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Vineyard Mechanization for Juice and Wine Production for Missouri and Mid-America

INTRODUCTION

The availability of skilled labor in most viticultural areas has become a very real problem. Not only has labor become scarce, but increasingly expensive and too often litigious. Doing the tedious work by machine seemed to be the answer; mechanical pruning, for instance, can reduce follow-up labor cost by as much as 50% (Table 1). There was a need throughout the viticultural world for an improved vineyard apparatus system and method for partial or complete vineyard mechanization. A system was needed that would eliminate the need for expensive hand operations without any substantial loss of yield while maintaining or improving vineyard consistency and fruit quality. Some of the new mechanical pruning systems developed and evaluated at the University of Arkansas when combined with mechanical fruit thinning can eliminate the need for follow-up pruning.

The author has conducted research work at the University of Arkansas for more than 32 years that has resulted in mechanized concepts and systems that will allow for complete mechanization of mature grape vineyards. Vineyard operations that have been previously mechanized include fruit thinning, leaf removal summer pruning and harvesting. Mr. Tommy Oldridge, a grape grower and inventor from Lowell, AR, has commercially built and tested machinery for the past 25 years that improved on most of the existing equipment. Through a cooperative effort between the author and Oldridge, the Morris-Oldridge Plan for mechanizing vineyards was developed and includes over 40 different machines and attachments that have been constructed and evaluated for the mechanization of 12 different trellising systems. These systems are part of a pending patent application which is the property of the University of Arkansas.

Although mechanical harvesters, mechanical shoot positioners and mechanical pruning devices have been used for some time, until now, there has not been commercially effective machines and apparatus for complete mechanization for many of the major trellising systems used for wine and juice grape cultivars. However, systems now have been packaged to handle all of these major production operations. These new systems provide for mechanization of both upright and drooping growth habit grape cultivars, and are versatile enough to be used with a multitude of trellis types or training systems. Of equal importance is the fact that these systems maintain fruit quality and are cost effective.

TABLE 1. Hands vs. Mechanical Pruning Grapes – Hudson River Umbrella and Geneva Double Curtain. James Merritt, grower, Chatauqua-Erie grape area, NY.

All amounts are measured in Hours per acre

PRUNING SYSTEM Equipment Operator Hand Pruning Total Labor
Single Top Wire Cordon
No shoot positioning, Hand pruned 17.6 17.6
Shoot positioned, Hand pruned 11.7 11.7
No Shoot positioning, Machine pruned, Hand follow-up 2.1 8.3 10.4
Shoot positioning, Machine pruned, Hand follow-up 2.2 4.5 6.7
Geneva Double Curtain
Shoot positioned, Hand pruned 10.5 10.5
Shoot positioned, Machine purned, Hand follow-up 3.3 5.4 8.7

Source: Vineyard and Winery Management, April 1979.

SYSTEM DEVELOPMENTS

New equipment has been developed, modified and evaluated for the mechanization of each viticultural operation requiring hand labor. As listed in Table 2, the Morris -Oldridge plan that mechanizes the major grape growing systems currently used in the United States and in other major grape producing countries. These systems involve mechanization of viticultural operations such as shoot thinning, canopy management, fruit thinning, leaf removal, summer pruning, harvesting and dormant pruning for established vineyards. Four of the systems shown have immediate application for viticulture in Missouri, mid-America and throughout the eastern United States. The following systems have been selected for presentation at this Missouri conference. System I deals with Vitis labruscana and other grapes with a drooping growth habit that are trained on a single curtain trellis system. A mechanical pruner has been developed that is very effective on these grapes. Mechanical pruning should start after leaf fall and may continue into late March. This machine has been previously patented by Mr. Oldridge. The first attempt to adjust the crop may begin in April when a mechanical shoot thinner can be used to remove excessive shoots when they are 2 to 3 inches long. Also at this time, mechanical touch-up pruning of long canes may be carried out if excessive fruit buds were left during dormant pruning.

TABLE 2. Twelve Mechanized Systems of the Morris-Oldridge Plan for Vineyard Mechanization

I. Vitis labruscana (and other grapes with drooping growth habits) on single curtain trellis

II. Vitis labruscana and other grapes with drooping growth habits) on GDC trellis and GDC-like canopy systems

III. Minimal pruned Vitis labruscana (and other grapes with drooping growth habits) on single curtain trellis systems

IV. Minimal pruned Vitis labruscana (and other grapes with drooping growth habits) on the GDC trellis systems

V. Vitis vinifera and French American hybrids produced on high wire single curtain

VI. Vitis vinifera and French American hybrids produced on GDC and other divided canopy trellises

VII. Minimal pruned Vitis vinifera and French American hybrids trained to a high wire curtain trellising system

VIII. Minimal pruned Vitis vinifera and French American hybrids on GDC trellis systems

IX. Vitis vinifera and French American hybrids produced on standard California T-trellis

X. Vitis vinifera and French American hybrids produced on standard vertical moveable catch wires

XI. Vitis vinifera and French American hybrids produced on Lyre or “U” and other divided canopy trellises

XII. Vitis vinifera and French American hybrids produced on Smart-Dyson ballerina (and similar) trellising systems

The shoots need to be positioned when the plants are in about 10% bloom, usually in May. A mechanical shoot positioner selected for this system has worked effectively when used one or two times. Then approximately 25 to 30 days after bloom, excess fruit may be removed with a mechanical shoot thinner. At maturity, an approved mechanical harvester for single curtain, drooping growth grapevines is used. We usually recommend a commercially available harvester with quad or bow rods.

System II deals with Vitis labruscana and other grapes with drooping growth habits trained on the Geneva Double Curtain (GDC) and GDC-like trellis systems. A mechanical pruner has been developed and patented by Mr. Oldridge that can be used to prune starting after leaf fall and going through the vines’ dormant period. Two of these pruning units can be mounted under an over-the-row harvester to prune both sides of the GDC in one pass. Also, a tractor-mounted model is available that prunes one side of the GDC and requires two passes on each row. At 10% bloom, the shoots need to be positioned. Also, a mechanical shoot positioner for this system has been patented. Mechanical shoot positioning and first fruit removal is carried out in May. Mechanical units have been developed which will remove excess fruit after berry set and shatter. At the end of June, approximately 25 to 30 days post bloom, final adjustment of fruit load to balance vineyard conditions by fruit removal is performed. Mechanical units for this operation are a part of the Morris-Oldridge System.

In July, the centers on these double curtain trellises need to be separated or broken. Mechanical units adequately perform this operation. At full maturity, the grapes are harvested with an approved harvester that can be equipped with quad rods or bow rods to assist in removing difficult-to-harvest fruit and allow for excellent fruit removal and minimal damage to foliage. This allows the vines to maintain maximum foliage that is capable of carrying out needed photosynthesis and storage of carbohydrates in the vines until frost and/or leaf drop.

System V describes the vineyard mechanization activities of Vitis vinifera and French-American hybrids trained on a high wire single curtain. Two mechanical pruners are recommended which will prune these vines starting after leaf fall and extending into the vines’ dormant period. One of these pruners has a cutter bar modification which is used above the cordon. New mechanized shoot thinners are available and are used in April when shoots are 4 to 5 inches, to adjust the fruit load early, if needed. One of these thinners has a patent pending and is extremely effective in carrying out this operation. Approximately 25 to 30 days post bloom, excess fruit can be removed by a choice of several machines which are part of the Morris-Oldridge system. One of the most effective machines also has a pending patent application. At this time, excessive leaves should be removed from the fruiting zones to expose 50 to 80% of the fruit to sunlight. The amount of fruit exposure will depend on the production region, vine vigor, vine size and other factors. The Morris-Oldridge system has machines for this purpose. This operation will improve fruit quality and aid in disease control through increasing light and air flow in the fruiting zone. Leaf removal is usually only recommended for reducing rot problems in susceptible cultivars and under high vigor conditions that prevent the fruit from being exposed to sunlight.

System X offers mechanization activities for Vitis vinifera and French-American hybrids produced on standard vertical moveable catch wires. A mechanical pruner has been built that prunes all the canes on this system to the desired node number. A new shoot thinner has been designed to thin shoots, if needed, when shoots are 4 to 5 inches in length. Approximately 25-30 days post bloom, excess fruit may be removed with one of two machines. To determine the amount of fruit load to retain on this system, as well as all previously mentioned systems, it is critical to know if it is possible to maintain optimum soil moisture, to optimize fertilization, to control pests and to optimize other critical production factors. Also, in regions with short growing seasons, the number of days after harvest and before frost become a consideration for determining fruit load. Externally, heavy fruit loads will delay the development of soluble solids and optimum fruit quality.

One of these machines is used to remove excessive basal leaves in fruiting zone approximately 25-30 days post bloom. This exposes the fruit to 50 to 80% of the sunlight. Another one of these units can be used for summertime pruning. At harvest use an approved commercial harvester, equipped with Quad-rods or bow-rods to remove difficult-to-harvest fruit. Select a harvesting system that provides excellent fruit removal but does minimal damage to foliage. With all systems, the harvester should allow for vines to maintain maximum foliage that is capable of carrying out needed photosynthesis and storage of carbohydrates in the vines until frost and/or leaf drop.

RESEARCH ON MECHANIZED PRUNING AND FRUIT REMOVAL

The foundation work on mechanized pruning was done by the author on a 22 year old ‘Concord’ grape vineyard at the Arkansas Agricultural Experiment Station at the University of Arkansas in Fayetteville. The vines were trained either to a Single curtain or a Geneva double curtain trellising system and were either hand pruned or mechanically pruned for 6 consecutive years. All vines were manually shoot positioned vertically toward the vineyard floor immediately after bloom and 2 more times on approximately 3 week intervals. Hand pruned vines had been balance pruned to a 30+10 severity (30 nodes retained for the first pound of dormant prunings and 10 additional nodes left for each additional pound of prunings removed), using 5 node canes. The mechanically pruned vines were either left untouched or followed by hand pruning to the 60 or 90 best nodes per vine (see Table 3).

All treatments were harvested on the same date. Fruit yields were recorded and approximately 5.5 pounds of fruit from each plot was collected for juice preparation. Juice was prepared by standard juice procedures and used to determine sensory quality. Retaining 90 or more nodes (allowing a heavy crop of grapes) following mechanical pruning on both training systems for 6 consecutive years resulted in reduced yields, low per node fruitfulness and juice of unacceptable objective quality. Marginal sensory acceptability occurred with 90 nodes retained and juice was unacceptable for no touch-up treatments (uncontrolled crop) regardless of training system. After the 6-year period, the lowest yields were obtained from vines that had been overcropped based on vine size and vigor. Limiting the number of nodes to 60 (controlling i.e. reducing, the amount of crop) following mechanical pruning maintained vine size and produced fruit yields and fruit quality comparable to vines balance pruned by hand to a 30+10 schedule.

It is the opinion of the author that fruit or crop adjustment would have prevented the quality and yield problems that occurred on the 6th and final year of this study. Of course, this crop adjustment could now be accomplished mechanically. The amount of fruit that should be removed has been reported by Dr Robert Pool of the NY Agricultural Experiment Station, Geneva. According to his method, berry development can be plotted against degree day accumulation. This curve shows that berries reach about 50% of their final size when about 1100 Fahrenheit degree days (50% oF base) have accumulated. By harvesting a predetermined number of vines at this time, the grower can estimate his crop and determine the desired crop and the amount to remove to reach that desired amount. Growers must know their vineyard well and do sufficient trials to ensure they get a representative sample of the vineyard. Also, careful attention must be given to variation within a vineyard (for examples: weak areas or areas with poor fruit set).

The Morris-Oldridge systems provide for methods and apparatus that will mechanically touch-up prune or shoot thin after pruning to simulate the fruit crop adjustment heretofore accomplished by hand. This mechanization has the added advantage of not only saving time and money, but final pruning need not be done so early that a late spring frost would reduce the crop by nature to far below vineyard’s production potential.

SUMMARY

Although complete vineyard mechanization systems and methods provide the viticulturist with an arsenal of tools, careful use and intelligent implementation of the desired results from each of these tools must be understood for the systems to be successful. Adoption of these new completely mechanized systems will mean a more reliable, more stable, and more economical production of premium quality fruit that will be competitive for the local, regional, national and global markets. The success of the Morris-Oldridge system has been the attention paid to eliminating all of the limiting factors that impact or influence the mechanization of a given trellising system while maintaining or in some cases improving fruit quality.

table3

Source: Morris and Cawthon. 1981. Am. J. Enol. Vitic. 32(4):280-82.

  1. Balanced pruned vines by hand, leaving 30 nodes for 1st # of dormant prunings and 10 nodes for each subsequent #.
  2. Treatment consisted of dormant pruning with a mechanical pruner and going back by hand to select the best 60 nodes on each vine.
  3. Treatment consisted of dormant pruning with a mechanical pruner and going back by hand to select the best 90 nodes on each vine.
  4. Machine pruned with no touch-up pruning or fruit thinning.
    * Under both GDC and SC trellis and training, the number one treatment consists of balance pruning vines to a 30+10
    z Means within columns followed by the same letter or letters are not significantly different at the 5% level, by Duncan’s multiple-range test.

Justin R. Morris, Distinguished Professor, University of Arkansas, 272 Young Avenue, Fayetteville, AR 72704. This paper was presented at the Midwest Regional Grape and Wine Conference. Lake-of-the-Ozarks, MO. Jan. 1998.