Extension Bulletin E-2774 • New • January 2002 Growing Table Grapes in a Temperate Climate Thomas J. Zabadal Department of Horticulture Graphics by Diane Dings Illustrations by Laurel Breyen MICHIGAN STATE UNIVERSITY EXTENSION Acknowledgments his publication results from more than a quarter century of experience with growing table grapes in the temperate climates of New York and T Michigan. Many growers in New York and Michigan were involved in experiments, trials, demonstrations and commercial table grape production on their farms. Dr. Bruce Reisch, Dr. Jim Moore, Elmer Swenson and Dr. Helen Fisher provided table grape plant material to be planted at the Southwest Michigan Research and Extension Center (SWMREC). Dr. Stan Howell, Dr. Dave Miller and Dr. Charles Edson made the first plantings of table grapes at SWMREC. Many SWMREC staff members — including Jim Ertman, Gaylord Brunke, Fred Froehlich, Tom Dittmer and Cassie Meier — have contributed to the management of table grapes planted at SWMREC. Thanks to Diane Dings and Laurel Breyen for contributing computer graphics and illustrations, respec- tively. Those contributing helpful comments on the manuscript include Jeanne VanNewenhizen, Wayne Baker, Joe Herman, Jordan Tatter, Al Lange, Dr. Jim Flore, Dr. Garth Cahoon, Dr. Stan Howell, Dr. Don Ramsdell, Dr. Ron Perry and Dr. Nick Dookozlian. An anonymous donor provided significant funding to defray the cost of publishing this manuscript. The Michigan Agricultural Experiment Station has funded many table grape projects that have contributed information in this publication. Thanks to MSU ANR Communications staff members Alicia Burnell, Leslie Johnson and Ken Fettig for editorial, graphic design and print production coordination. Diane Dings deserves special recognition for guiding the manuscript through numerous stages. Her dedication made this publication possible. Products are mentioned in this publication for informational purposes only, and such mention does not constitute endorsement by Michigan State University or imply discrimination against unmentioned products. Individuals should check current product registrations of all materials before purchase and use. 2 Table of Contents Introduction . 4 Vineyard Fertilization . 22 Insect and Disease Control . 22 Section I – The Structure of a Grapevine. 4 Strategies for a Pesticide Spray Program. 23 Shoots, Laterals, Trunks, Arms and Cordons . 4 Controlling Animal Depredation Nodes, Internodes, Fruiting Canes in Table Grapes . 24 and Fruiting Spurs . 6 Renewal Zone, Renewal Spurs Section IV – Special Practices to and Vine Space . 6 Produce Quality Table Grapes . 26 Suckers and Trunk Renewals . 7 Crop Adjustment . 27 Flower Cluster Thinning . 29 Section II – Getting Started . 9 Cluster Thinning . 30 Selecting, Designing and Preparing Berry Thinning . 31 a Vineyard Site . 9 Gibberellic Acid Sprays . 32 Selecting Grape Varieties to Plant . 10 Girdling . 32 Planting and Care of Young Vines. 11 Shoot Positioning . 35 Brushing . 36 Section III – Cultural Practices Shoot Topping . 37 For Managing Mature Grapevines . 13 Grapevine Training Systems for Section V – Harvest, Storage and Table Grape Production. 13 Marketing of Table Grapes . 38 Modified Munson Training . 13 Harvesting Table Grapes . 38 Modified 4-Arm Kniffin . 15 Storing Table Grapes . 38 Hudson River Umbrella . 15 Marketing Table Grapes . 39 Fan Training . 16 Arbor Training. 16 Appendix A – Available Publications . 40 Pruning Vines for Table Grape Production . 18 Pruning Severity . 19 Appendix B – Sources of Materials Selecting Fruiting Canes . 20 for Table Grape Production . 42 Steps in Pruning . 20 Spring Vineyard Chores. 22 References. 43 3 Introduction able grapes have become a very popular fruit grape production. These may include frost-free grow- in the United States. Annual per capita con- ing seasons of 165 days or less, winter minimum tem- sumption of table grapes in the United States peratures of -5ºF or lower, and growing season heat T accumulations of 3,000 growing degree-days or less has quadrupled over the past quarter century. It now exceeds 7 pounds per person, and grapes rank fourth (base 50ºF). Breeding programs have developed table after bananas, apples and oranges. Improved storage grape varieties well suited to temperate climates. With technology and extensive winter importation now the proper varieties and good management, it is possi- make table grapes available year round. ble to grow flavorful, high quality table grapes. This publication guides growers to that goal and comple- Though the major U.S. table grape production regions ments several other publications in this series: are in warm climates such as the San Joaquin Valley Vineyard Establishment (Zabadal, 1997; Zabadal and of California, many areas with temperate climates Andresen, 1997), Table Grape Varieties for Michigan have potential for exciting and profitable production of (Zabadal et al., 1997) and Pest Control in Small flavorful table grapes. Temperate climates are those Vineyards (Zabadal, 1999). Sources of these publica- that may have a warm growing season but have other tions are listed in Appendix A. temperature-related characteristics that challenge Section I – The Structure of a Grapevine hether you are a backyard viticulturist with trunk divides into branches, these branches are called no grape growing experience or a veteran arms. Arms are rough-barked portions of the vine grape grower, all efforts to grow table grapes other than the trunk(s). Sometimes a trunk is bent so W a horizontal arm runs along a trellis wire. This hori- must begin with an understanding of the aboveground structure of a grapevine. zontal arm is then called a cordon (Fig. 1f). New vine growth begins each year with primary shoots, which are the elongating green tissues with leaves. Primary Shoots, Laterals, Trunks, shoots often develop side branches, which are called Arms and Cordons lateral shoots. As a vine matures in the latter part of the growing season, shoots become woody from their The structure of a grapevine is really quite simple. base outward. After the leaves fall from the vine, these Trunks and arms are the rough-barked, semi-perma- smooth, tan or brown woody vine parts are called nent woody parts of the vine. A trunk is easy to iden- canes. Lateral shoots that become woody are called tify because it originates at or near the ground like the lateral canes or simply laterals (Fig. 1f). As the trunks on other woody plants (Fig. 1a). There can be shoots are maturing into woody canes in the latter one, two or several trunks on a grapevine. When a part of the growing season, the canes from the previ- 4 Section 1 — The Structure of a Grapevine Figure 1 a See Fig. 1b b Double trunks This cane will on new probably be grapevine girdled by the twine and should not be used. This cane kept because it is pliable enough to be Tight twine or Loose twist tie Triangular twine tie to bent in the other direction. twist tie at end along the cordon hold trunks together c nodes d of cordon Renewal spur internodes serves as a source 30” 30” of canes if it becomes necessary renewal spur to replace the cordon. loose twine tie Loose twine tie 66” 66” Double trunks Fig. 1 – Steps to training a grapevine to e the Hudson River umbrella (HRU) train- ing system: (a) an unpruned double- trunked vine after its second year of These canes are growth; (b) an expanded view of the top vertically oriented of a 2-year-old trunk indicating that the 30” because they were shoot cane at the top will probably not be positioned. useful because it will be girdled by the twine; (c) vine after pruning to retain the 66” long canes to establish cordons and renewal spurs; (d) vine after being tied to the trellis; (e) unpruned vine after its third growing season; (f) (see next page) vine after it is pruned and tied in preparation for its fourth growing sea- son and those thereafter. 5 Section 1 — The Structure of a Grapevine Figure 1 (continued) f Cordon Renewal zone 30” One-node lateral spurs on a large diameter cane Fruiting Renewal 66” canes spur Tight twist ties ous year are developing a rough-textured bark. After Renewal Zone, Renewal Spurs the leaves fall from the vine in the fall, the rough bark characteristic of the 2-year-old or older portions of the and Vine Space vine distinguishes them from the smooth-barked A vine must be managed to occupy its own specific current-year canes. space along a vineyard trellis. The portion of a trellis reserved for a vine is called its vine space. A vine is contained within its vine space through a combination Nodes, Internodes, Fruiting of vine management practices including choice of Canes and Fruiting Spurs training system, pruning, shoot positioning and fertil- ization. The renewal zone of a grapevine is the area Canes, the smooth-barked woody parts of the vine, within that vine space from which fruiting canes (or are very important to the grower. They have enlarged fruiting spurs, when these are used) originate. The areas along them called nodes (Fig. 1c). A node is a precise location and shape of a renewal zone will compound bud composed of: a primary bud, which depend on the vine training system being utilized. For typically produces two-thirds or more of the fruit; a example, when a modified 4-arm Kniffin training sys- secondary bud, which produces up to one-third of the tem is utilized (Fig. 3b), the fruiting canes originate fruit; and a tertiary bud, which produces little or no from a renewal zone in the middle of the vine space fruit (Fig. 2a). The smooth areas of a cane between near the top wire of the trellis. Therefore, in this the nodes are called internodes (Fig. 1c). Canes may example, an experienced pruner's eyes will concen- be pruned to varying lengths. If they are pruned to one trate on that portion of the vine to locate the desired to three nodes, they are called fruiting spurs.