Agricultural Extension Service The University of Tennessee PB 1475 Introduction 3 Grapevine Propagation from Cuttings 1 Types of Grapes 3 Grapevine Propagation from Layering 2 Site Selection 4 Soils 4 Suggested Spacings for Grapevines 3 Propagation 4 Planting an Own-rooted Grapevine 4A Planting Time to plant 5 Planting a Grafted Grapevine 4B Purchasing vines 6 Vertical Trellis Design 5 Spacing 6 Preplant care 7 High-Head Bilateral Cordon Trellis 6A Planting 7 Low-Head Bilateral Cordon Trellis 6B Pruning and Training Terminology 8 Geneva Double Curtain (GDC) Trellis 7 Trellis design and construction 8 2-Wire Vertical Trellis 8 Training systems 11 Pruning at planting 11 End Post and Brace for a Single-Wire Trellis 9 Vertical trellis systems: Common Training Systems for Grapes 10 4-cane kniffin 11 Pruning and Training, First Year 11 umbrella kniffin 14 Hudson River umbrella 14 4-Cane Kniffin System 12 bilateral cordon 14 Vertical Trellis Systems, First Dormant Pruning 13 Horizontal trellis systems: Geneva double curtain 16 4-Cane Kniffin System, Mature Vine 14 Pruning bearing vines 16 Umbrella Kniffin System 15 Balanced pruning 16 Time to prune 18 Hudson River Umbrella System 16 Trunk renewal 19 Bilate Cordon System, First Dormant Pruning 17 Pruning neglected vines 19 Disposal of prunings 20 Spur Pruning Grapevines 18 Fertilizing and Liming 20 Geneva Double Curtain (GDC) Training 19 Vineyard Floor Management 21 Pest Control 23 New Wood Versus Old Wood on Grapevines 20 Estimating Yields in Vineyards 23 Cross Section of a Compound Bud of Concord 21 Harvesting 25 Storage 26 Trunk Renewal 22 Additional References 26 Vineyard Floor Management 23 David W. Lockwood, Professor Darren K. Robinson, Assistant Professor Plant and Soil Science

Grapes may be grown in all parts of Tennessee. However, not all types of grapes or varieties of grapes are adapted to all parts of the state. With proper attention to selection of the correct type and variety of grapes, site selection and reasonable cultural practices, grapes can be a viable crop for both commercial and hobby growers. The development of commercial wineries and the introduction of several seedless grape varieties adapted to Tennessee growing conditions have contributed to grape production becoming an increasingly important part of Tennessee’s agricultural economy.

French-American hybrid nay, and Cabernet Sauvignon tend Several different types of varieties are crosses between Eu- to be less winter-hardy and more grapes are grown in the United ropean varieties and certain wild subject to fungal diseases than ei- States. Each type has characteris- species found in America. Fruit ther American grapes or French- tics that may make it more or less from the “hybrids” is used prima- American hybrids. Expect lower desirable than others in terms of rily for wine. Varieties include yields and less consistent produc- adaptability and use of the fruit. Seyval, Vidal, Foch, DeChaunac, tion with viniferas than other American grapes used for Chambourcin and Chancellor. types of grapes. They should only fruiting are usually one of two Many of the hybrid varieties will be grown in the most desirable species; Vitis labrusca (i.e. Con- perform as well as several of the sites and with the best cultural cord, Niagara) or Vitis aestivalis American bunch varieties. practices. Due to the likely pres- (i.e. Norton, Delaware). American Muscadine grapes (Vitis ence of root phylloxera, V. vin- varieties tend to be more adapted rotundifolia) grow well in many ifera varieties should be grafted to Tennessee growing conditions parts of the Southeast. Unfortu- onto phylloxera-resistant than the other types. Fruit from nately, cold injury to cordons and rootstocks. While test plantings of these varieties is widely used for trunks can be a fairly common oc- viniferas are encouraged, exten- juice, wine, preserves and fresh currence in most parts of Tennes- sive plantings are not suggested consumption. see. Therefore, commercial mus- for Tennessee at this time. Several seedless grape variet- cadine grape production is not Many grape varieties, in addi- ies have been developed. They do suggested for most parts of the tion to those listed above, are also not yield as heavily as seeded state. Fruit from muscadine vines available. Refer to Extension PB American varieties. However, is used for juice, wines, process- 746, “Tree Fruit, Tree Nut and they do offer potential for fresh ing and fresh consumption. Small Fruit Cultivars for Tennes- fruit sales. Vitis vinifera (European see,” for more suggestions. grape) varieties, such as Chardon- poor, creating a delay in develop- While grapes may be grown Grapevines can be deep-rooted ing a productive vineyard. under a wide variety of conditions, in certain soils. Ideally, vines need Most grapevines, with the ex- certain factors may make one site a minimum of 24 to 36 inches of ception of V. vinifera varieties, are more desirable than another. rooting depth before encountering grown on their own roots. V. vin- Areas elevated above their im- an impervious layer, such as rock ifera varieties are especially sensi- mediate surroundings offer some or a hardpan. The deeper and more tive to root phylloxera, which is a protection from frosts and dis- extensive the root system, the more threat throughout the country. eases. Injury to buds or new capable the vine will be to with- Therefore, these vines are grafted growth due to frost becomes more stand stresses such as drought, low onto resistant rootstocks (Dia- likely the closer you get to the fertility and low soil temperatures. grams 4A and 4B, Own-rooted vs. basal part of a slope. Likewise, While water is essential for Grafted Vines). fogs keep foliage and fruits wet, growth and production, grapevines American bunch varieties and thus increasing the potential for will not tolerate excessive soil French-American hybrid varieties certain diseases. By establishing moisture, especially during the may be propagated by cuttings. the vineyard higher up the slope, growing season. Sites with poor Cuttings should be taken in early both frost and disease pressure internal and/or surface drainage to midwinter from healthy, well- may be lessened. The very top of a characteristics should either be matured canes. The ideal cuttings hill may not be the most desirable modified to solve the problem or are about 1/4 to 3/8 inch in diam- spot, however, as wind damage avoided. Irrigation is desirable on eter and three to four nodes in and winter freeze injury are apt to excessively droughty soils. length (Diagram 1). The bottom become more of a problem. Grapes do not require highly fertile cut should be made just below the Direction of slope may have soils. In fact, such soils are unde- basal bud. The top cut should be some impact on vineyard perfor- sirable, since growth may be ex- made about 1 inch above the mance. Vines on a north to north- cessive, causing shaded, poor- top bud. eastern slope tend to be less prone quality fruit and increased disease to winter damage and spring frost pressure. For soils with low to diameter injury than those on a slope with moderate fertility levels, a liming 1/4” - 3/8” some southern orientation. Vine- and fertilization program may be yards on an eastern-facing slope devised that will give a balance may have less disease pressure between vegetative growth and than on other slopes, since the fruiting. Knowledge of soil charac- morning sun dries off fruits and teristics before planting is valuable foliage earlier on the eastern slope, in determining the best vine spac- thereby lessening the chances for ing and trellis system to use. 9”-12” disease development. Grapevines should be planted where they will receive full sun. Grapevines may be success- Shade will cause plants to become fully propagated by several meth- “leggy.” These elongated, spindly ods. It may be possible to propa- shoots will produce fewer fruiting gate your own plants if existing sites with poorer quality fruit that vines are healthy and if proper pro- Diagram 1. Grapevine are more prone to disease prob- cedures are followed. If these crite- Propagation lems. ria are not met, rooting success and from Cuttings subsequent plant growth will be Cuttings should be grouped time, they may be dug, stored un- Strip off developing shoots on into bundles of uniform lengths der moist conditions at about 34 F. the long cane between the mother with the top ends together. Bundle until planting time or transplanted vine and the soil. Shoots arising each variety separately. Bundles directly from the nursery row to from nodes above the soil line on may be moistened, put in plastic the vineyard at the appropriate the tip of the long cane should be bags, sealed and held in refriger- time. retained. Do not allow the layered ated storage (keep from freezing) Layering is the surest way to plant to fruit for two years. or buried in a trench with the basal propagate all grape varieties. How- Do not separate the layered ends up and covered with several ever, it is seldom used except for vine from the mother vine until the inches of soil and/or mulch. The varieties that do not root readily diameter of the trunk of the new trench should be well-drained. If a from cuttings, such as with musca- vine is greater than that of the protective structure such as a dines and Cynthiana. Layering is wood leading to it from the mother greenhouse is available, cuttings also the preferred technique to fill vine. This would indicate the can be set immediately without the vacancies in established vineyards young vine has a functional root need for storage. where vines are growing on their system and no longer is dependent The area in which the cuttings own roots, since young vines re- on the mother vine. (Diagram 2). will be placed should be free of main attached to the mother vine Grafting, including budding, is weeds and worked 10 to 12 inches until well-established. a fairly technical procedure. The deep. Irrigation is highly desirable. To layer a grapevine, dig a specific type of graft to be used Once the danger of frost is hole 10 to 15 inches deep where will depend on the size of the vine past, cuttings may be set in the the new vine is desired. This loca- being topworked and the time of nursery. Place the cuttings about 6 tion must be close enough to the year in which it will be done. Ad- inches apart in the trench, with all mother vine so it can be reached ditional information on grapevine buds except the top one below soil by a long cane. Select a cane on propagation may be obtained at level. Backfill the trench and firm the mother vine and prune it to a your county Extension office. the soil around the cuttings. length about 3 feet greater than the Keep the nursery rows free of distance between the vine and the weeds throughout the growing sea- hole. Extend the long cane to the Time to plant son. Control of insects and dis- bottom of the hole, then bend it The ideal time to plant bare- eases is essential to maximize vertically upward so that at least root grapevines in Tennessee is in growth. Carefully monitor mois- two buds remain above the soil late winter to early spring (mid- ture levels and water when neces- once the hole is refilled. February to early April). Vines sary. Fertilization is not needed in most cases and is definitely not recommended in the early stages of growth, as fertilizer burn may occur to tender, new roots. If fertil- izer is used during the growing season, keep it several inches away from the base of the cuttings. Use about ounce of 10-10-10 fertilizer or its equivalent per linear foot of 3 - 4 buds nursery row. Do not fertilize after mid-July. Cuttings should be held in the Diagram 2. Grapevine Propagation from Layering nursery row until dormant. At that planted in fall or early winter may space rows 10 to 12 feet apart. Do suffer root injury or death in the Space grapevines about 8 feet not space rows less than 6 feet event of a prolonged cold period apart in the rows. This spacing apart, as mutual shading among shortly after planting. If planting may need to be increased to about rows may become a problem. later than early April, hot, dry con- 10 feet for vigorous varieties set on (Diagram 3. Suggested Spacings ditions may occur that could re- fertile soils, or reduced to 6 feet for for Grapevines). Table 1 shows the duce plant growth or even cause weak-growing varieties planted on number of vines needed per acre at plant death. less-fertile soils. For muscadines, a several in-row and between-row spacing of 16 to 20 feet apart in spacings. To calculate the number rows is suggested. The distance of vines needed per acre, multiply Since vineyard establishment between rows will depend on the the distance between vines in a can be fairly expensive, and since size of the equipment being used to row by the distance between rows a properly maintained vineyard maintain the vineyard, the lay of to find the square feet of space for will live and fruit for many years, the land (extra distance between each vine. Divide this number into it is very important to purchase rows may be needed on steeper 43,560 (the number of square feet healthy plants of the correct vari- slopes) and the type of trellis con- in an acre) to get the number of ety. Therefore, purchase plants structed to support the vines. Com- vines per acre. from reputable nurseries. As long mercial grape growers generally as the vines are properly cared for in the nursery and during shipping, it is not necessary to purchase 8 - 10 ft. between vines in a row them from local nurseries. Vigor- ous, one-year-old plants are best. Once plants are received, take care to prevent roots from drying out, freezing or overheating. The number of plants needed to supply fruit will vary consider- 10 - 12 ft. between rows ably, depending on the use of the fruit and the number of people who American Bunch, French-American Hybrids, will be consuming it. Calculate the V. vinifera and Seedless Grapes number of vines needed based on the assumption that each mature plant will yield about 15 pounds of 16 - 20 ft. between vines in a row fruit (25 to 35 pounds for a mature muscadine vine) and that about 15 to 20 pounds of fruit are required to give about one gallon of juice. Realize that these figures are only rough estimates and that several factors may influence them. 10 - 12 ft. between rows

Muscadines

Diagram 3. Suggested Spacings for Grapevines the nursery. Dig holes deep enough Table 1. Number of Vines per Acre and wide enough to accommodate the root system without having to Distance between rows bend roots to fit (Diagram 4A. 8 feet 10 feet 12 feet Planting an Own-Rooted Grape- vine). Grafted grapevines should Distance 6 feet 907 726 605 be set with the graft union just between above the soil line (Diagram 4B). vines in 8 feet 680 544 453 Set the vine in the hole, spread out a row the root system and work soil in 10 feet 544 435 363 around the roots to eliminate air pockets. Once the soil has covered 16 feet 340 272 226 the root system, tamp it down to further assure good root/soil con- 20 feet 272 217 181 tact. If the soil is dry, pour water in v i n e s / a c r e the hole before completely filling the hole. Fill the hole with soil to Example: 8 feet between vines in a row x 10 feet between rows = 80 square feet per vine. Divide 80 into 43,560 to get 544.5 vines per acre the same level or slightly higher (round off to 544 vines.) than the surrounding ground. If a depression in the soil is left at planting, it should be filled before Inspect vines upon receipt to Inspect the root system before going into the first dormant season. be sure the roots have not dried planting. Prune off broken, dead, Freezing and thawing of water in out, frozen or overheated. Healthy diseased or insect-infested roots. direct contact with the trunk could roots should feel firm, not spongy Do not prune the root system any damage it. or hard and brittle when squeezed. more than is absolutely necessary. DO NOT add soil amend- You should be able to bend the Grapevines propagated from ments such as peat moss, sawdust roots some without breaking cuttings or layering should be or manure to the soil being used to them. Cutting through the exterior planted as deep as they were set in backfill the hole. Such a practice of a root should reveal white tis- sue. If the interior of the root is tan to brown, the roots have been damaged and plant survival is apt to be poor. scion Store vines in a cool area. Take care to prevent the roots from drying out, freezing or be- coming too hot. If properly stored, graft union vines may be kept in the shipping bundle for several weeks before rootstock planting. Soak vine roots in water for a couple of hours prior to planting. Take care to prevent the roots Diagram 4A. Planting an Diagram 4B. Planting a from drying out during planting. Own-Rooted Grapevine Grafted Grapevine creates a “flower-pot” effect, Terminology Training — development of which discourages root growth into Arms — major branches of the framework of the vine on the the surrounding soil. The more re- the trunk on which canes or spurs trellis. Training impacts exposure stricted the root system of the are borne. of fruit and foliage to light, as well grapevine, the more susceptible the Cane — a mature, woody as ease of management. vine will be to drought, flooding or shoot after leaf drop. Trunk — the semi-permanent, improper fertility. Do not put fer- Cordon — extension of a above-ground, vertically-oriented tilizer in the hole because plant trunk, usually oriented horizontally stem of a vine. roots may be injured or killed by along a wire. Fully developed cor- direct contact with high amounts dons can bear spurs and canes. of certain fertilizer materials. Cordons may extend in one or two directions from the trunk. They are The trellis of a vineyard should retained for several years. be strong, long-lasting and require Pruning — removal of parts low maintenance. Its purpose is to Pruning and training are two of a plant. It is done to regulate support the foliage and fruit of separate practices that play very crop size and fruit quality. Pruning vines, thus allowing good light in- important roles in the development also is used to determine the qual- terception and ease of manage- and maintenance of grapevines. ity, quantity and location of veg- ment. Trellis construction repre- They influence light distribution etative growth. The two basic sents a major investment in both throughout the canopy, which types of pruning for grapes are 1) time and money. greatly affects yields, fruit quality cane renewal (cane replacement), Two types of trellises are sug- and pest problems. Ease of man- in which canes that fruited the pre- gested for use in Tennessee vine- agement of the vines and the crop vious year are removed and some yards. The vertical trellis uses two will be impacted by pruning and canes that grew the previous year wires. The lower wire is situated at training practices. Support wires are selected for fruiting in the cur- 3 feet aboveground to enhance on the trellis should be set at a rent year, and 2) spur pruning, good air circulation under the height that will make pruning, where short canes that fruited the vines, and the top wire is at about cluster thinning and harvest more previous year are removed and re- 6 feet aboveground (Diagram 5). convenient. placed with spurs on the cordon as The vertical trellis is used for the Early in the life of the vine- a site for fruiting and shoot growth four-cane Kniffin system, the um- yard, pruning and training are used the current year. Pruning should be brella Kniffin system and the together to build a vine of the de- done every year of the vine’s life. Hudson River umbrella system. sired size and shape. Once the vine Shoot — green growth from a The bilateral cordon system, a has filled its allotted space on the bud on a cane, spur, cordon, arm or variation of the vertical trellis, uses trellis, annual pruning is used to trunk. A shoot always bears leaves a single wire to support the cor- renew fruiting wood, to promote and tendrils and may also bear dons and the crop. This wire may uniform light distribution through- fruit. In the fall, a shoot matures be 6 feet aboveground for a high- out the canopy and to keep the and drops its leaves. It is then head cordon system where new vine from overgrowing neighbor- called a cane. shoots grow down, or 3 feet in ing vines. Pruning and training are Spur — cane pruned to a few height for a low-head cordon sys- parts of an integrated vineyard nodes (five or less). A renewal tem where new shoots grow up. management system in which each spur has one or two buds to pro- Movable catch wires may be used practice has an influence on the duce canes at a particular location to position shoots in either the success of all other cultural prac- on an arm or cordon. A fruiting downward (Diagram 6A) or up- tices and on the overall crop. spur is chosen to produce fruiting ward (Diagram 6B) direction. A shoots. 3 ft. Diagram 5. Vertical Trellis Design

3 ft.

2 ft. 3 - 4 ft. 16 - 24 ft.

Cordons Before pruning After pruning

Diagram 6A. Catch wire High-Head Bilateral Cordon System

Downward cane growth form spur buds

Upright growing shoots

Catch wire

Cordons Spurs

Diagram 6B. Low-Head Bilateral Cordon System Before pruning After pruning horizontal trellis is used for the Geneva double curtain (GDC) sys- 4 ft tem (Diagram 7). This system uses three wires. One wire, attached to the posts about 3 feet above 5 - 6 ft ground, is used for trunk support. Two parallel, horizontal wires at- tached to the ends of 4-foot long 2 - 3 ft cross arms secured to posts at 6 feet aboveground hold the cordons or canes. Descriptions of posts, anchors and wire needed for trellises reflect 16 - 20 ft the needs in commercial vine- yards. Limited plantings using Diagram 7. only a few vines per row may not Geneva Double-Curtain need such a heavily constructed (GDC) Trellis trellis. Posts should be long-lasting. Wood posts should be treated for in-ground use and should last up to 20 years. Line posts should be at least 8 feet long. The posts should be set Diagram 8. 2 - Wire at least 2 feet in the ground and Vertical 3 ft extend aboveground 6 feet or Trellis more. Line posts should have a top diameter of 3 inches or more. They 3 ft should not be spaced more than 24 feet apart. Depending on vine 2 ft spacing, two or three vines may be 3 ft Posts 16 - 24 ft apart between line posts. Line posts are used to maintain the correct wire height in rows (Diagram 8). End posts are used to maintain wire height. All wire tightening Diagram 9. and tensioning is done from the End Post and end posts, so they need to be Brace for a strong. End posts should be at least Single-Wire Trellis 5 - 6 ft 10 feet long to allow them to be set 450 300 3 to 4 feet in the ground and still have at least 6 feet of post aboveground (Diagram 8). These posts should have a minimum top 3 - 4 ft 3 - 4 ft diameter of 4 inches. Larger end posts are suggested for Geneva good light penetration throughout constructed by planting time, set a double curtain trellises. The stabil- the canopy of the vines. Cornell stake beside the vine and loosely ity of an end post can be increased University recommends tensioning secure the trunk to it as it grows by setting or driving it so the the wire to 250 to 300 pounds. (Diagram 11). If more than one aboveground part of the post is shoot develops, pinch the tip out of angled away from the vineyard all of them except the one selected at about 30 degrees from the verti- Many different types of train- to be the trunk. Trunk development cal and braced or anchored ing systems are used in grapes. is the prime consideration in train- (Diagram 9 ). The following listing outlines con- ing a new vine. For some types of Many types of braces or an- ditions that might favor the use of grapes that tend to be more suscep- chors can be used. A screw-in an- a particular training system (Dia- tible to cold injury, having two or chor 4 to 6 inches in diameter gram 10): more trunks may be advisable. On works well. The anchor should be 1. 4-Cane Kniffin — use on low- vines grown from rooted cuttings, set 4 feet away from the base of vigor varieties so canes on the the second trunk should originate the post and screwed in at a 45- upper wire do not shade those on at or below the ground line. For degree angle toward the end post the lower wire. grafted vines, the second trunk and aligned with the row. The an- 2. Umbrella Kniffin — suggested should originate above the graft chor should go in the ground at for high-vigor varieties such as union. Ideally, the trunks should be least 4 feet. Concord, Niagara and Fredonia. of different ages to lessen the The wire suggested to support 3. Hudson River Umbrella — use chance of cold injury damaging all the weight of the canes or cordons, on vines having medium to high the trunks. Trunks should be re- foliage and the crop is a number vigor. newed about every 15 years. In 11, crimped, high-tensile (210,000 4. Bilateral Cordon — use on vines cases of cold injury, mechanical p.s.i.), steel wire with a class III of low to medium vigor. damage or other problems, trunks galvanizing. Lower wires used for 5. Geneva Double Curtain — sug- may need to be renewed sooner. trunk support or for securing the gested for vines high in vigor. ends of canes on some systems can be of a lower tensile strength. Uncrimped number 11 or 12 galva- Regardless of the trellis system 4-cane Kniffin system nized fence wire works well. or training system being used, The 4-cane Kniffin system Wire may be secured to line pruning and training of newly set (Diagram 12) uses fruiting canes 1 posts by stapling it with a 1 to 1 /4 - vines is the same. New vines on both the upper and lower wires. inch fence staple in the top or in should be cut back to a single Wires should be 3 feet and 6 feet the side 2 to 5 inches below the top shoot. That shoot should be cut aboveground to facilitate good air, or by drilling a hole in the line post back to two buds prior to bud light and spray penetration 2 to 3 inches below the top and break to maximize shoot growth throughout the canopy. With vig- threading the wire through it. If the first growing season. If the trel- orous vines, the lower tier of canes using staples, be sure to not drive lis has been constructed at the time can be heavily shaded, resulting in them in tight, as this could weaken of planting, loosely tie a string low production and poor-quality the wire and also prevent tighten- from the vine to the lower trellis fruit. Where this problem arises, it ing and retensioning the wire. wire and secure the new shoot to is possible to convert to the um- Taut wires are necessary to the string. This is important in de- brella kniffin system. If possible, minimize sagging of cordons or veloping a straight trunk, which orient rows on the 4-cane kniffin canes, to reduce development of promotes a stronger, more produc- system north and south for the best crooked trunks and to promote tive vine. If the trellis has not been performance. 4-Cane Kniffin System Bilateral Cordon System

Umbrella Kniffin System Hudson River Umbrella System

Diagram 10. Common Training Systems for Grapes

Geneva Double Curtain (GDC) System

Diagram 11. Pruning and Training First Year

Loosely tie 1 new shoot to a vertical stake

Prune to 1 shoot with 2 buds Cane

Renewal spur 3 ft

8 - 10 ft Trunk 3 ft

2 ft 3 ft 8 - 10 ft

Diagram 12. 4-Cane Kniffin System

Pruning mature vines (Diagram upper and lower wires. Prune 14) involves the following steps: these canes back to two buds. 1. Remove at the trunk all canes They are called “renewal spurs.” that bore fruit the previous year From them, shoots will grow. (old wood). Some of these shoots will be 2. Select canes that grew the selected using the above criteria previous year (new wood) on for fruit production in two years. each side of the trunk near both 4. Shorten the four canes retained the upper and lower wires and for fruit production to eight buds train them to the wires. These each for weaker varieties and 10 Diagram 13. canes will bear the next fruit to 12 buds each for stronger- Vertical Trellis Systems First crop. growing varieties. This Dormant Pruning 3. Select four more canes from the technique is an approximation previous year. Keep one on each of the balanced pruning concept During the first dormant prun- side of the trunk for both the suggested for commercial ing (one year after planting), head the trunk about 4 inches above the upper trellis wire (Diagram 13). Before pruning After pruning Lateral branching will result from the heading cut and canes that will Fruiting cane, 8-12 buds fruit the following year can be se- lected. In some cases, sufficient Renewal spur trunk growth may occur to allow heading the trunk above the wire during the growing season. Elimi- nate all flower clusters, as the pri- mary goal at this stage is to de- Old wood velop the vine and fruiting will re- Trunk New wood duce growth. During the next dor- mant pruning, canes can be trained to the upper and lower trellis wires on each side of the trunk. Diagram 14. 4-Cane Kniffin System, Mature Vine vineyards. If desired, the Shoots balanced pruning concept, described later in this publication, may be used for more precisely determining the optimum bud number. Renewal Arm spur

The umbrella Kniffin system Tie shoots to the lower wire (Diagram 15) is a modification of the 4-cane Kniffin system. It is a Trunk head-training system suggested for vigorous varieties where more of the fruiting area is exposed to sunlight than would be the case in Diagram 15. Umbrella Kniffin the 4-cane Kniffin system. Cordons At planting, vines are handled as previously discussed. The trunk should be headed about 6 to 12 inches below the top wire. Two to six canes having eight to 15 buds each arising from the head (or heads) of each vine are selected. Each cane is bent sharply over the top wire and is extended down to Tie shoots to the lower wire the lower wire, where it is tied. Approximately the same number of renewal spurs as canes are left. The renewal spurs should be left near the head of the vines. Arms at Diagram 16. Hudson River Umbrella the head of a mature umbrella- Kniffin are usually kept at least 1 shoots that grow from buds on the support wire on downward foot or more in length. spurs are directed vertically growing grapes should be downward and tied to the lower positioned at 6 feet aboveground. wire. At pruning, head shoots (now The lower wire of the vertical called canes) back to three to four trellis would serve as a trunk The Hudson River umbrella bud spurs. Remove some spurs support wire and a catch wire for system (Diagram 16) is a directly at the cordon to stimulate new shoot growth (Diagram 6A). modification of the Umbrella development of new growth With the upright growing grapes, Kniffin system where the arms directly off the cordons. the wire that will support the extend along the top wire halfway cordon should be about 3 feet to the next vine. These arms, now aboveground. Wires above this called cordons, will live and bear Some types of grapes have a level may be used as “catch wires” fruiting spurs for several years. downward growth habit, while to support new shoot growth Spurs arise along cordons and other types grow up. The cordon (Diagram 6B). Catch wires are used to position shoots. They aid Before pruning After pruning in maintaining a narrow canopy to Space spures 6 to 8 inches apart facilitate good light penetration throughout the canopy and to keep Leave 2 to 4 buds per spur the drive areas between rows free of obstructions. The developing trunk(s) should be headed to promote lateral branching about 4 to 6 Remove older spurs inches below the trellis wire that whenever possible will support the cordon (Diagram 17). A single shoot should be trained to this trellis wire in each direction from the trunk to within Diagram 18. Spur Pruning Grapevines Head trunk 4 - 6 inches below the cordon wire

Diagram 17. Bilateral Cordon System First Dormant Pruning about 12 inches of the shoot on the 8 - 10 ft adjacent vine. This shoot will be 4 ft retained for several years and will be referred to as a cordon in 4 - 5 ft subsequent years. Cordons should 5 - 6 ft be renewed every six to eight years. Annual pruning of mature vines trained to this system Diagram 19. Geneva Double Curtain (GDC) Training (Diagram 18) involves elimination of old spurs and canes and selection of new shoots to be spurs in the lower 180 degrees of adjacent spurs. Shoots to be used pruned back to spurs arising the cordon (diagram 6A). Space for spurs should be pruned back to directly from the cordons. For spurs 6 to 8 inches apart on the two to four buds in length, upright-growing grapes, develop cordons. Do not develop a spur at depending on grape variety. In the spurs on the upper 180 degrees the bend of a cordon between the subsequent years, if new shoots of the cordon (Diagram 6B). For trunk and the wire, as it will tend grow directly off the cordons, downward-growing grapes, select to be overly vigorous and shade develop some of them into spurs and prune off adjacent older spurs be done on the wires. Annual cane Once an area on a cane or spur at the cordon. renewal pruning involves has fruited, it will never fruit in The number of spurs, the removing those that bore the that same region again. Instead, distance between spurs and the previous year’s crop, selecting future yields will be borne on number of buds left on each spur at canes arising on the trunk near the lateral shoots and extension pruning depends on the type, the wire and training one of them in growth. Therefore, regardless of variety and the vigor of the grape. each direction on the wire for the the type of pruning conducted, an next crop. These canes will need to important goal is to remove old be adjusted for bud number. Select wood that has already fruited and two more canes arising near the to select canes or spurs arising Geneva Double Curtain (GDC) point where the trunk intersects the directly off the trunk, renewal When properly maintained, the wire and prune them back to two spurs or cordons for the next crop. Geneva Double Curtain system buds. These “renewal spurs” will The further clusters develop away (Diagram 19) exposes more fruit be the source of new shoots, some from the main framework of the and foliage to sunlight than many of which will be selected for fruit vine, the poorer the size and other systems. It covers a greater production the following year. If quality of the clusters will be and percentage of land area with vines are to be spur-pruned, the thicker the canopy will be, thus foliage and fruit than other training cordons will be developed on the limiting light, air and spray systems. GDC offers a way to wires in the same manner as penetration throughout the canopy. double the cordon length per vine, described for the bilateral cordon New canes to be selected for while maintaining good sunlight system. Select 10 to 12 equally fruiting have smooth bark that is exposure throughout the canopy, a spaced, downward-growing, short often bronze-colored, with real benefit for vigorous varieties. shoots and prune them back to prominent buds. Older wood will Two trunks may be developed per spurs from which fruit and shoots have gray, shaggy bark and no vine, with each trunk being trained will develop. As with the bilateral buds (Diagram 20). to opposite cordon wires, or a cordon system, spurs that bore fruit single trunk can be split below the should be removed and new shoots low wire by heading the trunk 6 to arising directly from cordons The objective of pruning is to 12 inches below the wire and then should be selected for pruning obtain consistently large crops of training shoots arising on the trunk back to spurs each year. high-quality fruit. Perhaps the key to opposite wires. These wires word in this statement is should be 4 feet apart to allow for “consistently.” How much pruning sunlight penetration between the Regardless of the training should be done varies with grape canes or cordons trained on them system and trellis used, the steps variety, soil type, fertilizer throughout the growing season. used in pruning mature grapevines applications, water and several When each trunk reaches the are similar: other factors. The balanced appropriate wire, it should be 1. With the exception of trunks and pruning concept was developed by headed to encourage lateral shoot possibly cordons, remove all researchers at Cornell University development. One shoot should be wood that is older than one year. to aid in attaining this objective. trained in each direction. For less 2. Select canes or spurs for next With balanced pruning, a vigorous varieties, train vines to year’s crop and for renewal grapevine is pruned back, leaving alternate sides and develop only spurs. Remove all others. the maximum number of buds two cordons per vine. 3. Adjust the length of remaining suggested for that variety Cane renewal (cane canes or spurs to the desired depending on its growth the replacement) or spur pruning may number of buds. previous summer. The prunings New Wood (Canes) that grew the previous year are weighed and this figure is then used to refine the number of buds to be left. For example, according Prominent buds, smooth bark (often bronze color) to Table 2, Concord should have a maximum of 60 buds on vines set 8 feet apart. For the first pound of Old Wood cane prunings, 30 buds should be left. For each additional pound of prunings, 10 more buds should be Gray, shaggy bark and no visible buds left, up to a maximum of 60 buds. While weighing prunings sounds Diagram 20. New Wood versus Old Wood on Grapevines like a tedious undertaking, it won’t

Table 2 Number of buds to retain for fruiting

Grape variety First pound of Each additional pound Maximum number of buds cane prunings of cane prunings per vine at 8 ft. spacing American Bunch- Concord 30 plus 10 60 Fredonia 40 plus 10 70

Niagara 25 plus 10 60 Delaware “ ” “ Catawba “ ” “

French-American hybrids - Small-clustered varieties such as Foch and Leon Millot 20 plus 10 50

Medium-clustered varieties such as Aurore, Cascade and Chelois 10 plus 10 40

Large-clustered varieties such as Seyval, DeChaunac and Chancellor 20 plus 10 45

Vinifera varieties (prune after growth 20 plus 20 60 has begun) take long before you can estimate buds to determine how close to the pruning weights and forego Pruning in fall may interfere desired bud number to prune. weighing on a regular basis. Be with the vine’s ability to harden off Frosts or freezes may destroy a sure to weigh only the prunings properly, thus increasing the portion of the primary buds, from the previous year’s growth. potential for winter injury. The leaving varieties that are not highly Overcropping, which may also optimum time to prune grapevines fruitful on secondary buds with the be regarded as underpruning, is in late winter to early spring. potential for a light crop. With results in small clusters and small When done at this time, vines will varieties like Seyval, which tend to berries. High levels of shade will “bleed.” Bleeding is not be quite fruitful on secondary result in poorer-quality fruit and detrimental to vines. Pruning in buds, it is possible to prune to the increased pest pressures due to late winter to early spring enables final desired bud number. For poor light, air and spray you to assess the extent of cold varieties that are not highly fruitful penetration. Vines weakened by injury and prune it out. on secondary buds, it may be the excessive crop become more Delayed pruning involves advisable to leave 50 percent more susceptible to cold injury and may pruning after growth has started. buds than needed, in case cold not initiate enough fruit buds for Bud break begins on the ends of injury reduces the number of the next year’s crop. canes first and progresses toward surviving buds after pruning. If Overpruning (undercropping) the trunk. With both cane this is done and no bud kill occurs leaves too few buds to give a good replacement and spur pruning, a following pruning, vines should crop. Bull canes (very vigorous portion of the cane will need to be either be pruned again or cluster canes) are more susceptible to cold removed to adjust bud number. By thinning must be used to adjust injury than canes growing at more waiting to prune until 4 to 5 inches fruit load to the proper level. modest rates. The high vigor of new growth are present on the Grapes have compound buds causes heavy shading, with an ends of canes, bud break in the made up of primary, secondary and inevitable decrease in fruit quality area where fruiting is desired can tertiary buds. The primary bud will and increase in pest pressure. Also, be delayed by 10 to 14 days. This break first and will have the since the distance between buds may be of merit in avoiding injury greatest yield potential. It is also increases with increasing cane due to a late frost. the bud most likely to be killed by vigor, it may be impossible to Double pruning may be used spring frosts. If this should occur, retain the desired number of buds when time constraints in spring the secondary bud will break and while keeping canes within their won’t allow delayed pruning. It give rise to new shoots and allotted space. involves pruning out excess canes blooms. Many grape varieties will Weak vines should not be prior to bud break. Those to be produce a substantial crop from allowed to carry a heavy crop, as retained for fruiting are either left secondary buds. Most American fruiting can be an exhaustive alone or not pruned as far back as varieties are not highly fruitful on process. It is advisable to retain at the ideal bud count would require. secondary buds; however, several, least 15 to 18 nodes on a weak Then, after the remaining canes but not all, French-American vine and then remove all clusters have attained 4 to 5 inches of new hybrid varieties are. Cayuga White as soon as they begin to develop, terminal growth, they should be is an example of a hybrid variety as opposed to pruning vines back pruned to the correct length. Bud that is not highly fruitful on to just a few nodes. break in the desired area will be secondary buds. If the secondary delayed as a result. buds are also killed, the tertiary If pruning is done before bud buds may break and give rise to break, it is important to know how new vegetative growth. No grape fruitful the variety is on secondary varieties are fruitful on tertiary buds (Diagram 21). wood, it may be better to destroy the old vine and plant a new, 4 healthy vine. If the variety is unknown or no longer available, it may be possible to propagate new vines by taking cuttings or layering 3 1 2 5 the old vine. Information of this procedure is given in the section on “Propagation.” Several characteristics are common with neglected vines. Fruit-bearing wood develops further away from the trunk. Diagram 21. Cross section of compound bud of Concord grape Neglected vines may have a fair 1. Primary bud 2. Secondary bud 3. Tertiary bud 4. Lateral shoot 5. Leaf scar amount of dead wood. They will frequently have more than one trunk. Several steps should be taken when pruning such a vine. Damage to trunks by freezing, First, remove any large, dead equipment contact, insects, In some instances, vines that canes or cordons. This will make it diseases, etc. may lessen vine have been neglected for a period of easier to identify those that may be productivity over time. Trunk years can be restored to a retained. renewal will offset this problem. It productive condition. However, if Second, inspect the trunks. If is advisable to renew trunks on the period of neglect has been too possible, cut off one or more of the vines at least every 12 to 15 years, long or if the vine has a lot of trunks at ground level and remove and perhaps more frequently where dead, diseased or insect-infested them from the trellis. This will problems have occurred. If a sucker arises at the base of a vine, do not prune it off. Instead, secure it to the trellis wires to keep it growing straight. Use the same training method as was employed renewal trunk in new plantings. Once the trunk has reached an acceptable height, cut off the old trunk during the Leave one new cane. Secure new cane and head it at the trellis wire. dormant pruning and develop new canes from the replacement trunk (Diagram 22). For vines with multiple trunks, stagger the time that trunks are renewed to reduce fluctuations in cropping. Also, since different age trunks may differ in their susceptibility to cold injury, the Retain older trunks, allow new cane to Remove the damaged trunk, replacing it effect of this problem may be less develop into a third trunk. with the new one. Prune to one cane on the devastating. new trunk. Spur prune the following year. Diagram 22. Trunk Renewal make decisions concerning the rest potential from diseased or insect- years. Low rates of fertilization of the vine easier. Also, cutting a infested wood. If prunings are may result in inadequate growth to live trunk off at ground level may removed, do not stockpile them support the plant and the increase chances of getting a near the vineyard, as they will developing crop. High rates will sucker to grow from below ground serve as a source of pest problems promote excessive growth and too level. This sucker may be that will spread back into the much shade in the fruiting zone of developed into a replacement vineyard. Burning prunings is the vine. The result will be poor- trunk. probably the best way to deal with quality fruit and high disease If healthy canes exist close to them, since it will eliminate insect pressure. Nitrogen application the trunk, cut off the cordons on and disease carryover problems. should be made in late winter to the trellis wires and train the canes early spring prior to the to the wires. Prune them back to resumption of growth. the desired length. If no new Grapevines will grow and fruit Magnesium deficiency may healthy canes exist, select the best satisfactorily over a pH range of occur in some vineyards. It appears cordon on each side of the trunk 5.5 to 7.0. Since the vines will be as an interveinal chlorosis for each trellis wire. Remove all in place for many years and since (yellowing of the leaf tissue other cordons. Spur-prune the it is difficult to modify the pH of between the leaf veins) beginning cordons that are being retained. the subsoil after planting, soil first on the basal leaves and Develop canes closest to the trunk testing prior to planting is highly progressing upward toward the to replace cordons during the next recommended. In a preplant younger leaves. The appearance of dormant pruning. situation, take a sample in the magnesium deficiency close to Several years may be needed upper 8 inches of soil and a second harvest is not a cause for alarm. to renovate a vine that has been sample at the 8- to 16-inch depth. However, if the problem shows up neglected. The overall objectives If lime or nutrients are needed in earlier in the growing season, steps should be to eliminate dead, the subsoil area, incorporate them should be taken to correct the diseased or insect-infested wood, at the recommended rates prior to problem. If the soil pH is below to gradually renew trunks and planting. 5.5, an application of dolomitic cordons and to develop the fruiting For established vineyards, limestone may correct the wood close to the trunk. nitrogen may be the only element problem. Where the soil pH is Once the vine has been needing application on an annual above 5.5, consider spraying renovated, annual pruning is basis, especially if attention was magnesium sulfate (epsom salts) at essential to keep it productive. paid to the preplant soil test the rate of 16 lb. per 100 gallons of recommendations. Apply water using 200 gallons of spray ammonium nitrate at the rate of 0.3 per acre in each of two post-bloom Prunings can either be lb. or the equivalent in nitrogen sprays. chopped on the vineyard floor or from another source per vine in an Information and supplies removed form the planting. A flail area extending from 4 to 6 feet out regarding soil testing are available mower can chop prunings into from the trunk. If another fertilizer at your county Extension office. very small pieces and place them is to be used, be sure to make the Assistance in interpreting results of in contact with the soil, where they necessary rate adjustment based the soil test, if needed, may be present very few problems with the upon the actual nitrogen content of obtained there as well. carryover of insects or diseases. the fertilizer. The amount of Rotary mowers do not chop nitrogen may be adjusted prunings fine enough to reduce the depending on plant performance reinfection or reinfestation and cropping history in preceding of vegetation under the vines plus Tennessee, and prairie voles, a mowed sod strip between the found from the Cumberland rows and around the perimeter of Plateau west, live and feed on the vineyard (Diagram 23.) the top of the ground in the Each aspect of this mulch layer. Thus, maintaining Weed control is an essential management system provides the vegetation-free strip step in optimizing quality grape certain benefits that optimizes the eliminates protective cover, production and ensuring the long- long-term health of the vineyard. discouraging voles from term health of both the commercial Under the vines, maintaining the inhabiting the area. Pine voles, and home vineyard. Grass weeds area devoid of vegetation provides which are found throughout the (like crabgrass and bermudagrass) the following benefits: state, work underground, and and broadleaf weeds (like 1. Elimination of competition from therefore are not as easily dandelion) compete heavily with weeds for moisture and discouraged. Firm, bare soil the vines for growth requirements nutrients, thereby achieving under vines will lessen their (such as water and nutrients). greater growth rates, especially activity. Controlling weeds under the vines in new vines. 3. Minimize frost events. Firm, directs the resources to the vines as 2. Minimize vole damage by moist, bare soil absorbs more well as facilitating good air preventing the buildup of a heat during the day than any drainage and eliminating sites for mulch layer under the vines. other ground management pest problems to develop. Weed Grape vines can be damaged or system. Heat is reradiated from control in the vineyard is best killed by voles feeding on the the soil at night over a longer achieved by adopting a vineyard roots and stem. Meadow voles, time than with other floor floor management program, found in the northeastern part of management systems, thus including a continuous strip devoid

Diagram 23. Vineyard Floor Management Program • 10 to 12 feet between rows • 4-foot wide strip under vines free of vegetation • 6 to 8-foot wide sod strip between rows

6 - 8 ft.

10 - 12 ft.

4 ft. providing some additional weeds may serve as an alternate rotovators may cause damage to protection from frost events. In host to pests. Thus, grass sod is the vines. Cultivating clay soils addition, the absence of preferred. Ideally, the grass sod when they are too wet may result vegetation allows for improved should be non-competitive, in formation of a shallow, cold air drainage, providing requiring minimal mowing. The compacted layer (or plow pan) that additional frost protection. fine fescues (red and hard fescue) will limit root growth and restrict 4. Minimize insect and diseases by are the least competitive, requiring water movement to the roots. In lessening alternate host sites. less mowing compared to tall addition, cultivation is also time- Certain weeds provide an fescue. They also go dormant consuming and expensive. alternate host site for pests of during the heat of the summer. Herbicides provide the easiest, grapes so their absence could However, seed for these grasses is least expensive and most effective result in a lessening of pressure more expensive than tall fescue method of controlling annual and from certain pests in the and slow to establish (fall is the perennial weeds. Herbicides are vineyard. The potential for optimum establishment time), safe when used properly, including problems with grape root borer thereby leaving vineyard floors being applied at the right amounts can also be lessened by susceptible to erosion during and the right times. Always read removing many of the egg- establishment. Tall fescue is the and follow the use directions for laying sites that weeds under dominant grass cover in most the herbicide product on the vines provide. In addition, the Tennessee vineyards. product label. Choice of herbicide presence of weeds decreases air Tall fescue seed is relatively and application timing may be movement, creating humidity inexpensive, readily available and dependent on the size of the pockets favorable for the quick to establish (if it is not vineyard being maintained. development of certain already established in the site). Many herbicide selections are diseases. Tall fescue supports equipment available for commercial vine- On sloping land, rows should traffic well. However, tall fescue is yards. The best option may be a be planted across slopes rather competitive for water and nutrients combination of herbicides. No one than up and down slopes. and requires more frequent herbicide, applied one time at the Maintaining a sod strip between mowing during the growing recommended rates, will give year- rows provides the following season. If not controlled, it will long control. Thus, for season-long benefits: provide favorable habitat for voles. control, the best approach is two 1. Serves as a diffusion and This vineyard floor applications per year, using a deceleration strip for runoff management program can be combination of a non-selective water, thereby minimizing soil achieved by following a few easy herbicide (to control existing erosion. steps. Keep the sod mowed short weeds) plus preemergence or 2. Supports equipment movement, between rows and around the residual herbicides (to slow the re- especially in wet conditions. perimeter of the vineyard. Within emergence of weeds). The ideal 3. Minimizes frost potential when the row, maintain a 4-foot wide program includes an application in closely mowed, as drainage of strip (2 feet each side of the vine) early winter (November - cold air is less restricted. under the trellis free of vegetation. December) followed by a second 4. Minimizes vole habitat when Weeds (broadleaves and grasses) application of a different herbicide closely mowed. can be controlled by mechanical combination (to limit development Between rows, a grass sod is means or with herbicides. Shallow of herbicide-resistant weeds) probably the most desirable type of cultivation under the vines can be applied in early summer prior to ground cover, since certain used for control of annual weeds. extensive vine growth that may broadleaf ground covers and/or In cherty soils, grape hoes or interfere with with uniform application. For specific herbicide lessen the potential for frost injury Insecticides that may be effective options, contact your county and disease development. Factors against them have a relatively long Agricultural Extension office or favoring good air movement waiting period following consult University of Tennessee throughout the vineyard and application. Therefore, they cannot Agricultural Extension Service sunlight penetration throughout the be used shortly before harvest. publication PB1197, “Commercial canopy of the vines, such as high Removal of damaged fruit from Small Fruit Spray Schedules”. trellises and good pruning the vineyard before these pests This publication is revised practices, are invaluable for become a problem helps to reduce annually as herbicide products and reducing pest pressures and the intensity of the problem. directions for use change often. increasing fruit quality. Proper Harvested fruit should not be left In summary, vineyard floor fertilization practices to avoid setting in the vineyard, as bees and management is more than just weak vines or excessive growth wasps will be attracted to it. weed control. It is a vital part of an rates will aid in avoiding pest Elimination of nests prior to fruit integrated vineyard management problems. Vineyard sanitation, ripening may reduce activity in the program that aids in optimizing the including raking leaves, vineyard. However, location and production of quality grapes and elimination of mummified fruit destruction of the nests may be ensuring the long-term health of and removal of prunings will very difficult. either the home or commercial lessen pest pressures the following vineyard. growing season. Birds have become a major pest problem in many home and Having a fairly accurate Grapevines are vulnerable to commercial vineyards. Results estimate of yield prior to harvest attack from many pests. For most using aluminum pie pans enables growers to make types of grapes, a spray program is suspended in the vineyard and marketing arrangements for their necessary to produce fruit of plastic snakes on the vines, as well crop. It helps winery managers to acceptable quality and to maintain as several other practices, have know whether they will have a vine health. Two University of been erratic. Netting the vines is sufficient supply of fruit from their Tennessee Agricultural Extension the only sure way to keep birds regular growers or if they will need Service publications, PB1622, away. Nets should be put on before to investigate other sources of “Disease and Insect Control in bird pressure gets heavy. The net grapes for the upcoming crush. Home Fruit Plantings,” and should completely enclose the Early crop estimates can be used PB1197, “Commercial Small vines and either be tied under the by growers to determine if vines Fruit Spray Schedules,” offer vines or anchored to the ground to are being overcropped or timely information concerning pest prevent birds from getting under it. undercropped. If estimates are control in grapes and other fruit If possible, suspend the netting developed early, cluster thinning crops. These publications are above the vines, possibly by may be used to lessen the stress of available without charge at your extending another wire overcropping. county Extension office. When horizontally above the vines. This Yields will vary from year to using pesticides, exercise caution will keep the vines from growing year due to environmental factors and always follow label directions. through the netting. With care, and cultural practices. Therefore, Many cultural practices will netting can last for several years. crop estimates should be influence pest problems in Yellow jackets, bees and developed annually. The accuracy vineyards. If possible, select a site wasps do not reduce yields very of the estimates will be determined that is more elevated than the much. However, they do cause by the numbers used in making the immediate surroundings. This will problems during harvest. necessary calculations. Since weather conditions, pest pressures accurate determination of the The number of clusters on a and other factors will influence the average number of clusters per given area will vary from year to development of the crop following vine at the time the estimate is year depending on: the time that estimates are made, being made. • number of vines (vine loss over expect some differences between Factors influencing cluster time) the estimates and the actual yield. weight include: • number of nodes per vine Using accurate, precise • flowers per cluster (dormant pruning severity) information wherever possible in • berries per flower (percent fruit • number of shoots per node developing the estimates will set) (varies with variety, vine vigor increase the reliability of the crop • seeds per berry and the amount of shoot thinning estimates. • weight of fruit per seed used Developing accurate crop Variations in cluster weight • clusters per shoot (affected by estimates involves a thorough are influenced by the percent of variety, degree of bud injury, knowledge of the vineyard and flowers that set. Cloudy, rainy growing conditions for the vine growing conditions plus an weather during or immediately during the previous growing accumulation of information from following bloom, poor vine season. Shoots growing in heavy previous years. Crop estimates are nutrition and foliar damage from shade are more likely to have based on good records of average pests all will result in reduced nodes with less fruitful shoots the cluster weights at harvest, an cluster weights. following year. accurate count of the current living vines in an acre or block, and an

Use the formula below to estimate yield: Estimated Yield (pounds)/vine = (# of clusters/vine) x (average cluster weight) To get the yield estimate for several vines, simply multiply the estimated yield per vine by the number of vines. Commercial growers will want to modify the formula as shown below to get an estimate of tons per acre: Estimated Yield (tons/acre) = (# bearing vines/acre) x (clusters/vine) x (average cluster weight in pounds) divided by 2000. Clusters/vine may either be counted or calculated by multiplying the number of shoots per vine by the number of clusters per shoot. The number of bearing vines per acre may be calculated using the following formula:

(in-row spacing x between row spacing) Bearing vines/acre = ------missingvines in the acre 43,560 (square feet in an acre) or use the following chart if the vine spacings in your vineyard are listed: distance between vines distance between rows vines/acre 6 feet 10 feet 726 12 feet 605 8 feet 10 feet 545 12 feet 454 10 feet 10 feet 436 12 feet 363

Be sure to subtract the number of missing vines in the acre to give a more precise yield estimate. The number of clusters per weighed, select the vines, count vine may be calculated by the number of clusters on the vine, Grapes will not increase in multiplying the number of shoots harvest the fruit and weigh it, color or sugar level after harvest, per vine by the number of being sure to subtract the weight of so it is essential to allow them to clusters per shoot. The reliability the container. Then calculate the attain the desired level of maturity of the average cluster per vine average weight per cluster for that prior to harvest. Berry color should count increases as more vines are vine. not be used as an indicator of included in the count. Factors between sampling time maturity, since the color change Crop estimates can be made and harvest (i.e. amount of rainfall, can occur well in advance of any time after all the flower pest pressure, bird damage, deer ripening. clusters are exposed on a damage, etc.), are not constant As grapes ripen, the sugar developing shoot. However, from year to year. Therefore, using level of the berries will increase, waiting until after fruit set enables averages calculated from just one juice pH will increase and total you to calculate percent berry set, year’s crop can be misleading. acidity will decrease. The seeds giving a more accurate count. Estimates of yield are just that will turn from green to brown and Vines to be used in making — estimates. Hopefully, the will separate easily from the pulp. cluster counts should be selected estimate you arrive at will be The stem of the cluster will turn throughout the planting. The more within 10 to 15 percent of the brownish and become slightly vines that are counted, the more actual yield. The following tips wrinkled. accurate the count will be. How will help to increase the accuracy The best time to harvest will many vines to count will depend of the estimates: depend on the intended use for the on the size of the vineyard and the 1. Accumulate average cluster grapes. For jelly, grapes should be uniformity of the vines. For a one- weight data over a period of picked somewhat early to get a to two-acre vineyard with vines of years instead of just one year. light, clear jelly that will be free of a uniform age, size and training Actual cluster weights from crystals. Table grapes are picked system, only 10 to 15 vines may each harvest should be figured when seeds have turned brown and need to be sampled. In a larger into the average. flavor is at its peak and before vineyard where the vines may not 2. Develop cluster weights from clusters begin to shatter (berries be uniform, separate the vineyard your own vineyard. Do not rely start to drop). Wine grapes should into several uniform blocks and on those from other areas. be harvested when sugar levels, make counts from each block. 3. Sample the entire vine to get the juice pH and total acidity have Average cluster weight average cluster weight for that reached desired levels. These should be determined at harvest vine. levels may vary depending on the each year. This number should 4. Divide non-uniform blocks into type of wine to be made. then be included in an average for smaller, uniform sub-blocks and Uneven ripening of entire all the years in which cluster sample each of them separately. clusters or of berries in clusters weights have been recorded. 5. Sample each variety separately. may be a problem some years. Determine the average cluster 6. The same person should develop Weather stresses such as frosts or weight for each variety and each crop estimates each year to freezes may damage some primary block for all the years over which further reduce variation. buds (Diagram 21). In many data has been obtained. The more varieties, secondary bud break will years involved in developing the occur after clusters from primary average, the more accurate the buds have already started to average will be. Instead of develop. When clusters from the randomly selecting clusters to be primary buds are ready to be harvested, clusters from the secondary buds will still be green. These immature clusters should not be placed in containers with PB 746 Tree Fruit, Tree Nut and Small Fruit Cultivar Recommendations the ripe fruit, as they will reduce for Tennessee the quality of the juice. Uneven ripening within the PB1622 Disease and Insect Control in Home Fruit Plantings clusters of Concord grape is a varietal trait that becomes more PB1197 Commercial Fruit Spray Schedules noticeable in hot weather. The variety Sunbelt is being suggested Factsheet SP307N Selecting Quality Grapes for planting in areas where uneven ripening in Concord has been a Factsheet SP277J Black Rot of Grapes problem. Fruit should be harvested by clipping or cutting the stem of the fruit cluster. Pulling the cluster from the vines may cause grapes to fall from the cluster (shatter). Once harvested, fruit should not be allowed to get hot. Put it in the shade or in a cooler.

Most grape varieties grown in Eastern states cannot be stored for very long periods of time. As a rule, red varieties store longer than blue-black or white varieties. The ideal conditions for grape storage include temperatures of 30 to 33F and relative humidity of 85 to 90 percent. Refrigerators generally run about 40F and at low humidity levels. While this temperature is close to ideal, moisture loss from the fruit will be excessive if the fruit is not sealed in plastic bags.

PB1475-4M-03/01 E12-5215-00-005-01

The Agricultural Extension Service offers its programs to all eligible persons regardless of race, religion, color, national origin, sex, age, disability or veteran status and is an Equal Opportunity Employer. COOPERATIVE EXTENSION WORK IN AGRICULTURE AND HOME ECONOMICS. The University of Tennessee Institute of Agriculture, U.S. Department of Agriculture and county governments cooperating in furtherance of Acts of May 8 and June 30, 1914. Agricultural Extension Service, Charles L. Norman, Dean