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1. To identify a range of P solubilizing bacteria and/or fungi suitable for field testing in fruit orchards.
2. To identify a range of bacteria with plant stimulatory growth effects in soil exhibiting replant disorders.
3. To identify potential composts inhibiting growth reductions associated with replant problem soils.
4. To identify an optimum combination of treatments with high potential for practical use under field conditions.
5. To determine best rhizosphere treatments to achieve optimum growth improvements under field conditions faced by organic growers.
6. To transfer knowledge to the organic agriculture sector.

Replant disorders including poor establishment and retarded growth of new plantings pose serious economic losses in the early years of new perennial fruit plantings in British Columbia where establishment costs can exceed $10,000/hectare.  The problem is particularly acute for organic growers who do not have access to the same arsenal of chemical fertilizers, fumigants and herbicides as conventional growers. Organic soil and orchard floor management is a highly rated research priority in recent surveys of organic growers both nationally and in BC.  Previous research has indicated beneficial growth of apples following judicious use of composts in the planting hole and recent greenhouse experimentation identified phosphate and an auxin-producing root-associated bacterium as two treatments stimulating the growth of test seedlings planted in an existing orchard soil subject to tree decline. These data suggest that P solubilization and root length stimulation are two elements to improve initial plant performance. Other root-associated microorganisms also show potential to enhance root growth and health.

For these reasons, it is proposed to undertake a 3 year study to develop organically-compatible strategies to establish best management practices to improve rhizosphere (root region) health and accelerate the achievement of economic return.  The first year will involve the greenhouse screening of a range of biological amendments, including commercially available biologicals, individual bacterial strains and combinations from a previously established collection of plant growth enhancing rhizobacteria and various locally available, certifiable composts.  The last two years will involve field testing, working directly with organic growers in their orchards in order to assess the most promising treatments or treatment combinations from stage 1 screening.  The study is designed around work to be undertaken by an MSc student completing a thesis and undergraduate summer student research assistants.  The student will be under the direct supervision of Dr. Louise Nelson, UBC-Okanagan.  Dr. Gerry Neilsen, AAFC-PARC-Summerland, will serve on the  advisory committee of the MSc student, assist in greenhouse and field trials and be directly involved in associated soil chemical and plant nutrition determinations.

We anticipate that this research will identify best organic management practices to overcome poor initial establishment of fruit plantings, problems that can lead to yield reductions of as much as 50% in the initial 5 years after replanting. These practices will provide an environmentally benign replacement for fumigant treatments such as methyl bromide which is being phased out due to its depletion of ozone in the atmosphere. We expect to develop an organic inoculant product with commercial potential that along with compost can be readily adopted by organic growers. We will train an MSc student and three undergraduate students in applied soil science and microbiology and field research. This research will enhance the competitiveness of organic growers by increasing yield and lowering production costs while enhancing soil health and quality.

• AAFC Gets to the Root of Organic Fruit Crops in BC
  • OACC News Article. 2012
    
• AAFC Gets the Dirt on Fruit Crops in BC
  • OACC News Article. 2011
• Bacteria may be the solution to replant problems in organic orchards
  • OACC News Article. 2011
• [PDF - 2.2 MB]
  • The Canadian Organic Grower. 2012
• [PDF - 78 kB]
  • Canadian Organic Science Conference. 2012
    
• [PDF - 8.9 MB]
  • The Canadian Organic Grower. 2012
• • HortScience (2010) 12: 1866-1871
• Helping New Trees Thrive in Organic Orchards
  • OACC News Article. 2012

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• • Canadian Journal of Microbiology (2008) 56: 248-258
• • Canadian Journal of Plant Pathology (2001) 23: 1-7
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• • Canadian Journal of Soil Science (2003) 83: 131-137
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