Abstract
Postplanting weekly or biweekly applications of metalaxyl at 0.312 mg or 0.600 mg a.i. L−1 soil were as effective as steam sterilization in controlling apple replant disease (ARD) symptoms in greenhouse studies. Growth improvements obtained with metalaxyl suggest that Oomycetes may be involved in ARD in Quebec. In orchard trials plastic mulch, as a cultural treatment, was found to be as effective as methyl bromide, chloropicrin and formalin against ARD; metalaxyl, Vorlex and nitrogen were found to be less effective.Key words: Replant, apple, Malus pumila Mill., Pythium, mulch