Laura Tourte

Organic Agricultural Production in the United States: Debates and Directions

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 Carlsons Silent Spring gave rise to environmental consciousness and a renewed focus on

Evaluation and Economics of a Machine-Vision Guided Cultivation Program in Broccoli and Lettuce

Abstract 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. Nomenclature: DCPA; pronamide; broccoli, Brassica oleracea L. var. botrytus L. ‘Marathon’; lettuce, Lactuca sativa L. ‘Sniper’, ‘PIC 714’, and ‘Darkland’

Evaluation and Economics of a Rotating Cultivator in Bok Choy, Celery, Lettuce, and Radicchio

Abstract 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. Nomenclature: Prometryn; pronamide; bok choy; Brassica rapa L. subsp. chinensis; celery; Apium graveolens L. var. dulce (Mill.) Pers.; lettuce; Latuca sativa L.; radicchio; Cichorium intybus L. Resumen Se evaluó el uso de un cultivador comercial rotativo intra-línea para la eliminación de malezas y su impacto en la deshierba manual en bok choy, apio, lechuga y radicchio. El cultivador rotativo fue evaluado para ralear el cultivo y para deshierbar automáticamente en bok choy y lechuga de siembra directa como alternativa al raleo y a la deshierba manual. El cultivador rotativo fue guiado con una máquina de visión para alinear un disco rotativo con la planta del cultivo que debía ser salvada y para remover las malezas y las plantas del cultivo no deseadas. El cultivador rotativo fue comparado con un cultivador inter-línea estándar, el cual no podía remover malezas de la línea de siembra. Las parcelas principales fueron el tipo de cultivador, rotativo o estándar, y las sub-parcelas fueron herbicidas: pronamide para la lechuga o prometryn para el apio. Se determinó las densidades de malezas, los tiempos de deshierba manual, y los rendimientos. Se realizó un análisis económico en un subgrupo de los datos. El cultivador rotativo intra-línea fue generalmente más efectivo que el cultivador inter-línea estándar para reducir las densidades de malezas y los tiempos de deshierba manual. Sin embargo, el cultivador rotativo redujo el número de plantas de lechuga establecidas en siembra directa en 22 a 28% en comparación con el raleo manual y el cultivador estándar, lo que resultó en menores rendimientos e ingresos netos. En apio, lechuga y radicchio de trasplante, el cultivador rotativo removió más malezas que el cultivador estándar, y redujo el número de plantas establecidas en solamente 6 a 9% cuando se comparó con el cultivador estándar. En la lechuga de trasplante el cultivador rotativo fue más preciso y causó menos daño al cultivo. Los cultivos trasplantados fueron más fácilmente diferenciados usando esta tecnología porque fueron más grandes que las malezas. Los ingresos netos fueron de esta forma, similares entre los cultivadores. Lo que se necesita para el apio, y los vegetales de hoja es un sistema efectivo para la remoción de malezas intra-línea que reduzca o elimine la necesidad de deshierba manual sin reducir los rendimientos. El cultivador rotativo fue desarrollado para cultivos de trasplante, en los cuales se desempeña adecuadamente, pero este no puede ser recomendado para cultivos de siembra directa.

Foliar-applied seaweed and fish powder do not improve yield and fruit quality of organically grown processing tomatoes

ABSTRACT In a replicated field plot study conducted during 1994 and 1995 in the Sacramento Valley, California, U.S.A., combinations of three levels each of soil-applied organic fertilizing materials and foliar-applied seaweed and fish powder were tested on processing tomato (Lycopersicon esculentum Mill.), cv. Orsettis Halley 3155 to determine effects on crop yield, fruit quality and economics. The experimental design was a factorial split plot arranged in a randomized complete block with four replicates. Main plot treatments consisted of three soil fertility levels: (1) control, (2) woolypod vetch (Vicia villosa Roth ssp. varia [Host] Corbiere), cv. Lana and (3) Lana vetch and poultry manure compost. Subplot treatments consisted of three foliar spray levels: (1) control, (2) seaweed and fish powder applied at label rate, and (3) seaweed and fish powder applied at twice the label rate. The study was designed to simulate practices used by growers of organic processing tomatoes in the area. No significant differences were found for yield or quality of marketable fruit in any soil and foliar treatment combination in either year. Because no significant differences for yield or fruit quality were detected, no economic benefit for seaweed and fish powder can be inferred under the experimental conditions.

The Lodi-Woodbridge Winegrape Commission: a Framework for Implementing IPM

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 commissions 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

Farmer goals and management styles: Implications for advancing biologically based agriculture

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.