Vineyard floor management relies on herbicides, especially glyphosate. This practice,
once deemed sustainable and safe, is now jeopardized by glyphosate-resistant weeds and has
come under public scrutiny. Mechanical under-vine cultivators are an option available to grape
growers; many types of equipment are commercially available. However, its adoption lags
behind the more familiar herbicide use. Under-vine cultivators’ performance, costs and applications have not been
well-researched. Limited information on reliable providers further hinders adoption of undervine
cultivators. This project proposes:
- to conduct on-farm trials to evaluate different undervine
cultivators types alone or in combinations as compared to herbicide application;
- with grower-collaborator participation, to compare the economics of under-vine cultivation to
herbicide application and record operational information to estimate reliability, operation
capacity, and scheduling of cultivation operation during the growing season;
- to compile a list of all equipment commercially available and a list of vendors located in the Western
Region, and to document growers’ perceptions and experiences with under-vine cultivators. This
will allow us to generate specific information about operational costs, performance, the window
of operation, applications, and limitations.
- Evaluate the weed control performance of three under-vine cultivators (hoe blade,
rotary tiller, and rotary brush) used alone or in combination. Monitor undesirable trends in soil structure
using field penetrometer and soil-water content using a portable soil moisture sensor.
- Compare under-vine cultivation equipment to herbicide application and record
operational information to estimate reliability, operation capacity, and scheduling of
cultivation operation during the growing season. Grower-collaborators will be actively
engaged in this objective, and their input will become the basis for the emphases of
outreach events and materials.
- Compile a list of cultivators available in the market with estimated costs, operational
capacity, tractor requirement, applications and limitations and develop extension
materials and presentations to promote adoption of this technology.
Field experiments will be conducted in commercial vineyards in Oregon located in the Willamette Valley and in the Umpqua Valley. The weed control treatments are:
- hoeing blade,
- rotary tiller,
- brush-weeder plus hoeing blade,
- brush-weeder plus rotary tiller,
- hoeing blade plus rotary tiller,
- brush-weeder plus hoeing blade plus rotary tiller,
- herbicide glyphosate,
- untreated control.
Treatments will be performed by an under-vine cultivator manufactured by ID-David. This equipment can accommodate all three cultivator types in a single pass, making it a more cost-effective option for growers. Treatment plots will be arranged in randomized block design with four replicates, which will allow the evaluation of each cultivator individually or in all combinations.
Assessments will be performed 15 and 30 days after each treatment. Weed control will be scored visually using the scale 0% for no control to 100% for complete weed control. Additionally, weed growth will be monitored non-destructively using digital image analysis. Weed density and biomass will be estimated at the end of the experimental season. A comparative cost analysis for each treatment will be made including time to accomplish each treatment.
Soil compaction will be monitored using a soil penetrometer to depths of 15 and 36 inches, once per year while soil is at field capacity in late winter-early spring. Ten sites per plot will be sampled.
Soil water content will be monitored using a portable moisture probe (Field Scout TDR Soil Moisture or equivalent). Ten measurements per plot will be performed before cultivation. Soil moisture will be monitored during the season as well.
The cost analysis of the cultivator operation or herbicide application will be calculated on a per-acre basis by recording the cost of equipment, labor, fuel, lubrication, repairs and maintenance, materials, herbicide, and sprayer using formulas proposed by the American Society of Agricultural and Biological Engineers. Collaborating growers working with the cultivator will record operation speed (mph), operation efficiency (hours/acre), working days (days for which field operation is possible – precipitation, inadequate soil moisture, equipment reliability, down days due to maintenance, field slope, soil type, and planting density. This information will allow growers to estimate equipment compatibility with their fields, equipment requirements, and scheduling of activities. These factors will become part of the basis for management practice recommendations. Cultivators that minimally disturb soil may have an extended window of operation over those that cause greater soil disturbance.
To address the lack of information related to under-vine cultivators, we have compiled a draft document listing all equipment commercially available and vendors located in the Western Region. Only equipment with US-based technical support will be included in the list. This list will be available online and will be disseminated during extension meetings.
Educational & Outreach Activities
In 2019, two field days were organized in collaboration with other researchers and local industry to present the recent updates on under vine weed control.
The first field day was held in May 17, 2019 in Medford Oregon. Speakers included Dr. Marcelo Moretti, presenting the research funded by W-SARE and Mr. John Roncoronni, a University of California Cooperative Extension Weed Specialist based in the Napa Valley. Mr Roncorroni shared his experiences of weed control without herbicides. Additionally, a local vineyard consultant, Mr. Joey Myeres of A to Z Wineworks, shared his experiences and recommendations for under-vine cultivation. In the final part of the workshop, two implement manufactures, Clemens and Agrofer, demonstrated some of their implements. Over 25 local growers attended the workshop.
The second field day was organized in collaboration with Low Input Viticulture and Enology (LIVE) and held in Salem, OR in August 2019. A total of 30 growers joined the workshop to learn about the results of the under vine cultivation project.
In addition to the workshops, Dr. Moretti was invited to present interim project results to the Eola-Amity Hills sub-AVA Association (EAHWA), an Oregon winegrower association (November 2019), and to the California Society of Weed Science (Jan 2020) in Monterey, CA.
Cultivation timing relative to soil moisture content
Soil disturbance, disaggregation, compaction
This project is on-going, so outcome assessment would be premature at this point. However, the initial results demonstrate that growers are interested in changing their floor management practices. The workshops were well received and the in-field demonstration especially so. Growers that attended the meeting engaged in conversation with manufacturers and among themselves and indicated that under-vine cultivation was one of their top priorities for the following seasons.
The challenge with under-vine weed control studies is the large up-front cost associated with the study. It was necessary to purchase a tractor, the implement, a trailer for transportation, and access to larger trucks (3/4 ton) to deliver the implement to the field sites.
A second challenge is that only a few implements are tested at a time because of the extensive time needed to set-up the different implements between treatments. In general, we would spend 1.5 h or more in preparing the implement before conducting the work.
Finally, in-field equipment repairs created another set of unforeseen delays. The equipment sat idle during peak season as we waited for parts. Despite technical difficulties, we successfully conducted field studies and will continue in 2020.
In the methods for Objective 2, we proposed to let growers work with the implement during the season and collect data on operational speed, capacity, and other experiences that they may have wanted to share. Although the growers that participated in that objective enjoyed the opportunity to work with different implements, it limited our ability to conduct further research; the optimum window for weed control in vineyards can be restricted by soil moisture or rainfall. Further, we could only gather a few data grower experience data points because only one piece of equipment was available. In future studies, a survey of growers who currently own under vine implements might be a better approach to collect a larger data set and better calculate costs.