Eradication Trial Of Annosus Root Rot In Red Pine Plantations

In 1989, Heterobasidion annosum was first detected in Quebec, Canada, in a 50-year-old red pine plantation. In 1992, the 18 ha plantation was surveyed systematically and 12 centres of annosus roof rot were detected. Since these centres were relatively small, an eradication trial of the disease was designed. II June 1993, all infected trees and stumps were marked as was one row of apparently healthy trees surrounding the infected trees and stumps. Trees were harvested, the stumps were removed, carried to a dump or buried on site and covered with 1 m of sand. Also, the top soil and the organic matter were scraped away from the surface, buried on the site and covered with 1 m of sand. In December 1994, similar treatments were applied to a second red pine plantation where only one infected centre was found. Then, on these two sites, two-year-old red pine seedlings were planted in all treated areas as bioindicators of the disease. These seedlings have been inspected every year since. In 1996, a second survey was done to detect any new infection centres. Diseased seedlings were detected in only one centre. Fruiting bodies of H. annosum were also found at the limit of three treated areas. A new infection centre was found very near two small ones detected in 1992. In conclusion, it is possible to eradicate the disease on relatively small infected sites but one must be cautious about the old stumps in the vicinity of the infection centres. Also, quality control of the work must be maintained during and after the work is carried out.