OUTLOOK: Specialty crops and methyl bromide alternatives: Taking stock after 7 years

Abstract

finding alternatives to Outlook Specialty crops and methyl bromide alternatives: taking stock after 7 years Greg T. Browne Research Plant Pathologist, Crops Pathology and Genetics Research Unit, USDA-ARS, Department of Plant Pathology, University of California, Davis S Jack Kelly Clark pecialty crop farms and nurseries in Califor- nia, Oregon and Washington provide local and world markets with abundant fruit, nut and vegetable crops and planting stock. These op- erations thrive due to dedicated human investment and the availability of precious combinations of soil, climate and water resources. California alone produces 99% of the U.S. almond and walnut crops and 90% of the strawberry crop, and it supplies 99% or more of U.S. almond, raisin, table grape and walnut exports. Combined, California, Oregon and Washington account for roughly 32% of the U.S. floriculture crop value, 44% of the nursery crop value and 78% of the fruit and nut crop value. Pest-free nursery stock We all have a large stake in the availability of and productive specialty crops. Research increasingly documents soils are vital their benefits to our health. They are a livelihood, to efficient use directly or indirectly, for many of us. As a society, of land, water, energy and we have contributed collectively to key infrastruc- fertilizer resources tures, such as water resource developments for for specialty crops irrigation and the land-grant college system with such as almonds and grapes. its associated teaching, research and extension Above, an almond functions. Indisputably, ample food production, orchard in bloom. including specialty fruits, nuts and vegetables, is a key measure of national and global security. California Agriculture journal thanks Yet specialty crop farming faces the faculty chairs for this special col- serious challenges. Especially in lection: Greg Browne, Research Plant California, urban growth is remov- Pathologist, USDA Agricultural Research ing farmland irreversibly. Also, Service (USDA-ARS) and Department water resources can be allocated of Plant Pathology, UC Davis, and away from agriculture, and some Brad Hanson, Cooperative Extension specialty crop pest management Specialist, University of California, practices, such as soil fumigation, Davis. We also thank the USDA-ARS are requiring intensive regulation to Pacific Area-Wide Pest Management Program for Integrated Methyl Bromide ensure public safety. Alternatives for helping defray the In 2006, preplant soil fumigation cost of this issue and the upcoming with methyl bromide, an effective October–December 2013 edition. pest management practice used ex- tensively in production of billions of dollars of high-value specialty crops annually, was being phased out due to its contributions to ozone depletion in the stratosphere. Further, the immedi- ate alternatives to methyl bromide, mainly a few other soil fumigants, were on “shaky ground” due to their own environmental challenges. That year, the U.S. Department of Agriculture (USDA) launched the Pacific Area-Wide Pest Management Program for Integrated Methyl Bromide Alternatives (PAW-MBA). The program drew growers, nursery representatives, regulatory officials and scientists from California, Oregon and Washington to work together as a multidisciplinary team in response to the methyl bromide phase-out. Scientists from the USDA Agricultural Research Service, University of California, California Department of Pesticide Regulation, Oregon State University and Washington State University, along with public and private stakeholders, all were vital to development and implementation of the program. The PAW-MBA sought to: 1) optimize avail- able “next-best” fumigant alternatives to methyl bromide soil treatments and 2) foster development of non-fumigant alternatives. Specific needs of the targeted production systems (i.e., perennial and annual nursery crops, strawberries, almonds and stone fruits, walnuts and grapes) as well as over-arching environmental challenges (e.g., hu- man health and safety; air, soil and water quality; efficient use of environmental resources) would be accommodated. In the absence of methyl bromide, specific needs varied among the different production systems. Field nurseries needed alternatives to manage weeds (effective herbicides were not available) and nematodes (certification requires nursery stock to be nematode-free) over 1- to 2-year plant pro- duction cycles, and there was little flexibility for non-fumigant alternatives. In contrast, orchardists had less need to control weeds and more pressing needs to manage soilborne pathogen complexes (including but not limited to nematodes) over 15- to 30-year production cycles. Compared to field nurs- eries, orchard, vineyard and strawberry produc- ers had more flexibility to explore non-fumigant alternatives. All of the PAW-MBA specialty crop systems shared the imperative to minimize non-target fu- migant emissions to the atmosphere. Fumigants are hazardous, volatile, broad-spectrum biocides and are regulated accordingly at federal, state and county levels to keep bystanders safe and minimize http://californiaagriculture.ucanr.edu • JULY–SEPTEMBER 2013