U.S.EPA
Methyl Bromide Alternative Case Study
Part of EPA 430-R-96-021, 10 Case Studies, Volume 2
December 1996

Organic Strawberry Production As An Alternative to Methyl Bromide

Organic strawberry production is an effective integrated approach that offers an alternative to methyl bromide use for California strawberries. Organic producers do not use methyl bromide or any other synthetic pesticide or fertilizer in the production of certified organic strawberries (MBRTF 1995). Instead they use organically acceptable production methods to control or suppress weeds, plant pathogens, and nematodes including the use of plastic mulches coupled with supplemental hand weeding to suppress weeds, release of mass-reared beneficial insects, soil solarization, good sanitation practices, resistant cultivars, biological control fungi and/or organic matter, hot water treatments, crop rotation, various cultural controls, and irrigation management practices (Liebman 1994, University of California 1993, Liebhardt et al. 1989). These techniques are part of an overall integrated pest management (IPM) program.

There are several advantages to converting conventional, high-input strawberry production systems to organic systems, including elimination of synthetic fertilizers and pesticides and the building of healthy soil. Recent improvements in organic strawberry production have resulted in yields as high as 89 percent of that obtained from conventional strawberry production. Furthermore, organically grown strawberries can be sold at a higher price than conventional strawberries, thus offsetting any yield reductions (Cochran 1995). While only a small percentage of the California strawberry crop is produced organically, price premiums of as much as 50 to 100 percent for certified organic strawberries provide a considerable incentive for growers to consider organic production techniques in the future (Gliessman et al. 1994). Organic strawberry production also eliminates environmental stress caused by pesticide use, thus increasing soil biotic diversity and beneficial organisms (i.e., a complex of natural predators and parasites) (Liebman 1994, Baker 1996).

Despite the advantages of organic production as an alternative to methyl bromide, it is unlikely that all strawberry farms will switch to organic production. If all large growers did shift to organic production practices, the price differential between conventional vs. organic strawberries would decrease along with some of the price incentives to convert to organic production practices (Baker 1996, Cochran 1996). Instead, without methyl bromide, most conventional (non-organic) California strawberry producers probably would be able to use a variety of other pesticides to help improve yields over those obtained under organic systems alone. For example, the use of chloropicrin, and other synthetic chemical treatments applied in addition to the "organic" approaches discussed here can further improve yields (Gliessman et al. 1996).

California Fresh Market Strawberries

California strawberry growers produce 75 percent of the fresh market strawberries and 80 percent of the processed strawberries in the United States (Welch 1989) on only about 19,250 acres of land (mainly in Central Coastal counties in California) (Gliessman et al. 1996, Larson and Shaw 1994). Strawberry production in California typically occurs all year long (Welch 1989) with yields steadily increasing over time for the last four decades, making it one of the most valuable and stable crops in the state (Wilhelm and Paulus 1980). However, strawberries are also one of the most expensive/labor intensive crops to grow (Gliessman et al. 1990 and 1996, Webb 1994, and Cochran 1995). Although strawberries are a perennial crop, commercial growers in California treat them as annuals, planting new transplants from nurseries in the Sierra foothills each year (Liebman 1994). Californian farmers routinely obtain superior yields over producers in other states (i.e., Oregon, Florida, Louisiana, and North Carolina). For example, California strawberry production yields average 24 tons per acre, with some growers obtaining between 35 to 40 tons per acre, several times higher than that achieved in other states (Wilhelm and Paulus 1980).

The loss of methyl bromide will also have an impact on strawberry nurseries. Because California strawberries are grown as annuals, nurseries must grow transplants for the entire crop each year. In the past, methyl bromide has been the key to producing clean planting stocks. However, without methyl bromide, careful monitoring for pests, vigilant sanitation efforts, and the use of other soil disinfestation techniques (i.e., steam and biocontrol inoculants) will be needed in the future. In addition, it may be necessary to grow plants in bags of sterilized peat or rock wool, similar to that used for strawberry production in The Netherlands and for other nursery crops in the U.S. (Liebman 1994).

Overview of Methyl Bromide Use in Conventional California Strawberry Production

Methyl bromide has been used extensively as a preplant fumigant in California strawberry production and is one of the keys to the stability and economic viability of the California strawberry market (Wilhelm and Paulus 1980). In 1992, about 85 percent of the state's crop was planted on land that was fumigated with a total of 4.5 million pounds of methyl bromide (USDA 1993), representing approximately 25 percent of all methyl bromide applied in California and about 10 percent of the total annual domestic use of methyl bromide (Liebman 1994). The only strawberry land that is not fumigated are those plots certified for organic production (less than 100 acres in the state) or crops left in the ground for a second year (10-20 percent of California's strawberry acreage) (Westerlund 1994, Liebman 1994).

In conventional California strawberry production, growers fumigate land to be planted to strawberries with a mixture of methyl bromide and chloropicrin (2:1 ratio) for the control of most plant pathogens, nematodes, and weeds (Braun and Supkoff 1994, Welch et al. 1985). Because of the need for specialized application equipment and concerns for worker safety, methyl bromide can only be applied by licensed applicators (University of California 1993). Application rates range from 300 to 400 pounds per acre with associated treatment costs of approximately $1,200 to $1,400 per acre (Liebman 1994). The frequency of fumigation is determined by the rotation sequence practiced by the grower. Some growers, especially in Southern California, plant strawberries each year and fumigate before each crop is planted. On the Central Coast near Watsonville, growers often rotate crops (i.e., bellbean, barley, lettuce, broccoli, cauliflower, or celery) and fumigate alternating years (Westerlund 1994 & 1996, Liebman 1994).

Organic Production Techniques as a Replacement for Methyl Bromide

Twenty-two of the 600 strawberry farms in California are certified as organic according to The California Certified Organic Farmers Directory. Unlike conventional strawberry farmers, organic farmers use a rotation of 1 to 2 berry crops every 4 to 5 years and do not use methyl bromide or any other synthetic pesticides or fertilizers (Gliessman et al. 1990, Cochran 1995, Webb 1994). An example of successful organic strawberry production is Swanton Berry Farms in the central coastal area of California, which has profitably grown strawberries without synthetic inputs (including methyl bromide) since 1986 (Cochran 1995). Weeds, soilborne pests, and diseases are controlled or suppressed using a combination of organically acceptable methods, including crop rotation and cover crops, plastic mulch, compost, cultural controls, and careful management of naturally occurring beneficial predators with supplementary releases of mass-reared beneficials when needed (Gliessman et al. 1996, Cochran 1995).

Costs Associated with Organic Strawberry Production

Limited research has been conducted on organic strawberry production costs and techniques and the conversion from conventional strawberry production to organic production in California (Gliessman et al., 1994, Liebman 1994). In one three-year university sponsored, on-farm research trial conducted at Swanton Berry Farms, University of California researchers initially achieved strawberry yields that were 68 percent of strawberries produced with conventional chemicals (Gliessman et al. 1994). While yields were lower for organically produced strawberries, they steadily improved over the study period from 2,068 trays per acre in the first year, to 2,388 trays per acre (79 percent) in the third year. Specifically, organic yields relative to those of conventional strawberries were 39 percent lower in the first year, 30 percent in the second year, and 28 percent in the third year (Gliessman et al. 1996). Similar studies on conversion to organic production of strawberries and other crops support these findings -- i.e. that yields increase over time (Sances and Ingham 1995, Liebhardt et al. 1989). More recently, Swanton Berry Farms has been able to achieve yields as high as 3,100 trays per acre, a 13 percent improvement over yields attained in the previous 3 year study and 89 percent of the yield using conventional techniques (Cochran 1995). However, when comparing these yields to those of conventional strawberry growers, it must be noted that the variety of strawberries planted at Swanton Berry Farms are grown primarily for taste, and are not considered to be a high yielding variety. In addition, the area where the farm is located is not conducive for achieving the highest yields possible with the variety currently grown.

Slightly lower yields are offset by higher prices paid for certified organic strawberries (Gliessman et al. 1990). For example, production costs range from $18,919 to $23,668 and $20,480 to $24,437 per acre for organic vs. conventional strawberry production practices (See Table 1). In the first two years, input costs associated with pesticides, fertilizers, and fuel were higher in conventional strawberry production; however, organic production practices require more hours of tractor work for mechanical weeding and longer picking times, resulting in higher labor costs for organic strawberry production (Gliessman et al. 1996). Price premiums of up to 50 percent or more have been attained by Swanton Berry Farms. As a result, profits range from $3,039 to $9,738 for organic strawberries compared to $2,303 to $6,087 per acre for conventional strawberries (Gliessman et al. 1996). As demonstrated by these values, organic strawberry production can be profitable. In fact, compared with traditional, chemical-intensive production practices, results indicate that organic strawberries were 83 percent and 60 percent more profitable in the second and third years, respectively (Liebman 1994).

Table 1. Comparative Strawberry Production Costs and Returns ($/acre)

Cultural labor Materials & field power Interest on working capital Total costs
Organic

($/Acre)

Year 1

Year 2

Year 3

9,613

10,094

8,377

10,770

12,176

9,144

1,397

1,397

1,397

21,780

23,668

18,919

Conventional

($/Acre)

Year 1

Year 2

Year 3

8,194

8,755

8,446

13,474

14,148

10,500

1,534

1,534

1,534

23,346

24,437

20,480

Source: Gliessman et al. 1996

The labor and material costs for each of the three years were based on a combination of grower estimates and University of California Cooperative Extension standard cost-of-production data for winter planted strawberries on the Central Coast. Adjustments were made to account for management changes in the second and third years in addition to a 5 percent annual increase in operating costs over baseline for both production practices. Yield and income were calculated by combining the observed yields on a plot basis with average market prices for the season reported by the grower (Gliessman et al. 1996).

The relatively high return on organic strawberries (especially in the third year) must be considered in light of the fact that 1) the study took place when growing conditions (land which was not previously used for strawberry production) and prices for organic strawberries were favorable, 2) costs and returns were based on relatively small-scale operations, which may not translate to larger operations with current production timing and practices, and 3) the cost and returns reported do not reflect the cost of fallow periods typically used in organic strawberry production (i.e., when land is cover cropped and no returns are realized). However, planting marketable cover crops on fallowed fields may compensate for lost revenue. Furthermore, cost savings were realized in the absence of fallow periods in both conventional and organic crops. For example, leaving plants in the ground for several years, as opposed to fallowing the fields, saves on replanting and weeding costs. Additionally, costs were saved by not having to fumigate conventional crops with methyl bromide (Gliessman et al. 1996).

References

Baker 1996 (September). Personal Communication. Brian Baker. California Certified Organic Growers. Santa Cruz, California

Braun and Supkoff. 1994. Options to methyl bromide for the control of soil-borne diseases and pests in California with reference to the Netherlands. A. Braun and D. Supkoff. Pest Management Analysis and Planning Program, State of California. PM 94-02.

Cochran 1996 (September). Personal Communication. J. Cochran. Swanton Berry Farms. Davenport, California.

Cochran 1995 (February). Personal Communication. J. Cochran. Swanton Berry Farms. Davenport, California.

Gliessman et al. 1996. Conversion to organic strawberry management changes ecological processes. S.R. Gliessman, M.R. Werner, S.L. Swezey, E. Caswell, J. Cochran, F. Rosado-May. California Agriculture. Volume 50, Number 1, pp. 24-31.

Gliessman et al. 1994. Conversion to an organic strawberry production system in coastal central California: a comparative study. S.R. Gliessman, M.R. Werner, S.L. Swezey, E. Caswell, J. Cochran, F. Rosado-May. Agroecology Program, University of California. Santa Cruz, California

Gliessman et al. 1990 (July/August). Strawberry production systems during conversion to organic management. S.R. Gliessman, S.L. Swezey, J. Allison, J. Cochran, J. Farrell, R. Kluson, F. Rosado-May, and M. Werner. California Agriculture. Volume 44, Number 4, pp. 4-7.

Larson and Shaw 1994 (November 13-16). Evaluation of eight preplant soil treatments for strawberry production in southern California. In 1994 Annual International Research Conference on Methyl Bromide Alternatives and Emissions Reductions: Conference Proceedings. Number 24. Kissimmee, Florida.

Liebman 1994 (July). Alternatives to methyl bromide in California strawberry production. J. Liebman. The IMP Practitioner. Volume 16, Number 7.

Liebhardt et al. 1989. Crop production during conversion from conventional to low-input methods. W. Liebhardt et al. Agronomy Journal. Volume 81, pp. 150-159.

MBRTF, 1995 (September). Alternatives to Methyl Bromide: Research Needs for California. Report of the Methyl Bromide Research Task Force To The Department of Pesticide Regulation and The California Department of Food and Agriculture.

Stance and Ingham 1995 (November 6-8). Suitability of organic compost and broccoli mulch soil treatments for commercial strawberry production on the California central coast. In 1995 Annual International Research Conference on Methyl Bromide Alternatives and Emissions Reductions: Conference Proceedings. Number 19. San Diego, California.

University of California. 1993. UC IPM pest management guidelines. Division of Agriculture and Natural Resources, University of California. Publication #3339.

USDA. 1993 (June). Agricultural chemical usage, vegetables 1992 summary. National Agricultural Statistics Service, United States Department of Agriculture.

Webb. 1994. Personal Communication. R. Webb. Driscoll Strawberry Research. Watsonville, California.

Welch. 1989. Strawberry production in California. N.C. Welch. University of California Cooperative Extension. Leaflet #2959, p. 15.

Welch et al. 1985. Strawberry production and costs in the central coast of California. N. Welch, et al. Agricultural Extension, University of California.

Westerlund. 1994 & 1996. Personal Communication. Frank Westerlund. California Strawberry Commission. California.

Wilhelm and Paulus. 1980. How soil fumigation benefits the California strawberry industry. S. Wilhelm and A.O. Paulus. Plant Dis. Volume 64, pp. 264-270.

Please note that this publication discusses specific proprietary products and pest control methods. Some of these alternatives are now commercially available, while others are in an advanced stage of development. In all cases, the information presented does not constitute a recommendation or an endorsement of these products or methods by the Environmental Protection Agency (EPA) or other involved parties. Neither should the absence of an item or pest control method necessarily be interpreted as EPA disapproval.

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