Skip to main content
ARS Home » Pacific West Area » Parlier, California » San Joaquin Valley Agricultural Sciences Center » Water Management Research » Research » Publications at this Location » Publication #259502


item HANSON, BRADLEY - University Of California - Cooperative Extension Service
item Gao, Suduan
item Gerik, James
item Wang, Dong
item QIN, RUIJUN - University Of California
item CABRERA, J. - University Of California
item JHALA, A. - University Of California

Submitted to: International Conference on Methyl Bromide Alternatives and Emissions Reductions
Publication Type: Proceedings
Publication Acceptance Date: 9/1/2010
Publication Date: 11/1/2010
Citation: Hanson, B., Gao, S., Gerik, J.S., Wang, D., Qin, R., Cabrera, J.A., Jhala, A. 2010. PACIFIC AREA-WIDE PROGRAM: CURRENT STATUS OF THE CALIFORNIA PERENNIAL NURSERY SECTOR. International Conference on Methyl Bromide Alternatives and Emissions Reductions. p.27-1 - 26-2.

Interpretive Summary: The Pacific Area-wide Pest Management Program for methyl bromide alternatives is a scheduled 5 year program from 2008 through 2010. One sector of this program is for the perennial crop nursery industry. The nursery industry still relies heavily on methyl bromide use because of the state certification process which requires the crop to be totally free of plant parasitic nematodes. While methyl bromide use as been phased out for most commodities the nursery industry has used the quarantine/preshipment (QPS) exemption to continue its use. There is concern in the industry that the QPS exemption could be cancelled in the future due to political pressure. During the first 3 years of this program the emphasis was on pest control efficacy and emission reductions. The options for alternative fumigants in the nursery industry are limited due to requirements of the certification process and the effectiveness of the alternative chemicals. Alternative approaches will likely rely more on the use of herbicides for weed control, the second most important aspect of pest control after nematode certification. The final 2 years of this project will focus on completing the previous multiyear trials and technology transfer to the nursery industry.

Technical Abstract: The perennial crop nursery industry supplies over 60% of the total fruit, nut, and rose plants sold in the USA. Although methyl bromide (MB) use has decreased in many California industries due to the phaseout, perennial nursery producers largely continue to use MB under Critical Use Exemptions (CUE) and Quarantine/Preshipment (QPS) criteria allowed under the provisions of the Montreal Protocol. Recent meetings of the Parties to the Montreal Protocol have resulted in significant reductions in Critical Use Exemption MB use in several commodities and this trend may lead to substantial impacts on the California nursery industry. Additionally, while QPS use of MB is regulated by individual countries, the nursery industry is concerned that political pressures may eventually result in limitations on QPS uses of MB before viable alternatives are developed. In comparison with other fumigation-dependant industries, perennial nursery stock producers face a more difficult transition to alternatives due to regulatory constraints and, clearly, adoption of MB alternatives in California nurseries has been slow. The primary factor slowing adoption of MB alternatives in California are state regulations related to the Nursery Stock Nematode Certification program. In order to be certified as nematode-free (and, thus, saleable) nurseries must either use an approved treatment or undertake a comprehensive soil and root sampling program. The current threshold for parasitic nematodes in California nurseries is “detection”. In the first several years of the Pacific Area-wide Pest Management Program, the perennial nursery project focused on testing and demonstrating emission reduction techniques while simultaneously evaluating the effects of these practices on pest control efficacy. During the final two years of the project, efforts will center on completing the initial multi-year projects and related spin-off research and are being redirected towards demonstration of viable alternative fumigants and herbicides for integrated pest management in commercial nursery fields. As the projects come to a close in 2012, technology transfer efforts will take the forefront in the project. In the long term, development and adoption of integrated approaches to soil-borne pest management will be critical. Fumigant options in perennial crop nurseries are severely limited by nematode certification, thus short-term solutions are likely to include chemical fumigants. After nematode certification requirements, weed control remains one of the largest management issues and economic considerations in nursery pest control. Most California nurseries rely on preplant fumigation followed by extensive tillage and hand weeding to maintain acceptable weed control during the growing season. Some growers also utilize herbicide applications; however, herbicide options are very limited in nurseries and many growers are not comfortable with the risk of crop injury. As alternative fumigants are phased in and labor and fuel costs continue to rise, herbicides are likely to become a more important weed management tool in perennial crop nurseries. In the final phase of the perennial crop nursery sector’s Area-wide project, we plan to continue technology transfer efforts and will develop and demonstrate integrated approaches which combine available and emerging fumigant alternatives with effective herbicides for management of the broad soil-borne pest spectrum found in open-field nurseries.