Two passionate soil ecologists in British Columbia
Organic Agriculture Centre of Canada
When she moved from Saskatchewan to British Columbia eight years ago, Louise Nelson brought with her over 100 strains of soil bacteria that she wanted to test against tree fruit replant disease, a disease that affects young trees planted in old apple orchard blocks.
Replant disease happens around the world, but what causes this problem is not understood. When growers pull out old trees out of their orchards and put in their places new varieties, the new trees do not always thrive. Some explanations have been proposed, with one theory suggesting that perhaps when the same species are grown in the same place for a long time, a population of soil pathogens may be built up that negatively affects the new seedlings.
Gerry Neilsen, an AAFC researcher at the Summerland’s Pacific Agri-Food Research Centre (PARC), showed that replanted trees respond well to the addition of phosphorus. Given the importance of phosphorus in young tree establishment, Louise Nelson and other researchers have focused on improving the availability of phosphorus in organic production systems, where synthetic sources cannot be applied.