Varieties and Rootstocks in Texas

Varieties and Rootstocks in Texas Pierre Helwi, Ph.D Extension Viticulture Specialist Texas A&M AgriLife Extension Service Grape Camp November 05, 2017

Characteristics of Major Types of Grapes Type Fruit Quality Potential Disease Resistance Flowering Cold Hardiness Vitis vinifera Excellent Poor Self fertile Low to moderate Native American spp Good Variable Self fertile High Hybrids Good Variable Self fertile Moderate to high Vitis rotundifolia Good Excellent Self fertile & female Low to moderate * Cold hardiness is the ability of a dormant grapevine to tolerate cold temperatures

Vitis Taxonomy Family Vitaceae Genus Vitis Sub-genus Euvitis Muscadinia Species Vitis vinifera Native American spp. Vitis rotundifolia Riesling, Syrah Concord Vidal blanc Inter-specific Hybrids * Varieties (noun); Varietals (adverb)

What Variety Should I Grow?

Criteria For Selecting Varieties 1. Market demand & Crop value 2. Disease susceptibility Pierce s disease 3. Timing of budbreak Susceptibility to spring frost 4. Growing season length V. vinifera V. vinifera 5. Cold hardiness 6. Vigor & Cluster architecture Blanc Du Bois V. rotundifolia

1. Market Demand & Crop Value Is the variety in demand by existing wineries or has potential for future demand? Talk to local wineries and other growers from your region Research Market saturation

1. Market Demand & Crop Value Is the variety in demand by existing wineries or has potential for future demand? Talk to local wineries and other growers from your region Research Market saturation What is the crop value (yield*value) of the variety? Does crop value consistently exceeds cost of production? Cabernet-Sauvignon: $2,000/ton x 3 tons/acre = $6,000/acre Chenin blanc: $900/ton x 8 tons/acre = $7,200/acre

2. Disease susceptibility Susceptibility to fungal and certain other pathogens: V. vinifera < Hybrids < Native American spp Type Fruit Quality Potential Disease Resistance Flowering Cold Hardiness Vitis vinifera Excellent Poor Self fertile Low to moderate Native American spp Good Variable Self fertile High Hybrids Good Variable Self fertile Moderate to high Vitis rotundifolia Good Excellent Self fertile & female Low to moderate

2. Disease susceptibility Pierce s Disease Is the vineyard in an area where Pierce s Disease exists? V. vinifera susceptible to Pierce s Disease Resistant or tolerant varieties with high productivity and good quality grapes e.g: Blanc Du Bois Black Spanish Andy Walker s selections 87 to 97% V. vinifera parentage (under evaluation) http://aggie-horticulture.tamu.edu/fruit-nut/files/2010/10/texas-grape-growers-pd-management-guide.pdf

3. Timing of budbreak Susceptibility to spring frost Is the vineyard prone to spring frost events? High risk of spring frost - Mid to late budbreak varieties Low risk of spring frost - Early or late budbreak varieties At the level of the entire region and spots in vineyard Early budbreak varieties: Gewürztraminer, Viognier, Concord Late budbreak varieties: Mourvèdre, Syrah, Tannat Frost Protection methods

3. Timing of budbreak Susceptibility to spring frost Is the vineyard prone to spring frost events? High risk of spring frost - Mid to late budbreak varieties Low risk of spring frost - Early or late budbreak varieties At the level of the entire region and spots in vineyard Other consideration Varieties capable of having secondary crop from secondary buds e.g. Pinot gris, Grenache, Cabernet-Sauvignon

4. Growing season length - Will a variety ripen at your site? Grape varieties ripen at different times of the season Match the length of the growing season with the variety Growing season with about 150 frost-free days: Early season or early to mid season varieties Example. Chardonnay, Pinot noir Growing season with more than 170 frost-free days: Mid season or mid to late season varieties Example. Petit verdot, Tannat, Cabernet-Sauvignon Planting a long-season variety at a site with only 150 frost-free days Planting a short-season variety in a hot region with long growing season

4. Growing season length - Will a variety ripen at your site? Grape varieties ripen at different times of the season Match the length of the growing season with the variety Growing season with about 150 frost-free days: Early season or early to mid season varieties Example. Chardonnay, Pinot noir Growing season with more than 170 frost-free days: Mid season or mid to late season varieties Example. Petit verdot, Tannat, Cabernet-Sauvignon How to determine the number of frost-free days? Number of days between last frost event and first frost event

Average Last Frost Date Map Average First Frost Date Map Zone 2: Jan. 21 Jan. 31 Zone 3: Feb.1 Feb. 10 Zone 8: March. 21 Mar. 31 Zone 9: Apr. 1 Apr. 10 Zone 8: Oct. 11 Oct. 20 Zone 9: Oct. 21 Oct. 31 Zone 13: Dec. 1 Dec. 10 Zone 14: Dec. 11 Dec. 20 Zone 4: Feb. 11 Feb. 20 Zone 10: Apr. 11 Apr. 20 Zone 10: Nov. 1- Nov.10 Zone 15: Dec. 21 Dec. 31 Zone 5: Feb. 21 Feb. 29 Zone 11: Apr. 21 Apr. 30 Zone 11: Nov. 11 Nov. 20 Zone 16: Jan. 1 Jan. 10 Zone 6: Mar. 1 Mar. 10 Zone 12: May 1 May 10 Zone 12: Nov. 21 Nov. 30 Zone 7: Mar. 11 Mar. 20 Zone 13: May 11 May 20 Plantmaps.com

5. Cold Hardiness - How cold is winter in the vineyard? Cold hardiness is the ability of a dormant grapevine to tolerate cold temperatures It is influenced by environmental and growing conditions, and varying among grapevine varieties and tissues Most V. vinifera are hardy to about 0 to -15⁰F e.g. Muscat: 0 to -10⁰F Cabernet franc: -5 to -15⁰F Hybrid varieties should be hardy -10 to -20 ⁰F e.g. Vidal blanc: -5 to -15⁰F Native American varieties should be hardy -30 to -40⁰F e.g. Concord: -15 to -25⁰F

Texas 2012 USDA Hardiness Zone Map Average annual extreme winter temperatures Zone 6b: -5⁰F to 0⁰F Zone 7a: 0⁰F to 5⁰F Zone 7b: 5⁰F to 10⁰F Zone 8a: 10⁰F to 15⁰F Zone 8b: 15⁰F to 20⁰F Zone 9a: 20⁰F to 25⁰F Zone 9b: 25⁰F to 30⁰F Zone 10a: 30⁰F to 35⁰F Most V. vinifera are hardy to about 0 to -15⁰F e.g. Muscat: 0 to -10⁰F Cabernet franc: -5 to -15⁰F Hybrid varieties should be hardy -10 to -20 ⁰F e.g. Vidal blanc: -5 to -15⁰F Native American varieties should be hardy -30 to -40⁰F e.g. Concord: -15 to -25⁰F Plantmaps.com

6. Vigor Be cautious of high vigor varieties/high vigor rootstocks/fertile sites Balanced vines Vigorous vines

6. Cluster Architecture Tight cluster versus Loose cluster Tight clustered varieties: Chenin blanc, Pinot gris, Petite Sirah, Grenache Loose clustered varieties: Syrah, Cabernet-Sauvignon Tight cluster Grenache Loose cluster Syrah

Rootstocks: Choosing the Right One

Own-rooted versus Grafted Vines Scion Graft union Rootstock Photo: Lake County Winegrape growers Photo: Reignac.com

Own-rooted versus Grafted Vines Own-rooted vines Used in sites where no threats presented by soil limitations, insects or pathogens Easy and inexpensive option if something catastrophic happens to the trunk, such as mechanical or severe freeze injury Grafted vines Used in sites with: - threats such as phylloxera, nematodes and soil-borne pathogens - physical and chemical soil restrictions: poorly drained sites, high lime levels, high ph, high salinity Rootstocks used to induce or reduce scion vigor

Choosing the right rootstock - There is no single universal rootstock that is suited for all situations - Rootstocks are often North American species or their hybrids. Almost all rootstocks are crosses between 3 north American species: V. riparia, V. rupestris and V. berlandieri - 3 characteristics that should be considered when making a selection: 1. Resistance to soil-borne diseases 2. Adaption to soil conditions 3. Influence on the scion

Choosing the right rootstock Rootstock Phylloxera Resistance Nematode Resistance Drought Tolerance Salinity Tolerance Lime Tolerance Vigor Potential Soil Adaptation 1103P High Med-High Med-High Medium Medium Med- High Drought & Saline Soil 5BB High Med-High Medium Medium Med-High Medium Moist Clay 110R High Low-Med High Medium Medium Medium Acid Soils SO4 High Med-High Low-Med Low- Medium Medium Low- Medium Moist Clay Match the rootstock characteristics with site and variety characteristics.

Choosing the right rootstock 1. Resistance to soil-borne diseases Potential loss from phylloxera infestation: use rootstock resistant to phylloxera Example. SO4, 5BB Presence of nematodes: use rootstock resistant to nematodes Several species of nematodes exist: use the proper rootstock Example. Root-knot nematode resistance: 5BB, Harmony Phylloxera Dagger nematode resistance: Ramsey, Freedom Test your soil before planting and ordering plant material Dagger nematode

Choosing the right rootstock 2. Adaption to soil conditions Drought: grapevines considered relatively tolerant to water deficit. Drought tolerant rootstocks enable the scion to grow and yield when water supply is limited Low drainage soils: where impermeable layer close to soil surface and high spring rainfall site Salinity: salinity of irrigation water and salinity associated with soils can be detrimental to vine health Alkalinity or acidity Calcareous soils: in soils rich in limestone, vines can suffer from lime-induced chlorosis

Choosing the right rootstock 3. Influence on the scion Vigor Rootstocks can induce or reduce scion vigor. For a balanced vine, match a high-vigor scion variety with a low to moderate rootstock and vice versa. Example. Sauvignon blanc (high-vigor scion variety) with 101-14Mgt (low to moderate rootstock) Improve nutritional status Yield and fruit quality: combination scion/rootstock improve quality

Conclusion - Choose right rootstock/scion combination - Don t try many varieties - Do not choose a variety or rootstock simply because it is available Order minimum 18 months before planting Reputable nursery - Certified plants - Seek the guidance of others with the variety you plan to plant, including fellow grape growers and viticulture advisors

Thank You For Your Attention! pierre.helwi@ag.tamu.edu Website: Aggie-horticulture.tamu.edu/vitwine Facebook: Texas Viticulture & Enology YouTube: Texas Agrilife Extension Enology - Texas A&M