- Fruits: grapes
- Animals: sheep
- Crop Production: application rate management
- Education and Training: technical assistance, demonstration, extension, focus group, on-farm/ranch research
- Pest Management: integrated pest management
- Production Systems: agroecosystems, integrated crop and livestock systems
The purpose of this project was to train vineyard managers and sheep producers the practices and techniques of vineyard floor grazing and grape leaf aversion training in sheep, to apply sheep grazing in vineyards and to document feedback from project participants. Three project workshops/field days were held, plus private aversion training sessions on four farms. As a result of this project, approximately 17 vineyards are now using sheep grazing on a regular basis, and four are using averted sheep for spring vineyard floor management. An instructional DVD on vineyard grazing practices is being developed for release in 2012.
Grape production in California requires diligent management of the vineyard floor. This involves weed control practices and may include the use of cover crops. Pre-emergent and/or post-emergent herbicides and cultivation are the primary methods of weed control in the vine rows (the area directly below the vines), while vegetation control in the middles can be accomplished with a combination of mowing and cultivation. Cover cropping in the vineyard middles is a practice often used to reduce soil erosion and to improve soil characteristics. Weeds and cover crops become quite competitive with grapevines beginning in the late spring and early summer. Vineyard floor management practices are used to reduce this competition to ensure healthy vine growth. In addition, a tall plant cover on the vineyard floor increases the risk of spring frost damage to the vines. Developing alternative practices to herbicides, mowing and cultivation can reduce health and environmental risks and may provide savings in vineyard floor vegetation management costs.
Sheep grazing is a cultural practice to manage the vineyard floor that is growing in use and acceptability. Several vineyards in California’s wine growing regions have been experimenting with sheep grazing and have adopted the practice to supplement other floor management practices. Sheep can eliminate the need for herbicides, and they can be used in vineyards rain or shine. Currently, the biggest impediment to their use is the fact that sheep like to browse the spring growth of grapevines. Some vineyards work around this problem by using Babydoll Southdown sheep, which are too short to reach the vines. Vineyard managers are pleased with the results, but the use of these miniature sheep is very limited due to their rarity and consequently high price. Other vineyards are using normal commercial sheep, but only by placing electric fencing around each vine row or by limiting grazing to times of the year when the vines are not susceptible to sheep damage, such as between the time of harvest and the emergence of new spring growth.
This problem can be mitigated by training sheep to have a dietary aversion to grape leaves, which will extend the time sheep can graze in vineyards through the spring months when weed and cover crop vegetation grow most vigorously. Sheep grazing is a reduced risk alternative to herbicide applications and is an attractive option for sustainable, organic and biodynamic grape production programs. The technique used to train a grape leaf aversion in sheep is based on research led by Dr. Fred Provenza at Utah State University. Dr. Provenza demonstrated that lambs acquired aversions to nutritious grains by giving the lambs an oral dose of lithium chloride (LiCl) immediately after eating the grains.
In June 2007, our project team concluded a one-year project demonstrating that sheep with a trained aversion to grape leaves can be used for managing spring vineyard floor vegetation. Sheep were trained with the aversion in June 2006 and were then used for spring vineyard grazing in 2007. Preliminary results show that averted sheep have almost no negative impact on the grapevines due to browsing compared to non-averted sheep that significantly damaged the vines.
The next phase was to apply grazing practices with averted sheep in commercial vineyards in order to better understand the challenges, limitations and improvements to the practices on a larger and commercial scale. This Western SARE grant funded workshops, groundwork and outreach efforts to accomplish this next phase.
The goal of this project is to integrate producers into the Vines and Ovines research program.
The project’s specific objectives are to:
1. Convene a two-day short course to educate and train sheep producers and vineyard managers on the principles of ruminant grazing behavior and techniques to modify grazing behavior.
2. Establish at least five vineyard grazing demonstration sites utilizing sheep with a trained aversion to grape leaves for vineyard floor management during the 2009 growing season.
3. Assist demonstration site producers to apply appropriate grazing practices and monitor the grazing impacts on the vineyard.
4. Develop a set of measurements that the producers can use to evaluate the success of the practices used for training the sheep and for grazing the vineyard floor.
5. Hold at least three field days to demonstrate and extend the practice of using trained sheep for vineyard floor management to sheep producers and vineyard managers.
6. Convene a meeting with all project participants in July 2009 to exchange and record information on the successes, problems and solutions of using trained sheep for vineyard floor management.