percentage of exterior clusters ranged from approximately 30%(LLN~2.5) to over 90%(LLN=0). Berry temperature and cluster sunlight exposure increased as LLN in the fruiting zone declined. Fully exposed clusters (LLN=0) on the south (E-W rows) and west (N-S rows) sides of the canopy had the greatest mid-day berry temperatures in the experiment, averaging approximately 6C greater than ambient air temperature by late afternoon on most sunny days. Berry weight was generally least for fully exposed berries and greatest for shaded berries, regardless of row orientation. In N-S rows, soluble solids were lowest in fully exposed berries and increased slightly as LLN increased. No trend was observed between cluster exposure and soluble solids levels in E-W oriented rows. Titratable acidity and malic acid content generally declined as cluster exposure increased, while juice pH increased slightly as cluster exposure increased. Observed differences in skin anthocyanins in N-S rows reflected differences in berry temperature resulting from sunlight exposure; fully exposed clusters on the west exposure had lower anthocyanin concentrations compared to partially shaded clusters. No strong trend in berry color development due to cluster exposure was observed in E-W rows, although fruit in E-W rows generally had greater color development for all exposure levels compared to fruit in N-S rows. The results indicate that berry exposure to direct sunlight during the afternoon (west or south facing exposures) leads to elevated berry temperatures and undesirable reductions in berry color and acidity. Chemical and sensory analyses of experimental wines produced from each treatment will be completed during the spring of 2002.

PDF: Influence of Row Orientation and Cluster Exposure to Sunlight on the Microclimate and Composition of Cabernet Sauvignon Fruits

Wine Grape Trellising and Vine Spacing Studies

AVF Proj. ID: 197 / /Cat.: ,
Primary Investigator(s): Nick Dokoozlianby

Three separate studies were continued in 2001 to examine the effects of trellis/training system and in-row spacing on the yield, growth and fruit composition of wine grapes in the San Joaquin Valley. This progress report summarizes the information generated since data collection was initiated in each trial. In the first experiment, Chardonnay grapevines (Clone 4 grafted to 5C rootstock) were trained to six different systems trellis/training systems (Sprawl, VSP, Wye, Lyre, Smart-Henry and Smart-Dyson) at the Kearney Agricultural Center in Parlier. The horizontally divided Wye and Lyre systems produced the most clusters per vine, the Sprawl was intermediate, while the VSP, Smart-Dyson and Smart-Henry produced the fewest. However, when fruitfulness was expressed per foot cordon length, vines trellised to the Sprawl, VSP and Smart-Dyson were more fruitful than the remaining systems. Total yield per vine was generally similar among the trellising treatments, except that vines trained to the Lyre and Wye produced significantly greater yields than VSP vines. Based on standard industry row spacing for each treatment, estimated yields per acre ranged from 12.4 tons per acre for the Smart-Henry to 10.4 tons per acre for the California Sprawl. Sprawl and Smart-Dyson vines produced larger berries than the other treatments, while soluble solids, titratable acidity and juice pH were generally similar. Sprawl vines produced the greatest pruning weights per vine and per foot cordon length, the greatest mean cane weight, and the lowest yield:pruning weight ratio in the trial. In contrast, Wye and Smart-Henry vines had the lowest pruning weights per vine and per foot cordon length, as well as the greatest yield:pruning weight ratios in the trial. Wye vines had the greatest amount of light with the fruiting zone at mid-day, while VSP vines had the least. Canopy characteristics within the fruit zone were generally similar among the treatments except that canopy density or leaf layer number (LLN) was much greater for Sprawl vines compared to the remaining treatments. A separate experiment at the Kearney Agricultural Center examined the effects of in-row spacing and training system on vine performance and canopy characteristics. Syrah grapevines (UC Clone 7 grafted to 5C rootstock) were planted either 4, 6, 8, 10 or 12 feet between vines in the row and trained to two training systems (bilateral vs. quadrilateral cordon). Nearly all bilateral cordon trained vines were trained fully in 1999, while the portion of fully trained quadrilateral cordon vines dropped linearly as in-row spacing increased. All vines were fully trained in 2000. Cordon and trunk diameters revealed that 4 and 6 foot in-row spacing reduced initial vine size compared to wider spacing, while LLN also decreased as in-row spacing increased. Productivity per acre was similar among the spacing treatments when bilateral cordon training was utilized, while yield per acre declined slightly as in-row spacing was increased for quadrilateral cordon trained vines. No significant differences in berry size and fruit composition were observed among the treatments at harvest. A trial was also established near Lodi in a commercial vineyard to examine the effects of in-row spacing on vine performance and canopy characteristics. Syrah grapevines (UC Clone 7 grafted to 5C rootstock) were planted either 5, 7, 9, 11 or 13 feet apart in the row. Clusters per vine and total yield increased linearly with in-row spacing, while both parameters declined with increased in-row spacing when expressed per foot row or cordon length. Point quadrant parameters indicated that canopy density declined as in-row spacing increased. Total tons per acre were greatest when the space between vines ranged between 7 and 9 feet. No significant differences in berry size or fruit composition were observed among the treatments at harvest.

Influence of Row Orientation and Cluster Exposure to Sunlight on the Microclimate and Composition of Cabernet Sauvignon Fruits

AVF Proj. ID: 134 / /Cat.: ,
Primary Investigator(s): Nick Dokoozlianby

The effects of row orientation and cluster exposure to sunlight on the microclimate and fruit composition of Cabernet Sauvignon was studied in a commercial vineyard in the Napa Valley. Eight clusters per vine (one cluster/shoot) were selected for use immediately after berry set. Clusters were divided into two groups of four, with each group located on either the morning exposed (north or east side of the vine row, respectively, for east-west and north-south oriented rows) or afternoon exposed (south or west side of the vine row, respectively, for east-west and north-south oriented rows) portion of the vine row. Four cluster sunlight exposure categories were established: (1) full exposure, (2) moderate to high exposure, (3) moderate to low exposure, and (4) shaded. A positive, near linear relationship was found between berry temperature and PAR incident to the cluster surface following veraison. Fully exposed clusters on the south (E-W rows) and west (N-S rows) sides of the canopy had the greatest mid-day berry temperatures in the experiment. Berry weight was generally greatest for fully exposed berries and least for shaded berries, regardless of row orientation. Soluble solids followed a similar trend, with the lowest oBrix found in clusters on the east side of N-S rows and the highest clusters grown on the south of E-W rows. Titratable acidity was generally similar among exposure treatments, while malate levels in shaded fruits were significantly greater compared to exposed fruits. Observed differences in both skin anthocyanins and total phenolics among the treatments reflected differences in berry temperature resulting from sunlight exposure; fully exposed clusters on the south (E-W rows) and west (N-S rows) exposures had lower anthocyanin concentrations compared to shaded clusters. The results indicate that berry exposure to direct sunlight during the afternoon (west or south facing exposures) leads to elevated berry temperatures and undesirable reductions in berry color, total phenolics and malate.

PDF: Influence of Row Orientation and Cluster Exposure to Sunlight on the Microclimate and Composition of Cabernet Sauvignon Fruits

Wine Grape Trellising and Vine Spacing Studies

AVF Proj. ID: 135 / /Cat.: ,
Primary Investigator(s): Nick Dokoozlianby

In the first experiment, Chardonnay grapevines (Clone 4 grafted to 5C rootstock) were trained to six different systems trellis/training systems (Sprawl, VSP, Wye, Lyre, Smart-Henry and Smart-Dyson) at the Kearney Agricultural Center in Parlier. The horizontally divided Wye and Lyre systems produced the most clusters per vine, the Sprawl was intermediate, while the VSP, Smart-Dyson and Smart-Henry produced the fewest. However, when fruitfulness was expressed per foot cordon length, vines trellised to the Sprawl, VSP and Smart-Dyson were more fruitful than the remaining systems. Total yield per vine was generally similar among the trellising treatments, except that vines trained to the Lyre and Wye produced significantly greater yields than VSP vines. Based on standard industry row spacing for each treatment, estimated yields per acre ranged from 12.4 tons per acre for the Smart-Henry to 10.5 tons per acre for the California Sprawl. Sprawl and Smart-Dyson vines produced larger berries than the other treatments, while soluble solids, titratable acidity and juice pH were similar. Sprawl vines produced the greatest pruning weights per vine and per foot cordon length, the greatest mean cane weight, and the lowest yield:pruning weight ratio in the trial. In contrast, Wye and Smart-Henry vines had the lowest pruning weights per vine and per foot cordon length, as well as the greatest yield: pruning weight ratios in the trial.

A separate experiment at the Kearney Agricultural Center examined the effects of in-row spacing and training system on vine performance and canopy characteristics. Syrah grapevines (UC Clone 7 grafted to 5C rootstock) were planted either 4, 6, 8, 10 or 12 feet between vines in the row and trained to two training systems (bilateral vs. quadrilateral cordon). Nearly all bilateral cordon trained vines were trained fully in 1999, while the portion of fully trained quadrilateral cordon vines dropped linearly as in-row spacing increased. About 80%of the cordon wire was filled when quadrilateral vines were spaced 4 feet in the row, but this dropped to less than 40%when in-row spacing was 12 feet. Cordon and trunk diameters revealed that 4 and 6 foot in-row spacing reduced initial vine size compared to wider spacing, while canopy density (leaf layer number or LLN) also decreased as in-row spacing increased. Productivity per acre was maximized when in-row spacing was 6 to 8 feet for bilateral cordon vines. Maximum productivity per acre for quadrilateral vines was obtained with an in-row spacing of 4 feet, and tons per acre declined steadily as in-row spacing increased. No significant differences in berry size and fruit composition were observed among the treatments at harvest.

A trial was also established near Lodi in a commercial vineyard to examine the effects of in-row spacing on vine performance and canopy characteristics. Syrah grapevines (UC Clone 7 grafted to 5C rootstock) were planted either 5, 7, 9, 11 or 13 feet apart in the row. Clusters per vine and total yield increased linearly with in-row spacing, while both parameters declined with increased in-row spacing when expressed per foot row or cordon length. Point quadrant parameters indicated that canopy density declined as in-row spacing increased. Total tons per acre were greatest when the space between vines ranged between 7 and 9 feet. No significant differences in berry size or fruit composition were observed among the treatments at harvest. Wines from all three trials will be evaluated in the spring of 2001.

PDF: Wine Grape Trellising and Vine Spacing Studies

Use of Aerial Imaging to Evaluate Vineyard Canopy Variability

AVF Proj. ID: 154 / /Cat.: ,
Primary Investigator(s): Jim Wolpertby

The RVI, NDVI, and PVI were shown to be correlated with VSP canopy density using both field spectroscopy data at the vine scale, and aerial image analysis at the vineyard scale. The ratio based indices (RVI and NDVI) were shown to have similar information contents but the RVI was found to be more linearly related to canopy density over a broad range of values, and thus more desirable for vineyard remote sensing applications. The PVI was found to be ineffective at reducing remote sensing measurement noise and accordingly, showed the poorest correlation with canopy density values. Results from this analysis corroborate with findings from investigators in woodland and forest environments, and provide evidence of the complex nature of vineyard scene reflectance properties.

The ratio vegetation index was shown to be linearly related to canopy density at 100%and less than complete canopy cover. It was also shown that the RVI response at less than complete canopy cover was less sensitive to increasing canopy density than that taken at complete cover. This linear response across a broad range of LAI values (1-5) is surprising in light of findings reported by other investigators in agronomic systems. This may suggest that alternate factors other than variation in percent vegetation cover, such as spectral background influences, may be driving the VI to canopy density relationship in VSP vineyard systems.

Results reported by investigators in semi-arid woodlands and forest communities’ show that shadow influences on scene reflectance play a significant role in determining the VI to vegetation parameter relationship. VSP vineyards have discontinuous canopies with moderate levels of percent cover. Vine row geometry leads to variation in shadow scene proportions that vary as a function of sun azimuth and zenith angles in relation to row orientation. Moreover, the sensitivity of canopy reflectance on spectral background variation was found to be greatest in canopies with intermediate covers (50-60%cover) because of the prevalence of soil-vegetation spectral interactions at these levels of canopy cover. This evidence may suggest that VSP vineyard scene reflectance more closely approximates that of semi-arid woodland systems as opposed to continuous canopy agronomic systems, due to potential shading effects, moderate percent vegetation cover, and the discontinuous nature of VSP canopies.

PDF: Use of Aerial Imaging to Evaluate Vineyard Canopy Variability

Use of Aerial Imaging to Evaluate Vineyard Canopy Variability

AVF Proj. ID: 43 / /Cat.: ,
Primary Investigator(s): James Wolpertby

The RVI, NDVI, and PVI were shown to be correlated with VSP canopy density using both field spectroscopy data at the vine scale, and aerial image analysis at the vineyard scale. The ratio based indices (RVI and NDVI) were shown to have similar information contents but the RVI was found to be more linearly related to canopy density over a broad range of values, and thus more desirable for vineyard remote sensing applications. The PVI was found to be ineffective at reducing remote sensing measurement noise and accordingly, showed the poorest correlation with canopy density values. Results from this analysis corroborate with findings from investigators in woodland and forest environments, and provide evidence of the complex nature of vineyard scene reflectance properties. The ratio vegetation index was shown to be linearly related to canopy density at 100%and less than complete canopy cover. It was also shown that the RVI response at less than complete canopy cover was less sensitive to increasing canopy density than that taken at complete cover. This linear response across a broad range of LAI values (1-5) is surprising in light of findings reported by other investigators in agronomic systems. This may suggest that alternate factors other than variation in percent vegetation cover, such as spectral background influences, may be driving the VI to canopy density relationship in VSP vineyard systems. Results reported by investigators in semi-arid woodlands and forest communities’ show that shadow influences on scene reflectance play a significant role in determining the VI to vegetation parameter relationship. VSP vineyards have discontinuous canopies with moderate levels of percent cover. Vine row geometry leads to variation in shadow scene proportions that vary as a function of sun azimuth and zenith angles in relation to row orientation. Moreover, the sensitivity of canopy reflectance on spectral background variation was found to be greatest in canopies with intermediate covers (50-60%cover) because of the prevalence of soil-vegetation spectral interactions at these levels of canopy cover. This evidence may suggest that VSP vineyard scene reflectance more closely approximates that of semi-arid woodland systems as opposed to continuous canopy agronomic systems, due to potential shading effects, moderate percent vegetation cover, and the discontinuous nature of VSP canopies.

Wine Grape Trellising and Vine Spacing Studies

AVF Proj. ID: 46 / /Cat.: ,
Primary Investigator(s): Nick Dokoozlianby

In the first experiment, Chardonnay grapevines (Clone 4 grafted to 5C rootstock) were trained to six different systems trellis/training systems (Sprawl, VSP, Wye, Lyre, Smart-Henry and Smart-Dyson) at the Kearney Agricultural Center in Parlier. The horizontally divided Wye and Lyre systems produced the most clusters per vine, the Sprawl was intermediate, while the VSP, Smart-Dyson and Smart-Henry produced the fewest. However, when fruitfulness was expressed per foot cordon length, vines trellised to the Sprawl, VSP and Smart-Dyson were more fruitful than the remaining systems. Total yield per vine was generally similar among the trellising treatments, except that vines trained to the Lyre and Wye produced significantly greater yields than VSP vines. Based on standard industry row spacing for each treatment, estimated yields per acre ranged from 12.4 tons per acre for the Smart-Henry to 10.5 tons per acre for the California Sprawl. Sprawl and Smart-Dyson vines produced larger berries than the other treatments, while soluble solids, titratable acidity and juice pH were similar. Sprawl vines produced the greatest pruning weights per vine and per foot cordon length, the greatest mean cane weight, and the lowest yield:pruning weight ratio in the trial. In contrast, Wye and Smart-Henry vines had the lowest pruning weights per vine and per foot cordon length, as well as the greatest yield: pruning weight ratios in the trial. A separate experiment at the Kearney Agricultural Center examined the effects of in-row spacing and training system on vine performance and canopy characteristics. Syrah grapevines (UC Clone 7 grafted to 5C rootstock) were planted either 4, 6, 8, 10 or 12 feet between vines in the row and trained to two training systems (bilateral vs. quadrilateral cordon). Nearly all bilateral cordon trained vines were trained fully in 1999, while the portion of fully trained quadrilateral cordon vines dropped linearly as in-row spacing increased. About 80%of the cordon wire was filled when quadrilateral vines were spaced 4 feet in the row, but this dropped to less than 40%when in-row spacing was 12 feet. Cordon and trunk diameters revealed that 4 and 6 foot in-row spacing reduced initial vine size compared to wider spacing, while canopy density (leaf layer number or LLN) also decreased as in-row spacing increased. Productivity per acre was maximized when in-row spacing was 6 to 8 feet for bilateral cordon vines. Maximum productivity per acre for quadrilateral vines was obtained with an in-row spacing of 4 feet, and tons per acre declined steadily as in-row spacing increased. No significant differences in berry size and fruit composition were observed among the treatments at harvest. A trial was also established near Lodi in a commercial vineyard to examine the effects of in-row spacing on vine performance and canopy characteristics. Syrah grapevines (UC Clone 7 grafted to 5C rootstock) were planted either 5, 7, 9, 11 or 13 feet apart in the row. Clusters per vine and total yield increased linearly with in-row spacing, while both parameters declined with increased in-row spacing when expressed per foot row or cordon length. Point quadrant parameters indicated that canopy density declined as in-row spacing increased. Total tons per acre were greatest when the space between vines ranged between 7 and 9 feet. No significant differences in berry size or fruit composition were observed among the treatments at harvest. Wines from all three trials will be evaluated in the spring of 2001.

Alternative Trellising Systems for Chardonnay and Merlot Vineyards in the Central Coast

AVF Proj. ID: 9903 / /Cat.: ,
Primary Investigator(s): Nick Dokoozlianby

The purpose of this study is to compare the performance of bilateral cordon trained, spur pruned Chardonnay and Merlot grapevines trellised to the vertically shoot positioned trellis system (VSP), the Smart-Henry trellis system (SH) and the Smart-Dyson trellis system (SD) in the Salinas Valley of California. Primary leaf size, as well as primary, lateral and total leaf area per vine, did not differ significantly among the treatments. VSP vines had greater leaf layer numbers in the fruiting zone compared to SD and SH vines, and these treatments had greater amounts of sunlight in the fruit zone compared to the VSP treatment. Vine yield components were similar among the treatments in both cultivars. Compared to upward-oriented canopies, trends toward reduced yields for downward-oriented canopies were observed in Chardonnay, while the opposite was true for Merlot. Pruning weights and pruning weight ratios were similar among the treatments in both cultivars. Fruit on downward-oriented shoots on the SH and SD systems generally ripened more slowly compared to shoots oriented upward. At harvest, however, no significant differences in combined fruit (upper and lower canopies) soluble solids, titratable acidity and pH were observed among the treatments in either cultivar. Wine lots made from each treatment will be evaluated in 2000.

Use of Aerial Imaging to Evaluate Vineyard Canopy Variability

AVF Proj. ID: 9945 / /Cat.: ,
Primary Investigator(s): James Wolpertby

A good deal of attention has been paid to the light environment of grapevine canopies. Research on the physiological responses to light microclimate has been extensive. Studies have shown that vine yield, berry composition, and wine quality all improve with increased fruit and leaf exposure to sunlight (Dokoozlian 1990; Kliewer 1982; Smart 1985). From these findings have come the impetus for many of the canopy management practices used today. These include shoot positioning, hedging, leaf thinning, and canopy division. These activities are performed in order to optimize the canopy light microclimate environments. Grapevine light microclimate is effected by the structure and density of the canopy components including leaves, shoots, and woody material. Measurements of the grapevine canopy are difficult because of the high spatial and temporal variation within the canopy. Indices pertinent to isolated plants and row crops have been applied to grapevines. These measurements include characterizing canopies as geometrical shapes with given height, length, width, area, and volume measurements. A second approach measures leaf area and leaf density on a per vine, unit length, or unit area basis. Leaf area index (LAI; leaf area per unit of soil surface area) is one of the commonly used indices of this type. Measurements of leaf area and leaf area density (LAD; leaf area per unit volume) are used as indicators of vine vigor and as inputs into models of evapotranspiration, whole-vine photosynthesis, or sunlight penetration. Measurements of leaf area are time consuming and labor intensive because of the inherent variability found within a vine and on a larger scale within a vineyard. Some methods are destructive and can not be applied to different treatments. There are a number of techniques that are based on an interactive relationship between canopy structure and radiation interception. These techniques measure the gap fraction, i.e. the proportion of light which is not blocked by foliage in a range of azimuthal directions. Leaf area is estimated using mathematical models with the gap fraction as an input parameter. These mathematical models often assume a random foliage distribution which rarely occurs (Ollat, 1998). In addition, light sensors need to be placed within and above the grapevine canopy in order to measure the gap fraction. This limits the scale of sampling and its utilization within an commercial vineyard setting. There is a need for alternate methods of estimating leaf area that are both cost effective and accurate. 21 Project Title: Use of Aerial Imaging to Evaluate Vineyard Canopy Variability (Continued) Advances in the field remote sensing present possible methods for evaluating vine canopy characteristics including leaf area density and canopy architecture. One method involves the use of aerial image collection and analysis. The most commonly available method of aerial image acquisition is the use of four-band, digital, multi-spectral image data that are collected by an airplane (or satellite) and processed to produce a measure (vegetation index) of canopy density. Calculating this index is based on the principle that photosynthetically active vegetation shows high absorption of incident sunlight in the visible red (R) wavelengths and strong reflectance in the near-infrared wavelengths (NIR). These spectral properties are distinctive from that of soil and water, the other two predominant landscape features. There are many useful algorithms for computing vegetation indices with the most common falling into a class of ratio indices [RVI = NIR/R; NDVI = (NTR-R)/(NIR+R)]. Vegetation indices derived from these two spectral bands have been shown to correlate highly with green leaf area index, chlorophyll content, photosynthetically active biomass, vegetation density, photo synthetic rate, percent ground cover by vegetation, and grain or forage yield (Weigand et al. 1991). Studies utilizing this technology have been performed mostly in closed canopy systems such as grasslands and contiguous forest. No published study has been found where the system was a vertically shoot positioned vineyard. Vineyards do not exhibit a closed canopy system. A significant percentage of a vineyard is comprised of vineyard middles and has the spectral properties of bare soil and/ or cover crops. The influence of varying spectral backgrounds has not been studied in the context of vineyard systems. In addition, grapevine foliage distribution is not entirely understood. Canopy leaf area, density, and structure are managed within the confines of given trellising systems using practices such as shoot positioning, leaf pulling, and hedging. The spectral response, if any, of changing the canopy density using any of these practices is not understood. These factors must be taken into account when applying remote sensing technologies to vineyard management.