Grape Canopy Research Articles

Hail netting changes to spray droplets and patterns in grape canopies

While hail netting in vineyards provides effective protection to wine grapes (Vitis vinifera L.) from hail, pests, and bird damage, it may also affect the spray efficacy. This study tested the interaction between hail netting and location within the canopy in determining spray droplet characteristics. Two grape cultivars (Petite Sirah FPS 04 and Touriga Nacional FPS 05) grafted onto 1103P rootstock were examined to assess spray coverage, droplet size distribution, and deposition within grapevine canopies under netted and unnetted conditions. Spray droplets were measured using spray cards placed at five locations within the canopy. Significant interactions were observed primarily at the base of the canopy directly above the cordon, where grape clusters are most concentrated. Unnetted Touriga Nacional exhibited higher spray coverage compared to Petite Sirah, attributed to its looser cluster structure. Hail netting standardized all parameters across both cultivars, mitigating the influence of canopy and cluster differences. Hail netting created smaller, uniformly distributed droplets within the canopy, an essential characteristic of effective pest and disease control. Conversely, without netting, larger droplets were unevenly distributed, predominantly settling on the outer and lower canopy sections. Hail netting also maintained deposit densities within recommended ranges, supporting effective pest and disease management without compromising spray coverage. The consistent spray coverage achieved with hail netting across all canopy locations highlights its role in improving application uniformity and grapevine health, leading to evenly ripened, high-quality fruit. Contrary to the perceived risk of reducing spray efficacy, hail netting appears to enhance vineyard spraying outcomes, potentially offsetting netting costs.

Planococcus ficus (Hemiptera: Pseudococcidae) movement and demography: methods for generating cohorts for laboratory studies.

Planococcus ficus (Signoret) is a worldwide pest of grapevine. Mealybugs overwinter under bark and move into the grape canopy as the season progresses. Because crawlers are more active than later stages, mealybug movement behavior is likely to be stage specific. To quantify P. ficus demography and movement behavior, a series of laboratory experiments were conducted. First, P. ficus populations were monitored on grapevine seedlings to describe survival, change in size, timing of male pupation, and timing of oviposition over a 6-wk period. Subsequently, cohorts of mealybugs were generated by infesting grapevines with crawlers and holding infested grapevines for a specified duration of 0 (crawlers), 1, 2, 3, or 4 wk. Crawlers (0-wk) were more likely to move upwards and towards a light source, than all other age cohorts tested. Further, mealybugs from 4-wk-old cohorts were more likely to move downward than all other age cohorts tested. Results suggest that crawlers are more likely to move to the top of grapevines by moving upwards and orienting towards either the sun or the moon than all other age cohorts tested, whereas older gravid females are more likely to move downward. Passive movement of mealybugs on farm machinery or animals requires surviving a host free period. To quantify risk of passive movement, establishment rates and effects of starvation on each age cohort were quantified. Larger and older mealybugs were more likely to establish on grapevines than smaller and younger mealybugs. Further, mealybug longevity in absence of food was greater for older cohorts compared to younger cohorts. Crawlers survived an average of 2 days without food, whereas females from 4-wk-old cohorts survived for an average of 11 days without food. Further, 70% of starved females from 4-wk-old cohorts deposited fertile eggs. In the absence of food, some mealybugs from cohorts aged 2-, 3-, and 4-wk formed pupa with viable males emerging. Adult males from starved nymphs lived for an average of 3 days post-emergence. Results provide methods for producing cohorts of mealybugs of predictable size and stage and provides insight into P. ficus demography and movement behavior.

Feature Pyramid Network based Proximal Vine Canopy Segmentation

With the widening of the Agriculture 4.0 era, the use of autonomous robots in the agriculture field is becoming a priority. The key component of such an autonomous, often multi-robot system is the perception of the environment, which is based on 2D and 3D cameras. A base processing part of the 2D images is the segmentation of different zones in the images. This is the case also in the vineyards where in order to process complex plant canopies, segmenting the parts of the image containing the area of interest is a part of the pre-processing chain. In this work, we present a Feature Pyramid Network-based grape canopy segmentation method, which has great potential to create a segmentation mask, containing only the leaves and fruits of interest. We conducted our tests in different vineyards and we also obtained the above state-of-the-art segmentation results on public and custom datasets.

New Aspects of In Situ Measurements for Downy Mildew Forecasting.

Downy mildew is, globally, one of the most significant diseases in viticulture. Control of this pathogen is achieved through fungicide application. However, due to restrictions (from upcoming regulations) and growing environmental conscientiousness, it is critical to continuously enhance forecasting models to reduce fungicide application. Infection potential has traditionally been based on a 50 h–degree calculation (temperature multiplied by leaf wetness duration) measured by weather stations; the main climatic parameters for forecast modelling are temperature, relative humidity, and leaf wetness. This study took these parameters measured by a weather station and compared them with the same parameters measured inside a grape canopy. The study showed that the temperature readings by the weather station compared to inside the canopy recorded differences during the day but not at night; the relative humidity showed significant differences during both daytime and night; leaf wetness showed the highest differences and was statistically significant during both daytime and night. In conclusion, the measurement differences between inside of the canopy and at the weather station have significant impacts on the precision of forecasting models. Thus, using data from inside of a canopy for the prediction should lead to even less fungicide applications.

Assessment of Three Commercial Over-the-Row Sprayer Technologies in Eastern Washington Vineyards

Washington wine grape growers are rapidly adopting vineyard management technologies such as mechanical pruners and harvesters but have been slower to adopt new chemical application technologies. Therefore, this study was aimed at generating technical information about commercial over-the-row sprayers deposition and drift, which could be used by growers during sprayer selection and optimization for different vineyard systems and wine grape canopies. Three commercial sprayer technologies, i.e. multi-fan heads, pneumatic, and electrostatic sprayer, were evaluated for their canopy deposition and drift in the 2016 and 2017 production seasons. Data were collected in Vitis vinifera ‘Chardonnay’ and ‘Riesling’ vineyards at two application timings, early season and mid-season, to determine sprayer deposition patterns in opposed and unopposed application spray row canopy and in-field aerial as well as ground drift. All sprayer technologies showed consistent in-canopy deposition and drift patterns at both application timings. Regardless of sprayer technology, the most deposition was in the upper canopy compared to the fruiting zone of the vines. Similarly, the most aerial and ground drift was in the row closest to the sprayed row, indicating that drift is relatively low with the three evaluated sprayer technologies.

Influence of Trap Color, Type, and Placement on Capture Efficacy for Protaetia brevitarsis (Coleoptera: Scarabaeidae)

In recent years, Protaetia brevitarsis Lewis has gradually become an important pest of several crops including grape (Vitis vinifera L.) and peach (Amygdalus persica L.) in Xinjiang, China. Toward improving trapping efficacy as part of a management program, various colors, types, and placement of traps and the use of an attractant were evaluated in field and laboratory studies. Laboratory color-choice tests and field tests indicated that P. brevitarsis adults preferred red. In trap placement tests, more adults were captured on traps placed 1 or 1.5 m above the ground and on top of the horizontal grape canopy. Before grape ripening, more adults were captured in traps placed in a 0.5-m border around the outside edge of the vineyard; during grape ripening, more were caught within the vineyard. Newly designed traps that were red, with a triangular baffle and a landing plate, were more efficient than traditional bucket-shaped traps. When P. brevitarsis adults were trapped and killed from June to July 2018, the population of P. brevitarsis adults in August to early September 2018 was significantly lower than in August to early September 2017, when adults had not been trapped and killed in the prior 2 mo.

An Empirical Assessment of Angular Dependency for RedEdge-M in Sloped Terrain Viticulture

For grape canopy pixels captured by an unmanned aerial vehicle (UAV) tilt-mounted RedEdge-M multispectral sensor in a sloped vineyard, an in situ Walthall model can be established with purely image-based methods. This was derived from RedEdge-M directional reflectance and a vineyard 3D surface model generated from the same imagery. The model was used to correct the angular effects in the reflectance images to form normalized difference vegetation index (NDVI) orthomosaics of different view angles. The results showed that the effect could be corrected to a certain scope, but not completely. There are three drawbacks that might restrict a successful angular model construction and correction: (1) the observable micro shadow variation on the canopy enabled by the high resolution; (2) the complexity of vine canopies that causes an inconsistency between reflectance and canopy geometry, including effects such as micro shadows and near-infrared (NIR) additive effects; and (3) the resolution limit of a 3D model to represent the accurate real-world optical geometry. The conclusion is that grape canopies might be too inhomogeneous for the tested method to perform the angular correction in high quality.

Juice Grape Canopy Structure and Cluster Availability Do Not Reduce Middle- and Late-Season Captures of Male Paralobesia viteana (Lepidoptera: Totricidae) in Sex Pheromone Traps.

Paralobesia viteana (Clemens) (Lepidoptera:Tortricidae), the grape berry moth, is a major economic pest of cultivated grapes in eastern North America. Although pheromone lures and traps are available for monitoring this pest, male moth captures in these traps decline as the infestation risk increases through the multiple generations that occur during a season. This makes it difficult to use traps to monitor this pest's population dynamics and complicates the timing of pest management activities. To test whether seasonal changes in the plant canopy affect captures of male grape berry moth, we manipulated grapevine fruit density or canopy structure in multiple growing seasons, and measured male captures under these conditions. Removal of either 50 or 100% of the fruit clusters from vineyard plots did not consistently affect captures in pheromone traps. In 2013, significantly more males were captured in traps in plots where clusters were not removed compared to captures in traps in plots where 50 or 100% of clusters were removed, but this effect was not seen in 2014 or 2015. In the first year of a separate experiment, there were no differences in male captures between unaltered canopies and those held open artificially. In subsequent years we detected significant differences in male captures for some sample periods, and there was a prevailing trend of arithmetically more male captures in unaltered than in open canopies. We conclude that fruit presence, fruit density and canopy fullness do not reduce male P. viteana captures late in the season, and that other factors are driving this pattern.

Berry anthocyanin content of Cabernet Sauvignon (Vitis vinifera L.) cultivated under rain-shelter systems with different coloured plastic films

ABSTRACTCovering vineyards with rain-shelters is an effective viticulture practice to protect grapes from adverse environments, and the rain-shelter can influence radiometric properties, canopy microclimate, and grape berry quality. We investigated the effect of rain-shelter cultivation covered with different coloured plastic films on canopy microclimate and anthocyanins in the skins of Cabernet Sauvignon grape berries through comparison with open-field cultivation (control) of two vintages (2013 and 2014) in northern China. The results show that the highest average temperature and lowest relative humidity were presented by the grape canopies in the open-field cultivation, followed by the colourless, blue, purple, yellow, and red film. Higher infrared radiation was recorded in control plants. The content of sugar in the berries under rain-shelter cultivation (except colourless film in 2013) was significantly higher than that of the control. The concentrations of most anthocyanins were significantly decreased under the yellow and colourless films in the two vintages. The red and purple films increased the concentration of 3ʹ,5ʹ-substituted, methoxylated, and acylated anthocyanins in the grapes in both vintages. The results suggest that the application of such films may be useful for the production of high-quality wine grapes in warm temperate climates with dry winter and hot summer regions.

Deployment and Performance of a Uav for Crop Spraying

Small, unmanned aircraft systems (UAS) provide an opportunity for pesticide spray application in which the applicator can be displaced from close proximity of the spray discharge and in which the spray application can be made with highly targeted spatial resolution, particularly in challenging geographic terrain. In this project, a commercially manufactured UAS-mounted spray system was deployed in high-value specialty crops in California. The UAS used in this project was a unmanned aerial vehicle (UAV) and an associated ground control station that provided a means for remote piloting of the aircraft. The aircraft was a petrol-powered helicopter (RMAX, Yamaha Motor Co. USA, Cypress, CA USA) originally developed for spraying of rice fields in Asia. In this test, the primary experimental areas for spray deposition and performance assessment included a 0.61 ha block of Cabernet Sauvignon wine grapes located at the University of California Oakville Field Station in Napa County, CA USA. The block consisted of 42 rows, each 61 m long with a row spacing of2.4 m. Depending on the spray method deployed, specifically, the swath width used and the flight pattern flown, the UAS spray application could achieve 2.0 to 4.5 ha/h work rates while applying volume rates of 14.0 to 39.0 L/ha. Spray deposition on the grape foliage increased with applied volume rate. In comparisons to ground-based sprays at 935 L/hr, deposition in the grape canopy from the UAS at 47 L/ha was similar.

USE OF VERY HIGH-RESOLUTION AIRBORNE IMAGES TO ANALYSE 3D CANOPY ARCHITECTURE OF A VINEYARD

Abstract. Differencing between green cover and grape canopy is a challenge for vigour status evaluation in viticulture. This paper presents the acquisition methodology of very high-resolution images (4 cm), using a Sensefly Swinglet CAM unmanned aerial vehicle (UAV) and their processing to construct a 3D digital surface model (DSM) for the creation of precise digital terrain models (DTM). The DTM was obtained using python processing libraries. The DTM was then subtracted to the DSM in order to obtain a differential digital model (DDM) of a vineyard. In the DDM, the vine pixels were then obtained by selecting all pixels with an elevation higher than 50 [cm] above the ground level. The results show that it was possible to separate pixels from the green cover and the vine rows. The DDM showed values between −0.1 and + 1.5 [m]. A manually delineation of polygons based on the RGB image belonging to the green cover and to the vine rows gave a highly significant differences with an average value of 1.23 [m] and 0.08 [m] for the vine and the ground respectively. The vine rows elevation is in good accordance with the topping height of the vines 1.35 [m] measured on the field. This mask could be used to analyse images of the same plot taken at different times. The extraction of only vine pixels will facilitate subsequent analyses, for example, a supervised classification of these pixels.

Remote Sensing of Soil Moisture in Vineyards Using Airborne and Ground-Based Thermal Inertia Data

Thermal remote sensing of soil moisture in vineyards is a challenge. The grass-covered soil, in addition to a standing grape canopy, create complex patterns of heating and cooling and increase the surface temperature variability between vine rows. In this study, we evaluate the strength of relationships between soil moisture, mechanical resistance and thermal inertia calculated from the drop of surface temperature during a clear sky night over a vineyard in the Niagara region. We utilized data from two sensors, an airborne thermal camera (height ≈ 500 m a.g.l.) and a handheld thermal gun (height ≈ 1 m a.g.l.), to explore the effects of different field of views and the high inter-row temperature variability. Spatial patterns of soil moisture correlated more with estimated thermal inertia than with surface temperature recorded at sunrise or sunset. Despite the coarse resolution of airborne thermal inertia images, it performed better than estimates from the handheld thermal gun. Between-row variation was further analyzed using a linear mixed-effects model. Despite the limited spatial variability of soil properties within a single vineyard, the magnitudes of the model coefficients for soil moisture and mechanical resistance are encouraging indicators of the utility of thermal inertia in vineyard management.

Quantifying the combined effects of climatic, crop and soil factors on surface resistance in a maize field

• The response of surface resistance to climatic, crop and soil factors was investigated. • A surface resistance model was construed based on the response pattern. • The surface resistance model was compared to the widely used Jarvis and KP models. • The surface resistance model combined with PM estimated sparse vegetation ET accurately. Land surface evapotranspiration (ET) is the central process in hydrological cycle. The accuracy in simulating ET is affected by the calculation of underlying surface resistance. However, the surface resistance is difficult to be measured and greatly affected by climatic, crop and soil factors. How to quantify the combined effects of these factors on surface resistance is still a challenge for hydrologists. Our study attempted to construct and validate a semi-empirical surface resistance model based on the analysis of the response pattern of surface resistance to climatic resistance, leaf area index (LAI) and soil moisture. The surface resistance was derived by the re-arranged Penman–Monteith (PM) equation and the measured maize ET using eddy covariance in 2007. Results indicate that the ratio of surface resistance to climatic resistance showed a logarithmic relationship with LAI, and an exponential function as soil moisture when LAI was below 2. But the ratio was nearly constant and not sensitive to variation in LAI and soil moisture when LAI exceeded 2. Based on the relationships, a surface resistance model was further constructed and compared to the widely used Katerji–Perrier and Jarvis models over the sparse maize and grape canopy. Our resistance model combined with the PM equation improved the accuracy in estimating daily maize ET by 11% in 2007 and 4% in 2008, and vineyard ET by 7% against the Katerji–Perrier model combined with PM method, while by 32% in 2007 and 104% in 2008, and vineyard ET by 5% against the Jarvis model combined with PM method. Thus our model significantly improved the performance in simulating sparse vegetation ET and can be used to estimate daily surface resistance under the partial canopy condition.

Spatial variability of leaf wetness duration in a 'Niagara Rosada' vineyard

Despite considerable efforts to develop accurate electronic sensors to measure leaf wetness duration (LWD), little attention has been given to studies about how is LWD variability in different positions of the crop canopy. In order to evaluate the influence of 'Niagara Rosada' (Vitis labrusca) grapevine structure on the spatial variability of LWD, the objective of this study was to determine the canopy position of the ‘Niagara RosadaÂ’ table grape with longer LWD and its correlation with measured standard LWD over turfgrass. LWD was measured in four different canopy positions of the vineyard (sensors deployed at 45º with the horizontal): at the top of the plants, with sensors facing southwest and northeast (Top-SW and Top-NE), and at the grape bunches height, with sensors facing southwest and northeast (Bottom-SW and Bottom-NE). No significant difference was observed between the top (1.6 m) and the bottom (1.0 m) of the canopy and also between the southwest and northeast face of the plants. The relationship between standard LWD over turfgrass and crop LWD in different positions of the grape canopy showed a define correlation, with R² ranging from 0.86 to 0.89 for all period, from 0.72 to 0.77 for days without rain, and from 0.89 to 0.91 for days with rain.

Comparing surface wetness inside and outside grape canopies for regionwide assessment of plant disease risk

Wetness duration measured by flat plate sensors inside and outside a grape canopy was recorded from DecemberMarch Sensors outside the canopy generally recorded longer wetness duration than sensors inside the canopy For days with rain short wetness durations detected by outside sensors were not detected by inside sensors because of sheltering by the canopy When wetness arose solely from dew duration inside was much shorter than outside for prolonged wet periods Wetness was used to calculate infection periods according to two botrytis bunch rot risk models Agreement between sensors was worse inside the canopy than outside although on occasions when rainfall exceeded 10 mm there was greater uniformity between sensors For regionwide disease risk monitoring wetness duration measured outside leaf canopies at standard meteorological sites would give a worstcase estimate of disease risk Regression equations are presented that allow estimation of inside wetness duration from outside wetness duration for rainy and nonrainy days

Assessing root death and root system dynamics in a study of grape canopy pruning

Defining root death in studies of root dynamics is problematic because cell death occurs gradually and the resulting effects on root function are not well understood. In this study, metabolic activity of grape roots of different ages was assessed by excised root respiration and tetrazolium chloride reduction. We investigated changes in metabolic activity and patterns of cell death occurring with root age and changes in root pigmentation. Tetrazolium chloride reduction of roots of different ages was strongly correlated to respiration (R2 = 0.786). As roots aged, respiration and tetrazolium chloride reduction declined similarly, with minimum metabolic activity reached at six weeks. Tetrazolium chloride reduction indicated that the onset of root browning corresponded to a 77% reduction in metabolic activity (P < 0.001). Anatomical examination of roots at each pigmentation stage showed that even though some cells in brown roots were still alive, these roots were functionally dead. The effect of using different definitions of root death in relation to root survivorship was determined in a study of ‘Concord’ grapes with two pruning treatments, using three criteria for root death: browning, blackening or shriveling, and disappearance. There was no effect of vine pruning on root life span when life span was defined as the time from first appearance to the onset of browning. However, if death was judged as the point when roots either became black or shriveled or disappeared, vine pruning decreased root life span by 34% and 40%, respectively (P < 0.001), and also increased the decay constant for root decomposition by about 45% (P < 0.001). We conclude that the discrepancy among determinations of root life span assessed with different definitions of death might be partly caused by the latter evaluations of root life span incorporating a portion of root decomposition in definitions of root death.

Remote Image and Leaf Reflectance Analysis to Evaluate the Impact of Environmental Stress on Grape Canopy Metabolism

Research suggests that blackleaf (a leaf disorder in grape, Vitis labrusca L.) is induced by high levels of ultra violet (UV) radiation and overall light intensity, resulting in color changes (purple-brown-black) for sun-exposed leaves of the outer canopy, and a corresponding >50% reduction in photosynthesis. Metabolic indicators (photosynthesis and leaf water potential), percent blackleaf expression, and full spectrum leaf reflectance were mapped within vineyards using global positioning system (GPS) and digital remotely-sensed images. Each image and data record was stored as an attribute associated with a specific vine location within a geographical information system (GIS). Spatial maps were created from the GIS coverages to graphically present the progression of blackleaf across vineyards throughout the season. Analysis included summary statistics such as minimum, maximum, and variation of green reflectance, within a vineyard by image capture date. Additionally, geostatistics were used to model the degree of similarity between blackleaf values as a function of their spatial location. Remote-image analysis indicated a decrease in percent greenness of about 45% between July and August, which was related to a decrease in photosynthesis and an increase in blackleaf symptom expression within the canopy. Examination of full spectral leaf reflectance indicated differences at specific wavelengths for grape leaves exposed to UV or water-deficit stress. This work suggests that remote-image and leaf spectral reflectance analysis may be a strong tool for monitoring changes in metabolism associated with plant stress.

Environmental fate of pesticides used in Australian viticulture III. Fate of dithianon from vine to wine

Pinot noir, bastardo, rkaziteli and semillon grapes on vines grown in the Barossa Valley of South Australia were treated with a commercial dithianon formulation. The grapes were harvested by hand eight days later, and made into wine. Grab samples of berries, grape juice and the young wine were analysed for fungicide residues. No dithianon was detected in control grape samples, grape juices or wines. Significant dithianon levels were detected on the skins of treated grape samples. Dithianon is stable on the surface of grapes under the ambient conditions prevalent under the grape canopy for at least two weeks. No dithianon was detected in grape juice, on grape skins after berry crushing, in the lees, or in the young wine. Dithianon is unstable in grape juice and wine. Dithianon half‐life (initial concentration = 1 μg/mL) in semillon grape juice = 2.8 h, semillon wine = 0.58 h, pinot noir grape juice = 4.6 h, and pinot‐noir wine = 0.29 h. Treatment with fining agents or heat does not significantly reduce the rate of degradation. These results suggest that spraying table grapes with dithianon two weeks before harvest would result in exposure to essentially the full dose of active ingredient sprayed, and increase the risk to human health through ingestion of this compound. However, any threat to human health from ingestion through grape juice or wine is limited since any contact with grape juice or wine leads to rapid decomposition of dithianon by some as yet undetermined process.

Structural analysis and flux associations of CO 2, H 2O, heat and ozone over cotton and grape canopies

Micrometeorological tower data, collected over grape and cotton canopies as part of the California ozone deposition experiment (CODE) during the summer of 1991, are used to examine the temporal association between fluxes, and the physical characteristics of the coherent structures which dominate transport for both stable nighttime and unstable daytime conditions. Flux was calculated using the eddy covariance technique and the dominant modes of flux transport determined by quadrant analysis. The mean flux densities for both the cotton and grape site showed the surface acting as a sink for CO 2 and ozone and a source of heat and H 2O during the day, as would be expected, while during the night it became a source for CO 2 and a sink for heat, but remained a sink for ozone and a source of H 2O. The flux association results indicated a single vegetated ozone sink for the grape site, but a vegetated as well as a non-vegetated sink for the cotton site. For both sites, structures simultaneously transporting significant flux contributions of CO 2, H 2O, heat and ozone dominate during unstable conditions, but differed during stable conditions, where unmixed single flux structures dominated over cotton but not over grape. Structure sizes were less than 10 m during nighttime conditions and ranged from 3 to 69 m during the day. The results of this study contribute empirical evidence about the relationship between ozone uptake and the physical and physiological state of vegetation, as well as the limitations placed on eddy scales in simulation models.

Four Grape Canopy Systems in Texas

I. Chennin Blanc 107-cm bilateral cordon spaced 3.6 × 2.4 m, 1119 vines/ha, 14 spurs with 32 buds/vine. Yields were 8.8 t·ha-1 in the third leaf; 9.7 in the fourth, and 12.8 the 5th year, 1990, at the Jane Terrell Vineyard, Navasota, Tex. II. Cabernet Sauvignon with a two-trunk 122 cm bilateral cordon spaced 3.3 × 1.2 m, 2445 vines/ha with 48 buds/vine. Yields were 9.7 t·ha-1 for 1994 through 1997 at the mechanically harvested Newson Vineyard, Plains, Tex. III. Le Noir with a 91-cm trunk and a two-cane canopy; spaced 3 × 2.1 m, 1536 vines/ha, with 14 buds/vine. Yields were 13.3 t·ha-1 in 1996 and 11.2 in 1997 at Messina Hoff Vineyard, Bryan, Tex. IV. Merlot/110R with a 45° slanting cordon, 30 cm at south to 152 cm at north, spaced 1.5 × 1.5 m, 4308 vines/ha with 10 spurs and 20 buds/vine. Yield of 10.8 t·ha-1 in the third leaf, 1997, at Wolf Vineyard, Valley View, Tex. Four very different canopy systems were successful; the ideal system is yet to be determined.