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United States Department of Agriculture

Agricultural Research Service

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Location: Floral and Nursery Plants Research

2011 Annual Report

1a. Objectives (from AD-416)
The objectives of this research are to develop taxon-specific DNA-based sampling procedures to quantify Fusarium and Rhizoctonia inocula levels in soil and on bulbs; use this information to develop improved disease controls; and develop sections relating to Fusarium and Rhizoctonia diseases for addition to a new WSU “bulb crop” best management website.

1b. Approach (from AD-416)
ARS will acquire the basic molecular knowledge on identification of Rhizoctonia and Fusarium pathogens of bulb crops. This information will be used by the cooperator to jointly develop taxon-specific DNA-based sampling procedures to quantify Fusarium and Rhizoctonia inocula levels in soil and on bulbs. Based on this knowledge, the cooperator will develop improved disease control strategies and develop Fusarium and Rhizoctonia management recommendation for a “bulb crop” best management website.

3. Progress Report
Ornamental bulbs and flowers are important high-value specialty crops. Maintaining the health of vegetatively-propagated bulbous flower crops is a major challenge for growers. There are a number of fungal diseases, especially those caused by Fusarium and Rhizoctonia, that build up in planting stocks and soil resulting in reduced productivity and increased use of pesticides. Increasing restrictions on the use of pesticides and pesticide resistance in crops also limit grower management options. The overall goals of this project are to develop taxon-specific DNA-based sampling procedures to quantify Fusarium and Rhizoctonia inoculum levels in soil and on bulbs; develop improved disease controls; and develop a “bulb crop” best management web site. Researchers from Washington State University have initiated collecting samples of Fusarium and Rhizoctonia isolates from ornamental bulb crops from grower fields. Pathogens will be identified to specific taxons by molecular approaches, involving real-time PCR assays. Terraclor (PCNB) has been the industry standard for the control of Rhizoctonia gray bulb rot and other soilborne diseases of tulips and iris since the 1950’s. There are increasing environmental concerns about this product and EPA issued a ban on the sale of this product in fall 2010. Researchers are investigating various preplant soil treatment alternatives to Terraclor and their effects on tulip emergence and bulb and flower yield. In an early assessment, and based on emergence and flowering data, both Moncut and Medallion appear to have the potential to be as effective as Terraclor in controlling this disease. Investigators at Washington State University organized the Bulb Grower Conference held on January 26, 2011 that was attended by approximately 20 growers. The program included a discussion of registration issues associated with the use of PCNB on ornamental bulb crops, alternatives to PCNB, and an overview of the objectives and goals of this project. They also hosted a Bulb Grower Field Day on May 11, 2011 in Puyallup, WA that included information on disease and weed identification and provided an opportunity for growers to view the bulb disease management research trials being supported by this project. Research activities conducted under this agreement were monitored by regular email communication, submission of reports by the cooperator, and by in-person communication at scientific and stakeholder meetings.

4. Accomplishments

Last Modified: 07/24/2017
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