Walnut BIFS project: San Joaquin County walnut growers survey
Farmers attend BIFS walnut field day in San Joaquin County (photo by Joe Grant)
The walnut Biologically Integrated Orchard Systems (BIOS) project was initiated in 1998 by a group of walnut growers who approached UC Cooperative Extension San Joaquin County farm advisor Joe Grant to develop a pilot study on growing walnuts with fewer pesticides. In January 1999 this project received a three-year grant from SAREP's Biologically Integrated Farming Systems (BIFS) program. With BIFS funding, Grant worked with 12 enrolled growers to implement and demonstrate an integrated approach to walnut farming that seeks to reduce pesticide use and improve yield and quality through soil building, intensive field monitoring, biological control, and beneficial insect habitat enhancement to control pests. Each enrolled "BIOS grower" established a BIOS block to demonstrate practices such as pheromone mating disruption to control codling moth, nitrogen budgeting, replacing pre-emergence with post-emergence herbicides, and growing cover crops. Project results show that enrolled growers were able to produce high quality walnuts while reducing pesticide and fertilizer use.1 Working with Grant, the Community Alliance with Family Farmers (CAFF) coordinated project outreach efforts to extend this information to other walnut growers in the region.
As the project was concluding in the fall of 2001, SAREP worked with Grant, David Ramos of the Walnut Marketing Board, and a consulting firm, Harder & Co. Community Research, to survey all San Joaquin County walnut growers. The results of this survey provide an overview of farming practices and attitudes of county walnut growers three years after the establishment of the walnut BIOS project. The U.S. Environmental Protection Agency Region 9 Agriculture Initiative provided funding for this study.
Methods
A nine-page questionnaire was developed that asked growers or their farm managers questions about farming practices they used in 2001, information sources, attitudes, exposure to the walnut BIOS project, and background information on the grower and his/her farming operation. After the questionnaire was pre-tested by local walnut growers, it was sent to all 722 walnut growers on a list provided by the San Joaquin County Agricultural Commissioner's office. Growers received the questionnaires in early January 2002. By February, 322 completed questionnaires were received, representing a 51% response rate after deleting growers from the original list who reported not growing walnuts in 2001.
Brief telephone interviews with 24 randomly selected non-respondents showed that non-respondents were not statistically different from the 322 respondents in their age or answers to all seven questions on crop practices. However, the non-respondents did tend to have significantly fewer walnut acres than the respondents, indicating that growers with fewer walnut acres may have been less likely to participate in this survey than growers with larger walnut acreage.
Results and Discussion
Survey respondents
A comparison of survey respondents to official county walnut acreage
figures2
confirms that the sample of respondents over-represented growers with
larger walnut acreage. The survey sample included fewer than 30% of county
walnut growers with five or less walnut acres, yet it included over 80%
of county walnut growers with more than 200 walnut acres (Table 1). Survey
respondents reported that they farm a total of 21,245 acres of bearing
walnuts, which was 74% of the 28,838 total bearing walnut acreage in the
county in 2001.
Orchard Floor Management and Fertility Practices
Reducing supplemental nitrogen applications to levels more consistent with actual demand would save growers money and reduce the potential for leaching and groundwater degradation. BIOS growers were able to use less nitrogen fertilizer yet maintain good soil fertility by using leaf tissue analysis to monitor nitrogen status, and calculating a "nitrogen budget" to estimate fertilizer needs. Almost 40% of respondents said that they used the concept of nitrogen budgeting to estimate fertilizer needs (Table 2). Other alternative practices, such as chipping or shredding orchard prunings in field and the use of compost or manure for fertilizer, were used by a small percentage of growers (17% and 8% respectively).
Cover crops have been shown to improve soil structure, fertility, and water penetration in addition to other benefits. The use of cover crops was demonstrated as an important part of the BIOS system. Cover crops (either new planting or self-reseeded) were used by 21% of respondents. These respondents were asked about the specific benefits and challenges of using cover crops (Table 3); a majority of these growers felt they had observed increased water penetration and dust reduction. In general, drawbacks of using cover crops were observed by smaller percentages of these growers; however, over a third of these growers felt they had observed an increase in gophers, an increase in water use, and trash at harvest.
The use of pre-emergence herbicides to control weeds is a common practice of walnut growers—63% of respondents reported using it (Table 2). Since walnuts are harvested from the orchard floor, orchard floor management is an important component of the farming system. BIOS growers were encouraged to replace pre-emergence with post-emergence herbicides (such as RoundUp), apply herbicide treatments in a narrower strip, and use spot treatments to control weeds as necessary. Over a third of respondents (36%) reported that they used spot treating only around trees.
Insect and Mite Management Practices
BIOS growers managed codling moth, the key insect pest for walnut growers, by experimenting with the use of pheromone mating disruption and reduced risk pesticides. Frequent monitoring for pests and beneficial insects and the enhancement of beneficials were also key components of the walnut BIOS project.
Organophosphate insecticide sprays to control codling moth were used by 67% of respondents (Table 4). Only 18 respondents (6%) used mating disruption in 2001; 11 of these were BIOS growers. Clearly, the use of pheromone mating disruption as an alternative method to control codling moth in walnuts is in its infancy. Although 80% of respondents reported that they had heard of using mating disruption to control codling moth in walnuts, only 32% reported knowing how to use it.
Survey results confirmed that BIOS growers found that mating disruption works: 100% of BIOS growers agreed with the statement: "The use of mating disruption is effective to control codling moth." However, 70% of all other respondents responded "Don't know" to this statement, pointing to the importance of, and opportunities for, future outreach efforts to inform walnut growers about the effectiveness of pheromone mating disruption in walnuts.
In 2001, cost was still an important issue in the use of mating disruption. Over half of the BIOS growers disagreed with the statement: "Use of mating disruption is cost effective." New products (such as a sprayable formulation of mating disruption pheromones) are becoming available that may improve the economic feasibility of using mating disruption to control codling moth in walnuts.
BIOS growers were encouraged to implement habitat restoration and enhancement practices including setting up owl or bat nesting boxes and insectary plantings along farm borders or waste areas. Although 21% of respondents report using owl boxes or bat houses, only 2% have insectary hedgerow plantings to attract beneficials. Space limitations and a general lack of perceived potential benefits of insectary plantings may limit growers' interest in planting insectary hedgerows.
The majority of respondents understand the value of beneficial insects—78% agreed (either strongly or somewhat) with the statement "Increasing the population of natural enemies/beneficials in or near a walnut orchard can help manage pests." Only 3% disagreed with this statement; 19% responded "Don't Know."
Attitudes
Growers were asked their level of agreement with several statements in the survey questionnaire. Fifty-seven percent of respondents agreed (either strongly or somewhat) that "It's worth using practices that reduce my overall chemical and fertilizer use even when it might take a little more time or expense" showing that a majority of growers are willing to go to some effort or cost to reduce their agricultural chemical use. Sixty-four percent of respondents reported they did try to reduce their use of pesticides during the 2001 walnut-growing season. As might be expected, 71% of these respondents reported that "cost" was the most important reason for their efforts to reduce the use of pesticides. Environmental concerns, health concerns, and protecting beneficial insects were also frequently mentioned as one of, if not the most important, reason to reduce pesticide use.
Forty-six percent of respondents reported they were interested in experimenting with new management practices. BIFS projects provide the funding for many growers to experiment and demonstrate the use of alternative practices and then, through organized field days and other events, show what they have learned to other growers.
Project Outreach and Key Sources of Information
A key element of the walnut BIOS project was outreach to other walnut growers in the region. Survey results show that almost half of the survey respondents were exposed to the project in some way. Twelve respondents (4%) were enrolled as BIOS growers in the project. Excluding these BIOS growers, 53% of survey respondents reported that they had "heard of the walnut BIOS program"; 39% had read the walnut BIOS newsletter; 21% had talked with a BIOS grower or project management team member; and 15% had attended at least one walnut BIOS field day.
Respondents were asked to identify the three most important sources of information from a list of 19 different choices. Pest control advisers (PCAs) were most often identified as one of the three most important information sources (53%). This highlights the importance of the involvement of PCAs in BIFS projects. "Results of monitoring/inspecting orchard" was identified as one of the three most important information sources by 38% of respondents. Many BIFS projects support intensive monitoring, recognizing the information intensive nature of biologically integrated farming. And finally, "other walnut farmers" were identified by 32% of respondents as one of the three most important information sources. Results from a similar survey of Lodi-Woodbridge winegrape growers, conducted at the conclusion of a three-year BIFS project, also found that PCAs and other growers were most often identified as important information sources.3 BIFS projects frequently provide many opportunities for growers to share their experience with other growers as well as researchers.
Research Topics
Respondents were asked to list the top three walnut-related issues they would like researchers to focus on (Figure 1). Since this was an open-ended question, many respondents offered general topics such as "pest control" and "diseases," while others identified more specific topics. The disease Blackline was the research topic identified most frequently as a high priority. (Column totals add up to more than 211 because respondents could identify up to three research topics.)
Conclusion
In addition to serving as baseline data for future studies, the results of this survey help to identify opportunities for further extension efforts geared toward enhancing and extending the impact of the walnut BIOS project. In summary, these results indicate that of the walnut growers who participated in this survey, the majority:
- want to reduce their chemical and fertilizer use
- are primarily motivated to reduce ag chemical use by the desire to save money
- are also motivated by concerns for health and the environment
- highly value pest control advisers and the results of monitoring/inspecting the orchard as important sources of information for farm management decisions
- do not know that mating disruption can be effective to control codling moth and do not know how to use it
- are not using BIOS practices that may help them to reduce their ag chemical
use, including:
- nitrogen budgeting to more accurately estimate fertilizer needs
- replacing pre-emergence herbicides with other strategies such as spot treating and narrow strip spraying of post-emergence herbicides
- establishing cover crops
- using pheromone mating disruption
Further dissemination of the information learned in this project will
take place as part of a California Department of Food and Agriculture
"Buy California Initiative" grant project that will begin in
January 2003 (see article on page 1). Other current extramurally funded
education and outreach programs for California walnut growers include
the Stanislaus County BIOS program led by the Community Alliance with
Family Farmers, the Pest Management Alliance Workplan for California Walnuts
funded by the California Department of Pesticide Regulation, and the California
Walnut IPM Expansion Project led by the Center for Agricultural Partnerships.
It is likely that there will be further adoption of the alternative practices
demonstrated in the walnut BIOS project. SAREP hopes
to conduct a follow-up to this survey in order to measure these potential
changes in practices.
SAREP is currently working on a full report of survey results. For more information, contact Bev Ransom at baransom@ucdavis.edu.
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