Viticulture in Texas: the challenge of natural hazards

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Viticulture in Texas: the challenge of natural hazards a

b

Christi G. Townsend & Edward W. Hellman a

Department of Geography, Texas State University, San Marcos, TX, USA b

Department of Plant and Soil Science, Texas Tech University, Lubbock, TX, USA Published online: 27 Oct 2014.

To cite this article: Christi G. Townsend & Edward W. Hellman (2014) Viticulture in Texas: the challenge of natural hazards, Journal of Wine Research, 25:4, 211-228, DOI: 10.1080/09571264.2014.967338 To link to this article: http://dx.doi.org/10.1080/09571264.2014.967338

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Journal of Wine Research, 2014 Vol. 25, No. 4, 211–228, http://dx.doi.org/10.1080/09571264.2014.967338

Viticulture in Texas: the challenge of natural hazards Christi G. Townsenda* and Edward W. Hellmanb a

Department of Geography, Texas State University, San Marcos, TX, USA; bDepartment of Plant and Soil Science, Texas Tech University, Lubbock, TX, USA

Downloaded by [207.141.174.66] at 06:47 12 November 2014

(Received 28 January 2014; accepted 16 September 2014) Natural hazards present a ubiquitous challenge to the successful practice of viticulture. This article reports on the results of a research study conducted to ascertain the effects of natural hazards on viticulture in Texas. It examines the locational differences in the types of natural hazards that affect viticulture, as well as differences in mitigation techniques used by growers in different parts of the state. Results from an online survey indicate that most crop losses in Texas occurred as a result of multiple hazards having a cumulative effect over time. Analyses of survey data also show that viticultural crop loss as a result of one or a combination of natural hazards appears to affect Texas growers almost equally, regardless of prior professional experience (agricultural or non-agricultural) or whether a grower retains crop insurance. A thorough understanding of the types of hazards that may impact viticulture in Texas, along with the types of mitigation measures that are employed to combat those hazards, may prove invaluable those new to the field before the decision is made to invest in a new vineyard. Keywords: viticulture; natural hazards; Texas

Introduction Americans are showing a growing demand for fine wine, and the domestic production of this product has responded dramatically. As of 2009, the USA had over 380,000 ha planted with grapevines, ranking sixth in the world in terms of the area of land under vine and fourth in the world in wine production. The estimated retail value of wine sales in the USA was $30 billion in 2010 and in that same year, the USA surpassed France to become the number one wineconsuming nation in the world (Wine Institute, 2012). Growth in the Texas wine industry has also been extraordinary. The industry is young compared to more well-known grape-producing regions in the USA; however, Texas ranks fifth in wine production after California, Oregon, Washington, and New York, respectively. With a total economic impact of over $1.7 billion (an increase of 25% over 2007), viticulture and wine production have become important contributors to the Texas economy (Kane, 2012). As of 2007, Texas had over 220 vineyards totaling nearly 1500 ha planted, and more than 200 working wineries. This number represents an increase of over 300% in the last decade, and growth in the industry in Texas is showing no signs of slowing down. The Texas wine industry employs more than 8000 people (Kamas et al., 2008).

*Corresponding author. Email: [email protected] © 2014 Taylor & Francis


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Planting a vineyard can be expensive, both in terms of capital and labor. A commercially viable vineyard in Texas can cost between $11,000 and $15,000 per acre to plant, not including the price of land and equipment (Kamas et al., 2008). A number of environmental factors may unexpectedly complicate even the best laid vineyard plans, as an entire crop can be lost because of the impact of one or a combination of natural hazards. These hazards include, but are not limited to, drought, flooding and erosion, freeze or frost, extended periods of extreme heat or cold, hail, or strong winds. Biological hazards include fungal, viral, and bacterial disease, insect infestation, and damage from animals. The broad focus of this research was to explore both physical and biological natural hazards in vineyard settings and the associated impacts experienced by grape growers in Texas. The research sought to ascertain how Texas grape growers have prepared for, and responded to, environmental hazards in their vineyards. This research aimed to accomplish three primary goals: (1) to identify those hazards (both slow- and quick-onset) that present the most menacing threats to the successful practice of viticulture in Texas, (2) ascertain whether a difference exists regarding hazard mitigation strategies in different growing regions of Texas, and (3) determine whether there is a discernible trend in successful hazard mitigation and adaptation among growers with extensive agricultural experience versus those who are new to the profession. Growers’ interactions and relationships with the land, with each other, and the consistency (if any) with which growers manage natural hazards are also considered. Agricultural experience (both extent and duration) is taken into account with an attempt to draw statistically significant comparisons among growers with less experience in agriculture (i.e. those for whom viticulture is a second profession or retirement venture) versus those growers who have been employed in the practice of viticulture or another type of agriculture long-term or as their primary profession. An online survey disseminated to 281 grape growers located throughout the state was the primary data collection instrument. The survey assessed, in part, whether there was a locational difference in the types of natural hazards that affect viticulture, as well as whether there was a difference in the mitigation techniques used by growers in different parts of the state and among growers with differing levels of experience. Though the reasons for current and past research in natural hazards are pragmatic, geographic research has historically tended to focus on quick-onset hazards and hazards resulting in disaster (Mitchell, 1989). Hazards that may impact agricultural operations may include both quick-onset hazards and slow-onset hazards which can be biological or geophysical in nature. Few hazards geographers have considered the effects of natural hazards on viticulture (Belliveau, Smit, & Bradshaw, 2006; Hansis, 1977). This research seeks to partially fill this gap. Viticulture in Texas: a brief history and current state of the industry Viticulture is not new to Texas. Before the arrival of Europeans to Texas, indigenous peoples harvested and consumed native grapes, which grew prolifically in many parts of the state (Kane, 2012). Wine has been produced to some extent in Texas since the 1600s when Spanish missionaries began cultivating Mission grapes near what is present-day El Paso. European immigrants planted vineyards in south and central Texas; cultivating cuttings brought with them from their homelands. By 1919, 50 working wineries existed in Texas, but all were forced to cease operation with the ratification of the 18th Amendment to the US Constitution, the Volstead Act, commonly known as Prohibition (Kane, 2012). Val Verde winery in Del Rio, Texas, founded in 1883, is the only winery that survived Prohibition and remains open today (Kamas et al., 2008). Thomas V. Munson, a horticulturalist and prominent historical figure in the world of viticulture, is widely considered as the ‘father of Texas grape culture’. Munson worked with both wild and cultivated grapes adaptable to the southern USA (Perry & Bowen, 1974) and is celebrated for his assistance in restoring the vineyards of France after the devastating phylloxera outbreak of the


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late nineteenth century by the provision of phylloxera-resistant American rootstock. After Munson’s death in the early 1900s, little research occurred in Texas until the 1930s, when experiments with table grape varieties were carried out through the 1950s in South Texas and the Rio Grande Valley (Perry & Bowen, 1974). Viticulture of premium wine grapes did not return on a significant scale until the 1970s when researchers at Texas A&M University, Texas Tech University, and the University of Texas began experimenting with test vineyards, finding that some grape varieties, mostly French-American hybrids, could grow successfully in the drier regions of Texas with adequate irrigation. The industry in Texas has experienced considerable growth in the last three decades. One commercial winery existed in Texas in 1975 (Morse, 1990). Today, more than 200 commercial wineries exist in the state. According to a survey conducted by the USDA National Agricultural Statistics Service (NASS) and the Texas Wine Marketing Institute, 2010 was the best grape production year in Texas since the 2005 season. The estimated value of the production was $10,657,000; the highest value in the last decade. The leading grape varieties (based on bearing hectares) planted in Texas in 2010 were Cabernet Sauvignon, Chardonnay, Chenin Blanc, and Merlot, accounting for 35% of the state’s total utilized production (United States Department of Agriculture, 2011). American viticultural areas in Texas Eight federally registered viticultural areas currently exist in Texas (Figure 1). They include Bell Mountain, Fredericksburg in the Texas Hill Country, the Texas Hill Country, Escondido Valley, Texas High Plains, Davis Mountain, Mesilla Valley, and Texoma. The oldest and smallest at approximately 13 km2 is the Bell Mountain viticultural area, ensconced completely within the boundaries of the Texas Hill Country viticultural area and established in 1986. The largest at approximately 39,000 km2 is the Texas Hill Country viticultural Area, located in central Texas. Although most vineyards are found in one of the listed American viticultural areas (AVAs), not all vineyards in Texas are located in an established AVA. Natural hazards definitions Natural hazards are defined as hazards which may be triggered by natural, extreme events and are at least partly beyond human control (Palm, 1990). It is not the event itself, but the interaction of the event and humans, that produces the hazard (Kates, 1971; White, 1988). Natural hazards may be geophysical (meteorological and geological) or biological (floral or faunal) in nature (Burton, Kates, & White, 1993), and can be quick in onset (e.g. severe thunderstorms) or slow in onset (e.g. drought). Natural hazards are not always necessarily detrimental. For example, a flood may act to fertilize fields, a drought may help to clear fungal outbreak, or a freeze may kill potentially harmful insects. Natural hazard perception is defined as the expectation of future occurrence and personal vulnerability (Kates, 1971). Natural hazards are a function of four interacting variables: risk, exposure, vulnerability, and response (Mitchell, 1989). Risk is defined broadly as the probability of an extreme event. Exposure is a measure of the population at risk. Vulnerability is essentially the potential for loss and is a corollary of seeking beneficial use of land resources (Burton et al., 1993). Response is the choice of measures to avoid, reduce, or prevent loss. Limiting factors for viticulture in Texas: biological hazards Grapes are susceptible to a great number of diseases, making the practice of commercial-scale viticulture in Texas challenging. Some diseases are so severe that vineyards simply cannot be


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Figure 1. American viticultural areas in Texas.

grown in geographic locations where the disease is present (Winkler, Cook, Kliewer, & Lider, 1974). Anthracnose, Black Rot, Bunch Rot, Cotton Root Rot, Crown Gall, Downy Mildew, Powdery Mildew, and Pierce’s Disease are some of the diseases that have the potential to infect grapevines. Pierce’s Disease, arguably the greatest disease hazard to grapes in Texas, is caused by a bacterium, Xylella fastidiosa, which is transmitted by insect vectors. It has been known to cause significant losses in many Texas vineyards (Kamas, Black, Appel, & Wilson, 2008). High humidity (a common weather occurrence in Central and South Texas) contributes to the vulnerability of vine canopies to develop bunch rot and other fungal diseases. More than 50 different insect species attack grapevines and their fruit (Winkler et al., 1974). Phylloxera, grape berry moth, grape June beetle, glassy-winged sharpshooter, grape cane borer, mealy bugs, and thrips are examples of the insect pests that have the potential to damage grapevines and their fruit. Birds and mammals, including deer, raccoons, squirrels, mice, and rabbits, are some of the larger pests that exhibit a preference for the fruit and habitat a vineyard can offer.

Limiting factors for viticulture in Texas: geophysical hazards Weather conditions in a given location often govern whether grapes can be successfully grown (Winkler et al., 1974). Weather-related hazards in Texas may include periods of heavy rainfall


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and flooding, soil erosion, humidity, hail, wind, lightning, freeze or frost, drought, periods of extreme heat or cold, and fire. These hazards have the potential to occur in all Texas grapegrowing regions, though some are more tied to the geography of specific regions. For example, susceptibility to sudden periods of heavy rainfall, combined with sparse vegetation, steep and hilly topography, and shallow soils, have earned the Texas Hill Country region of Central Texas the popular designation, ‘Flash Flood Alley’. Vineyards in the Hill Country are often located near water bodies, including creeks and streams, rivers, lakes, or intermittent drainages, and are thus vulnerable to this particular geophysical hazard.


Study area The study area for this research encompassed the entire state of Texas. Texas is one of the southernmost states of the USA, sharing a southern border with Mexico and the Gulf of Mexico. It is the largest of the 48 contiguous states with an area of approximately 692,000 km2 and given its size, exhibits a great variety of landscapes, climates, terrains, geologies, and soil-types (Prout, 2012). The highest elevations are generally found toward the northern and western parts of the state, descending gradually toward a sea level at the coast. Texas exhibits more than 800 recognized soil series (Jordan, Bean, & Holmes, 1984). The Texas Wine and Grape Growers Association (TWGGA) devised a system of regions to encompass the entire state, which closely follows the major physiographic regions of Texas. This research adopted these regional designations as a spatial template for study, so that all growers who participated in the study could be accounted for regardless of whether they own vineyards in an AVA. The TWGGA map consists of the following regions: Hill Country (Central Texas), Southeast Texas (Gulf Coast), Texas Panhandle (High Plains), North Texas (Dallas/Fort Worth area), and West Texas (Figure 2).

Figure 2. Texas Wine and Grape Growers Association Regions.

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Methodology The goal of survey research is to gain an understanding of the characteristics, attitudes, and behaviors of a population by administering a questionnaire to a sample of individuals (McLafferty, 2003). An online survey was deemed to be the most appropriate method for primary data collection because this research sought, in part, to gain a better understanding of grape grower awareness, adaptation, and mitigation related to natural hazards. The survey was disseminated via email to 281 grape growers using an email list generated by extension viticulture program specialists located in regional offices throughout the state. Administration of the survey questionnaire was immediately preceded by an invitation to participate, in the form of a brief letter sent to vineyard growers (owners or operators) as an attachment to the email. This letter briefly described the purpose of the research and included contact information for the researchers. The survey was password protected in order to prevent random internet users from compromising the results. The invited growers were given six weeks to complete the survey and email reminders were sent three separate times during that six-week period to augment participation. The questionnaire was designed to be quick and simple to complete and consisted of a combination of dichotomous (yes or no) questions yielding nominal data, questions presented in a five-point Likert scale format providing ordinal data, followed by open-ended interview questions providing qualitative data. The inclusion of open-ended questions allowed for unanticipated responses and was meant to allow each grower to speak on the topic in his or her own voice and focus on what was meaningful or important in their own unique situation (Fowler, 1993). The responses to the open-ended questions were qualitatively examined for recurring themes in an effort to garner meaningful information. The survey included a list of natural hazards that could potentially impact Texas vineyards (e.g. wildfire, drought, hail, freeze/frost, etc.). The participants were given a list of potential responses for each hazard presented in a Likert scale format (never, rarely, occasionally, frequently, or unsure). This was done to gain information on the types of natural hazards affecting viticulture, frequency of occurrence, and whether they were spatially concentrated. As a means of recording physical traces of behavior, the survey included questions meant to determine adaptations for use, which are intentional changes to the environment that are meant to make a place more functional (Montello & Sutton, 2006). The survey also asked questions about the strategies growers have employed to prepare for, or mitigate, natural hazards and whether these strategies were successful. The growers were also asked about the resources they regularly consult (governmental organizations, county extensions, books, etc.) when seeking help or guidance in controlling natural hazards. Twenty years of historical crop loss data were also analyzed to ascertain the causes and magnitudes of grape crop losses in Texas, and as a means to verify survey results. This data came from crop losses reported to crop insurance programs and is available from the United States Department of Agriculture Risk Management Agency. A mixed-methods approach was employed with respect to the analysis of the data. The sample size was expected to be relatively small; therefore, inferential, non-parametric statistics were used to analyze the data. Descriptive statistics were used to answer other questions for which inferential statistics were inappropriate or for which the sample size was inadequate.

Limitations of data Every possible effort was made to achieve a high survey response rate. However, by virtue of the time required to fill out the survey (estimated to be approximately 15 min) and the individual


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personality characteristics of the growers, not every grower invited was expected to participate. Reactance is a significant short-coming associated with the collection of interview or survey data (Montello & Sutton, 2006). Under survey conditions, especially in which anonymity is not a factor, a person’s answer may change from what otherwise would be their true response because they realize they are being measured or observed. The vineyard names and identities of those who completed the survey are being kept confidential. However, it was necessary to know the general location (address, city, and/or county) of each survey response in order to map natural hazard regions, thus diminishing the anonymity factor. This may have introduced some bias into the findings of this study. Another potential source of bias may be the fact that the data gathered are based on the personal opinions and individual perceptions, and may not accurately reflect environmental conditions as they actually exist in their vineyards. For example, one grower’s perception of what constitutes severe damage from a hail storm may differ from another grower, who might perceive the same level of damage to be minor.

Results A total of 112 growers participated to some degree in the online survey (40% response rate). Seventy-four percent of respondents completed the entire survey (answered all possible questions). Others who did not completely finish the survey but answered some questions were included in certain analyses if the information they submitted was sufficient to answer a specific research question. The majority of participants own vineyards in either the Central Texas/Hill Country TWGGA region (46) or the Texas High Plains region (20). Eighteen participants own vineyards in the North Texas region, 16 were located in the Gulf Coast region, and 4 own vineyards in the West Texas region. Approximately half own vineyards in an AVA, including 37 in the Hill Country AVA, 18 in the High Plains AVA, and 4 in the Texoma AVA. Two participants chose not to reveal the location of their vineyard(s). Most growers (approximately 90% of respondents) own only one vineyard. Nine participants reported owning more than one vineyard. The average vineyard size for the entire state was 6.4 ha (15.8 acres), with a minimum size of 0.04 ha (0.1 acre) and a maximum size of 93 ha (230 acres). The average vineyard sizes by region are reported in Table 1. The respondents came from a variety of professional backgrounds and ranges of experience (Figure 3). The overall minority were life-long farmers. Others included current or former physicians, computer/information technology/software professionals, engineers, scientists, attorneys, military personnel, educators, business owners and executives, a venture capitalist, a pharmacist, and an airline pilot. The majority of participants (66%) do not own wineries; rather they grow grapes for sale to wineries or for personal consumption (hobby vineyards). Six participants fell into the ‘hobbyist’ category and they tended to own vineyards less than 0.4 ha (one acre) in size. Table 1. Number of respondents and average vineyard sizes by region. Region Hill Country High Plains North Texas Gulf Coast West Texas

Number of respondents

Average vineyard size (ha)

Total regional hectares (for sample)

46 20 18 16 4

4.96 14.1 1.8 1.1 26.3

223.1 282.2 31.7 17.5 105.2

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Figure 3. Agricultural experience (in years) indicated by survey participants.

Viticultural natural hazards in Texas The survey included a list of 15 biological and geophysical hazards having the potential to impact vineyards in Texas. The hazards included were, in no particular order, disease (bacterial, viral, and fungal), birds and other types of animals, late spring freeze (after bud break), extreme cold winter temperatures, extended periods of extreme heat, strong/damaging winds, lightning, hail, soil erosion, flooding, drought, and wildfire. A Likert scale was included with each hazard with five answer options from which the participants could choose based on how often they had experienced each hazard. The results show that there are some hazards which have historically affected more growers compared to others. State-wide, drought, hail, damaging winds, disease, birds and other wildlife, insects, late spring freeze, and extended periods of extreme heat appear to be the hazards Texas growers most frequently encounter. The least common hazards encountered included wildfire, flooding, soil erosion (erosion from wind and water), and lightning. The results from the Likert scale portion of the survey are also reported with choropleth maps created using geographical information system software (ArcGIS) and show hazard intensity, as experienced by growers, by location (county). This was done to spatially represent where problems associated with certain natural hazards have been concentrated. Hazard intensity maps for the bird hazard, fungal disease hazard, and extreme cold hazard are shown to illustrate spatial variation in hazard intensity (Figures 4–6).

The most menacing hazards by region The survey participants were asked to identify the one hazard they felt was the most troublesome in their vineyards. Growers in all regions, with the exception of the High Plains, recognized biological hazards to be the most menacing. Central Texas/Hill Country growers (71%) reported animal-related damage to be the most significant hazard, followed closely by fungal disease, Pierce’s Disease, and insects. Similarly, 88% of growers in the Gulf Coast region chose biological hazards to be the most menacing. Fungal disease was chosen most often, followed closely by bird and animal damage. Growers in North Texas cited fungal disease as the most troublesome hazard, followed by birds, raccoons, and other wildlife. The four West Texas growers listed birds and other animals, crown gall, and extended periods of extreme heat as the most troublesome hazards. The trend was reversed for the High Plains, where the predominance of growers (75%) indicated that geophysical hazards, including late spring freeze, hail, wind, drought, and severe winter cold temperatures were the most troublesome viticultural hazards.



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Figure 4. Map illustrating the relative frequency of the bird hazard by county.

Mitigations strategies for the most menacing natural hazards Mitigation strategies employed for natural hazards were generally inconsistent across all regions. Ten different mitigation measures were listed for late spring freeze and are listed in Table 2 by region. The most commonly used mitigation strategy for late spring freeze for all regions was late pruning (waiting to prune canes for as long as possible before the emergence of new growth). No mitigation strategies for late spring freeze were listed by growers in West Texas or the Gulf Coast region. Birds were, by far, the most significant animal to cause vineyard damage and, therefore, were considered separately. Mitigation strategies for control of birds were slightly more consistent (Table 3). Strategies included passive, active, and chemical measures. Although 12 different mitigation methods were mentioned, the majority of growers use netting to control for bird damage. Wildlife damage, in general, was listed frequently as a hazard by Texas growers, especially by those in the Hill Country. Troublesome animals included deer, raccoons, squirrels, gophers (in the High Plains), feral hogs, and rabbits. Combinations of active, passive, and chemical measures are used to control for animal damage (Table 4). High game fencing and shooting (to scare and/or to kill) were more commonly used. Correct disease identification is imperative when choosing a mitigation method, as successful treatments are highly dependent on the type of disease infecting the vine. Six different strategies were listed by survey participants for disease mitigation (Table 5). The scheduled application of chemical sprays was reported to be the most common and successful approach to combating disease. Experimentation with different types of rootstock, removal of infected sections, and complete vine removal were also common strategies.


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Figure 5. Map illustrating the relative frequency of the fungal disease hazard.

Figure 6. Map illustrating the relative frequency of the extreme cold temperature hazard.


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Table 2. Mitigation strategies listed for the late spring freeze hazard. Mitigation strategies for late spring freeze High Plains

Hill Country/Central Texas


North Texas

Late Pruning (4) Double Pruning (2) Cover Crops Winter Irrigation Proper Site Selection Burning Hay Bales (4) Aerial Sprinklers Wind Machines ‘Kocide’ (Copper) Spray Late Pruning Late Pruning Planting of Late Bud-break Varieties

Table 3. Mitigation strategies listed for bird damage. Mitigation strategies for bird damage High Plains


Gulf Coast North Texas

West Texas

Netting Dogs Noise Makers Shooting Netting (6) Strobe Lights Shooting Dogs Mylar Streamers Plastic Owls Netting (3) Repellants Netting (2) Shooting Scarecrows DVDs Hung on Trellises Netting (2) Propane Cannons Balloons Electronic Noise Making Devices

Crop losses caused by natural hazards The survey participants were asked whether they had experienced an economically significant crop loss as the result of one or a combination of natural hazards. Sixty-four (approximately 68%) respondents indicated that they had experienced at least one major crop loss and all owners (100%) of multiple vineyards reported an economically significant crop loss. Statewide, the number one cause of crop loss was late spring freeze/frost (listed 28 times) followed closely by wildlife damage (listed 21 times). Drought ranked third as a significant cause of crop loss, followed by hail and disease. Combinations of natural hazards having a cumulative effect were most often responsible for significant crop losses. Rarely was a single hazard listed as the sole cause of a crop loss in any given year (Figure 7).

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C.G. Townsend and E.W. Hellman Table 4. Mitigation strategies listed for animals other than birds. Mitigation strategies for animal damage (deer, raccoons, squirrels, gophers, feral hogs, and rabbits) High Plains

Shooting (2) High Fencing Poison Traps (4) Shooting (3) High Fencing (3) Electric Fencing (2) Dogs Traps (5) Shooting (3) High Fencing (2) Electric Fencing Poison High Fencing (2) Shooting (2) Scarecrow Repellants Electric Fencing Hanging soap from trellises Shooting Cannons Dogs



Gulf Coast

North Texas

West Texas

Breaking down the results by region, the High Plains reported hail to be the most common cause of crop loss. The most common cause in the Hill Country/Central Texas was animal damage (most often birds and raccoons). No majority hazard was responsible for crop loss in the Gulf Coast region, with late spring freeze and animal damage garnering an equal number of votes. North Texas growers most often listed late spring freeze as the most common cause of crop loss. West Texas growers, of which there were only four who participated, reported disease, late spring freeze, and extreme winter cold as causes of crop loss. It should be noted that the most menacing natural hazard reported by growers was not always the hazard that caused a significant crop loss.

Table 5. Mitigation strategies listed for disease. Mitigation strategies for disease High Plains Hill Country/Central Texas

Gulf Coast North Texas West Texas

Chemical Spray Application Change of Rootstock Chemical Spray Application (13) Removal of Infected Sections (3) Change of Rootstock Change of Grape Variety Vine Removal Chemical Spray Application (5) Change of Rootstock Chemical Spray Application (6) Change of Rootstock Integrated Pest Management Deficit Irrigation Soil application of potassium



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Figure 7. The most common causes of crop loss state-wide.

Twenty years of historical crop loss secondary data (1991–2010) for grapes, reported by crop insurance agencies, were collected from United States Department of Agriculture Risk Management Agency. These data were analyzed to ascertain the causes of grape crop loss in Texas and were compared to the survey results. Historical crop loss data were available for 19 counties, the majority of which were located in the High Plains (9) and Hill Country/ Central Texas region (6). Two counties were located in the North Texas region and two were located in the West Texas region. Ten causes of crop loss were reported for the 20year period. They included, in order of frequency of occurrence: freeze and frost (110); hail (71); excess moisture/precipitation (17); heat (16); wildlife (11); hot wind (8); wind (5); insects (4); fire (1); and plant disease (1). The two most frequent causes of crop loss during the 20-year period for the High Plains were Freeze (71 reports) and Hail (50 reports). Growers in Lubbock County reported the most crop losses of any county in the High Plains region over the 20-year period (Table 6).

Table 6. High Plains crop loss causes reported in 5 year increments for a 20-year period beginning in 1991 and ending in 2010, based on crop insurance claim data from the United States Department of Agriculture Risk Management Agency. Texas high plains: viticultural crop loss by hazard Year span 1991–1995 1996–2000 2001–2005 2006–2010

Most reported hazard Freeze (25) Hail (13) Hail (14) Freeze (27)

Second most reported hazard Hail (13) Freeze (7) Freeze (12) Hail (10)

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Table 7. Hill Country/Central Texas crop loss causes reported in 5 year increments for a 20-year period beginning in 1991 and ending in 2010, based on crop insurance claim data from the United States Department of Agriculture Risk Management Agency. Texas Hill Country/Central Texas: viticultural crop loss by hazard


Year span 1991–1995 1996–2000 2001–2005 2006–2010

Most reported hazard Hail (5) Freeze (6) Freeze (4) Freeze (8)

Second most reported hazard Wildlife (3) Hail (3) Hail (1) and Excess Moisture (1) Hail (3)

The frequent causes of crop loss during the 20-year period for the Hill Country/Central Texas were slightly more variable. Freeze (18) and Hail (12) were the two most common reported causes of crop loss for the 20-year period. Other major hazards to cause crop losses were reported to be wildlife, excess moisture/precipitation, and heat. Growers in Runnels County reported the most crop losses of any county in this region (Table 7).

Analysis of the crop loss and agricultural experience relationship To determine whether there was a relationship between agricultural experience and crop loss, it was first necessary to assign a code to the respondents. Those for whom agriculture (viticulture or otherwise) was a life-long profession (n = 19) were coded as ‘agriculture’; and those for whom viticulture is a retirement/second career or hobby (n = 80) were coded as ‘non-agriculture’. A phi coefficient statistical test was utilized to determine whether there was an association between crop loss and agricultural experience. This type of non-parametric statistical test measures association between dichotomous variables using a contingency table (Table 8). A phi coefficient of −0.04 was calculated, which relates to a chi-square (χ 2) statistic of 0.16. Comparing the resulting chi-square statistic with tabulated chi-square values with one degree of freedom, it was shown that 0.16 < 3.841; therefore, there was a failure to reject the null hypothesis of no association between the two variables. The results from this analysis suggest that there may be no association between crop loss and whether a grower came from an agricultural or other professional background before embarking on a career in viticulture. Crop loss from all causes appears to affect growers in Texas almost equally, regardless of prior professional experience.

Analysis of the crop insurance retention and crop loss relationship The respondents were asked whether they retained crop insurance to help absorb the costs associated with a major crop loss. Grapevines are eligible for crop insurance if they are four years old (fourth leaf) or older and growers must also show the capacity to produce a minimum tonnage of Table 8. Contingency table comparing crop loss and prior agricultural experience. Crop loss and agricultural experience Prior experience Agriculture Non-agriculture Total

Crop loss (yes) 12 55 67

Crop loss (no) 7 25 32

Total 19 80 99


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Table 9. Contingency table of survey results comparing crop loss and insurance retention. Crop insurance retention and crop loss


Insurance retention Insurance No insurance Total

Crop loss (yes) 11 58 69

Crop loss (no) 3 29 32

Total 14 87 101

grapes. Of the 101 respondents who answered this question, 14 retained crop insurance (14%). Of the 14, 11 had experienced a major crop loss and 9 had deemed the crop loss significant enough to file a claim on their crop insurance (Table 9). A phi coefficient statistical test was used to determine whether there was an association between crop loss and retention of insurance. A phi coefficient of 0.09 was calculated, which relates to a chi-square (χ 2) statistic of 0.79. Comparing the calculated chi-square statistic with tabulated chi-square values with one degree of freedom, it was shown that 0.79 < 3.841; therefore, there was a failure to reject the null hypothesis of no association between the variables. It can thus be concluded that there was no association between crop loss and retention of crop insurance.

Discussion Arguably, the most important finding from this study is that most crop losses in Texas are a result of multiple natural hazards having a cumulative effect. Rarely was a single natural hazard reported as the cause of a significant crop loss. For example, a vineyard may lose 20% of their crop to a late spring freeze/frost, then an additional 10% to a mid-summer hail event, and another 10% to bird damage before harvest. Growers from all over the state seemed to show a high degree of awareness and understanding of the major hazards that impact viticulture in Texas, but their range of adaptation to and mitigation of the hazards was inconsistent. It is possible that successful mitigation of natural hazards may be controlled by geography. In other words, measures that may work well in the Gulf Coast region may not work as successfully in West Texas or the High Plains. For example, given that soils differ in each of the regions, the application of a chemical or element to soil in a West Texas vineyard as a method to control disease may not work as efficiently when applied to a differing soil type occurring in a Gulf Coast vineyard. The vineyards with the most significant losses associated with biological hazards (disease and wildlife) appeared to be concentrated toward the eastern, southern, and central areas of the state. A map of average annual precipitation for Texas illustrates a spatial trend that may be associated with the types of losses experienced (Figure 8). Moisture in the form of precipitation tends to be concentrated toward the east. There is an important relationship between the geographic distribution of rainfall and the incidence and severity of biotic hazards, as higher rainfall supports more vegetation, more animals, and more diseases (with the exception of powdery mildew, which tends to be more prevalent in drier climates). Vineyards in the High Plains and West Texas are primarily dealing with powdery mildew, which is generally easier to control with fungicides. This may be an important reason why late spring freeze and hail are of greater concern to growers in the High Plains and West Texas. The next logical step for growers and viticultural researchers may be to determine consistent and geography-specific approaches for the mitigation of the hazards most likely to impact vineyards in each of the growing regions in Texas.


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Figure 8. Map of average annual precipitation in Texas.

A strong sense of camaraderie seems to exist among Texas grape growers, as well as a strong desire for the industry to survive and thrive. No association between crop loss and agricultural experience was found, but this is not surprising given the opportunities for free or inexpensive help in the form of advice and training available through extension services, trade association programs and workshops, and/or consultants. Several growers revealed that they regularly share information via email groups and by phone. Seventy-one percent of respondents reported that they regularly go to other Texas grape growers for help and/or advice. To describe the grape industry in Texas as competitive in an antagonistic sense would be inaccurate. Many aspects of the winemaking facet of the industry remain ‘proprietary’, but the growers themselves are not secretive; rather they seem to freely share their experiences laboring in the environment in which they have chosen to plant their grapes, and they seem to be keenly aware of the experiences of their competitors. The distribution of this ‘free advice’ may have something to do with the absence of a correlation between agricultural experience and crop loss. These relationships are what likely most influence their choices of adjustments to natural hazards and may become increasingly important as government funding for county extension viticulture advisors is threatened. Further examining the relationship between crop loss and agricultural experience, it should be noted that this analysis focused on all natural hazards, those that could be mitigated and those for which mitigation is very difficult or impossible. There was an assumption that growers with longterm experience have more knowledge of mitigation practices and therefore would be able to avoid crop losses more often than growers with less experience. This could be a valid assumption with some of the more controllable hazards, such as disease and birds. However, it should be noted that there are some hazards (e.g. geophysical hazards such hail and late spring freeze/ frost) for which no truly effective mitigation measures exist. A more detailed examination of the data revealed that, for the more experienced growers (growers for which agriculture is a life-long profession) who indicated the cause of their significant crop loss, all but one had



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experienced that loss as a result of hail or late spring freeze, natural hazards for which successful mitigation is incredibly difficult. Of the less experienced growers (retirement, hobby, or second career), 23 (approximately 43%) experienced a crop loss as a result of a controllable biological hazard (disease or wildlife damage). This finding suggests that the more experienced growers are indeed more successful in mitigating the biotic hazards. Though the statistical analyses indicated that there may not be an association between crop loss from all causes and experience, it appears that more experienced growers are more successful in mitigating specifically the biotic hazards. Geophysical hazards (e.g. hail, late spring freeze) seem to impact growers more equitably. A test of the association between crop loss and crop insurance retention did not reveal a statistically significant association between crop loss and whether the grower retained crop insurance. Crop insurance for grape growers is typically paid as a flat rate percentage of the crop that is lost, which only slightly lessens the financial burden. The brunt of the agricultural risk is still absorbed by the grower and sometimes by the winery if the winery has invested in the crop. Texas grape growers are not dependent on insurance, rather they will likely mitigate for hazards with the same intensity as if they had no insurance at all.

Conclusion From the crimson soils of the High Plains, to the deep, black, prairie soils of the Gulf Coastal Plain, the terroirs of Texas produce unique wines for which Texans are showing a fondness and the wine industry continues to expand to fulfill this growing preference. New wineries and vineyards are appearing on the landscape every year and the bucolic scenery of the wine regions of Texas promises an ever increasing tourist presence, and with the tourists comes the prospect of copious retail sales (Kamas et al., 2008). For Texas growers, these benefits outweigh the agricultural risks. However, in its relatively short history, many grape crops in Texas have been severely impacted or destroyed by one or a combination of natural hazards. Although some could not have been foreseen or avoided, others may reflect lack of knowledge, foresight, or preparation. This research was completed in order to further quantify and understand the effects of, and trends associated with, natural hazards on Texas vineyards. The results from this study will hopefully shed new light on decision-making trends as a whole for the grape-growing industry in Texas. Late spring freeze was the natural hazard that has consistently been shown to be responsible for most grape crop losses in Texas. Therefore, future research should focus on how to best mitigate this particular hazard. The results from this study also show that the different growing regions of Texas contend with their own unique sets of hazards. Some regions (constrained primarily to northern parts of Texas) struggle more with geophysical hazards and others (mainly those in the southern parts of Texas) contend more often with biological hazards. Since mitigation of these hazards requires a significant monetary investment, understanding the geography of these hazards will help growers in different areas of the state to better understand which hazards they should focus most of their attention and funds. Decision-making throughout the process (from choosing appropriate vineyard sites and grape varieties to management of natural hazards in the vineyard) may determine future impacts of natural hazards on viticulture in Texas.

Acknowledgements The authors would like to acknowledge the grape industry of Texas for their willing participation in this study and the Texas A&M University Agrilife Extension Service for their help in the distribution of the

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survey instrument. The authors would also like to acknowledge Ms Amy Snelgrove with the Texas A&M AgriLife Extension for her assistance with the geospatial data used to create the Texas Viticultural Areas map. Finally, we appreciate the comments made by two anonymous reviewers, which helped to significantly improve the manuscript.


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