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Weed control is a significant cost for speciality crop producers, especially on organic farms. Agricultural operations are still largely dependent on hand weeding that is labour intensive and labour shortages and rising wages have led to a surge in food production costs. Thus, there is an inherent need to automate weed control and contain both labour costs and demands. Automatically distinguishing weeds from the crop plant is a complex problem since weeds come in a wide variety of colours, shapes, and sizes, and crop plant foliage is often overlapped with itself or occluded by the weeds. Current technology in commercial use, cannot reliably and effectively perform the differentiation task in such complex scenarios in real-time. As a solution to this problem, our team at the University of California, Davis has developed a novel concept called crop signalling, a technology to make crop plants machine readable and reliably distinguishable from weeds for automatic weed control. Four different techniques have been investigated and developed to make smart crop marking systems such as a) systemic markers, b) fluorescent proteins, c) plant labels and d) topical markers. Indoor experiments have been conducted for each method. Field experiments, using plant labels and the topical markers methods, have been successfully conducted for real-time weed control in tomato and lettuce. The results demonstrated that robots could automatically detect and distinguish 99.7% of the crop plants with no false positive errors in dense complex outdoor scenes with high weed densities. The crop/weed differentiation was thus effective, fast, reliable, and commercialisation of robotic weed control using the technique may be feasible.

A commercial intrarow rotating cultivator was tested for weed removal and impact on hand-weeding times in bok choy, celery, lettuce, and radicchio. The rotating cultivator was tested as an automated crop thinner and weeder in direct-seeded bok choy and lettuce as an alternative to hand-thinning and -weeding. The rotating cultivator utilized machine-vision guidance to align a rotating disk with the crop plant to be saved and to remove weeds and undesired crop plants. The rotating cultivator was compared to a standard interrow cultivator, which could not remove weeds from the plant line. Main plots were cultivator type, rotating, or standard, and subplots were herbicides: pronamide for lettuce or prometryn for celery. Weed densities, hand-weeding times, crop stand, and yields were monitored. Economic analysis was performed on a subset of the data. The intrarow rotating cultivator was generally more effective than the standard interrow cultivator for reducing weed densities and hand-weeding times. However, the rotating cultivator reduced seeded lettuce stands by 22 to 28% when compared to hand-thinning and standard cultivation, resulting in lower yields and net returns. In transplanted celery, lettuce, and radicchio, the rotating cultivator removed more weeds than the standard cultivator, and reduced stands by just 6 to 9% when compared to the standard cultivator. In transplanted lettuce, the rotating cultivator was more precise and did less damage to the crop. Because transplanted crops were larger than the weeds, they were more easily differentiated using this technology. Net returns were therefore similar between the two cultivators. What is needed for celery and leafy vegetables is an effective intrarow weed removal system that reduces or eliminates the need for hand-weeding yet does not reduce yields. The rotating cultivator was developed for transplanted crops, where it performs adequately, but it cannot be recommended in the seeded crops evaluated.

Machine-vision cultivator guidance systems are commercially available to growers, but little work has been done to determine if these guidance systems can improve integrated weed management systems in vegetable crops. Studies were conducted in 2005 and 2006 in broccoli and lettuce to evaluate band-applied DCPA or pronamide, respectively, and four noncultivated bands ranging from 5.1 to 12.7 cm. DCPA or pronamide were applied in bands centered on the seed line at 0, 7.6 or 12.7 cm wide. A commercial machine-vision system was used to guide a commercial cultivator. Generally, weed densities and hand-weeding times were less where the DCPA band in broccoli or the pronamide band in lettuce were 7.6 or 12.7 cm wide compared to no herbicide. Weed densities were lowest in both crops where the noncultivated band width was 5.1 cm compared to 12.7-cm noncultivated bands. For broccoli in both 2005 and 2006, net returns above production costs were generally higher in the 7.6- and 12.7-cm-wide DCPA bands compared with the no-herbicide band. In lettuce in both years, the no-pronamide treatment had higher net returns, when compared with the 7.6- and 12.7-cm pronamide bands. Lettuce yields and higher net returns in the no-pronamide treatment compared to the 7.6- and 12.7-cm pronamide bands may be due to slight yield reduction from pronamide. Results suggest that pronamide was not needed during the dry months of the year when weed management tools such as hand-weeding and cultivation work very well. However, in periods of rainy weather when cultivation and hand-weeding are not possible, then pronamide would likely provide the greatest economic benefit. Given the large impact of cultivation on vegetable weed management programs, the greatest potential benefit of machine-vision guided cultivators is if they facilitate more timely and effective cultivation.

This paper examines differences in the management styles of a purposive sample of almond and winegrape growers in California’s Central Valley, including participants and non-participants in biologically integrated farming systems programs. Using Q methodology, we elicited rankings of economic and social values and goals as they relate to farm production, environmental stewardship, family and community, and leisure. These rankings led to three distinct management styles, labeled as Environmental Stewards, Production Maximizers, and Networking Entrepreneurs. The results demonstrate that farmers make decisions following diverse management strategies and suggest that outreach programs aimed at advancing biologically based farming practices must address these differences to be most effective.

While questions about the environmental sustainability of contemporary farming practices and the socioeconomic viability of rural communities are attracting increasing attention throughout the US, these two issues are rarely considered together. This paper explores the current and potential connections between these two aspects of sustainability, using data on community members’ and farmers’ views of agricultural issues in California’s Central Valley. These views were collected from a series of individual and group interviews with biologically oriented and conventional farmers as well as community stakeholders. Local marketing, farmland preservation, and perceptions of sustainable agriculture comprised the primary topics of discussion. The mixed results indicate that, while many farmers and community members have a strong interest in these topics, sustainable community development and the use of sustainable farming practices are seldom explicitly linked. On the other hand, many separate efforts around the Valley to increase local marketing and agritourism, improve public education about agriculture, and organize grassroots farmland preservation initiatives were documented. We conclude that linking these efforts more explicitly to sustainable agriculture and promoting more engagement between ecologically oriented farmers and their communities could engender more economic and political support for these farmers, helping them and their communities to achieve greater sustainability in the long run.

We consider the adoption of biologically integrated agricultural practices from the perspective of farm management style. Adoption decisions for farming practices must fit into a broader farm decision-making context that incorporates economic, environmental, social, family and personal considerations, as well as use of agricultural information sources. Drawing from a study of California almond and winegrape growers, we demonstrate that management styles differ substantially among farmers, these differences affect use of information sources and adoption of biologically based practices on the farm, and such adoption does not negatively affect crop performance. We used Q-methodology, a method for eliciting qualitative data using a variant of factor analysis, to identify three distinct management styles among a purposive sample of 40 growers. The Environmental Stewards' management style places higher priority on conservation of natural resources than on getting the highest possible yields or profits. Production Maximizers, with a different style, prioritize more traditional goals of producing the highest possible yields and quality and focusing resources on the farm rather than on outside concerns. Networking Entrepreneurs, on the other hand, value learning about innovative techniques in social contexts such as informational field days, evaluate new information with a business-like attitude and enjoy off-farm interests. A two-season mail survey of farming practices and information sources demonstrated that differences in management styles affect the adoption of practices. Environmental Stewards were more likely to practice biological pest control and encourage wildlife and less likely to use the most toxic chemicals. Production Maximizers had a greater tendency to use prophylactic and broad-spectrum chemicals, while Networking Entrepreneurs preferred more innovative biological pest controls but tended to avoid time-consuming cultural practices. Production Maximizers were distinguished by less use of more social forms of communication, such as attending field days and talking with other growers. Crop health and quality indicators showed that almost all growers were managing their crops very successfully, regardless of management style or choice of practices. These results hold important implications for efforts to increase the adoption of sustainable agriculture, especially by showing that contents and methods of outreach efforts must vary to accommodate diverse farm management styles.

The beginnings of modern organic agriculture are generally attributed to the writings in the 1940s of Sir Albert Howard and Lady Eve Balfour, which espoused that the health of plants, soil, livestock, and people are interrelated. It followed that farming practices should work in harmony with nature using inputs produced on farm. Organic agriculture was popularized in the United States by J.I. Rodale through the magazine Organic Farming and Gardening. Rodale advocated an approach to farming based on understanding and working with natural systems rather than attempting to control them. In the late 1940s and into the 1950s, chemical intensive agriculture successfully boosted agricultural productivity at relatively low cost, thus diverting attention away from the organic movement. However, the publication in 1962 of Rachel Carlson's Silent Spring gave rise to environmental consciousness and a renewed focus on

The Lodi-Woodbridge Winegrape Commission Crush District 11 was created by referendum during the summer of 1991. The commission conducts extensive on-farm research trials and demonstration projects in cooperation with the University of California, the California State University system and local growers. The results have been disseminated through a series of regular grower meetings, seminars and an IPM newsletter sponsored by the commission and widespread coverage in the agriculture and general media. Several pest management practices which could reduce pesticide inputs have been promoted by the commission's IPM Program, and others are being further validated or are being researched for applicability to growers in the area. The research falls into two distinct categories. The first category of research is evaluation of the efficacy of recommended practices and includes economic analysis and the collection of biological data to evaluate performance from the perspectives of vineyard ecology, input use, and profitability. Intensive study of 10 growers over 2 years showed a highly variable level of adoption. The yield response to pest control inputs showed increasing returns up to the level of inputs of $375 per hectare after which returns leveled off. The second category of research is the development of alternative practices through on-farm controlled trials. The results of 3 on-farm trials are reported. A cover crop trial showed a reduction of pests in 1995 but no difference in 1994 between the cover cropped and bare soil blocks. Yellow sticky bands significantly reduced the number of leafhoppers in a trial vineyard, but was not as effective as pesticide treatments. The comparison of four alternative weed management techniques demonstrated that the use of an in-row cultivator is more effective than preemergent herbicides or mulch placed along the vine row in controlling weeds. A visual sprayer was shown to reduce the use of contact herbicide. The on-farm approach to all of the research and the ‘in your own backyard’ nature of the meetings has created the sense of ownership for the growers that has been instrumental in achieving grower support. The public nature of the information provided by the commission and grower members to all winegrape producers implies a recognition among members of their interdependence and the long-term benefits of reducing pesticide use as a group. The recognition of interdependency is crucial for any group trying to form an IPM district.