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United States Department of Agriculture

Agricultural Research Service

Research Project: EFFICACY OF BIOCONTROL AGENTS APPLIED TO BARE-ROOT CONIFER SEEDLINGS GROWN UNDER MINIMAL BUFFER ZONE RATES OF SOIL FUMIGATION
2011 Annual Report


1a.Objectives (from AD-416)
(1) Assess the efficacy of applied multiple biocontrol agents (e.g., Bacillus subtilis, Streptomyces lydicus, Gliocladium virens, and Trichoderma harzianum) to augment control of root pathogenic fungi (Fusarium, Pythium and Cylindrocarpon) in seedlings growing in soils treated with low levels of chemical fumigants (25-foot buffer rates using TIF tarps); (2) Apply PCR-based techniques to soil and seedling samples to assess Cylindrocarpon spp. present in PNW nurseries; (3) Quantify efficacy of various fumigants combinations on buried Cylindrocarpon inoculums; (4) Assess the economic viability of each treatment; and (5) Conduct educational outreach to project stakeholders


1b.Approach (from AD-416)
Four fumigant treatments (including an untreated control) will be applied at two forest nurseries according to a randomized complete block design with four blocks. Four biocontrol treatments (including an untreated control) will then be applied within each fumigant-treated plot for a total of sixteen treatments. Douglas-fir seedlings will be planted into each fumigant × biocontrol treatment plot and assessed for growth. Soil will be assayed by standard dilution plate procedures for the presence of Cylindrocarpon, Fusarium, and Pythium species before and after the application of fumigant and biocontrol treatments, and at the termination of the experiment. Weed populations will be quantified within each broader fumigation plot after Douglas-fir seedlings have been planted. Documents SCA with University of Washington.


3.Progress Report

We are trying to determine whether biocontrol agents control Pythium, Cylindrocarpon, and Fusarium pathogens in forest nurseries. All three fungi cause mortality of conifer seedlings. To date, we have planted Douglas-fir seedlings into field plots and applied the first round of three applications of four biocontrol treatments. Population estimates of each of the three pathogens in the soil and on the seedlings were determined prior to the first round of biocontrol treatment applications and will be compared to soil and seedling pathogen populations at the end of the experiment.

Presented data to forest nursery managers, federal and state regulators, and researchers interested in methyl bromide alternatives at the 2011 Annual International Research Conferences on Methyl Bromide Alternatives and Emissions Reductions and at stakeholder meetings.

Methods of project monitoring included meetings, e-mail, and phone calls.


Last Modified: 12/21/2014
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