A comparative study of Dibotryon morbosum (Sch.) Th. & Syd. on peach and plum showed the life cycle to be the same on both hosts. Peach knots were less prominent and produced very few mature perithecia. Plum inoculum was considered to be largely responsible for infections on the peach. The morphology and cultural characteristics of the isolates from the two hosts were similar. Ascospores from plum knots readily infected peach seedlings but those from peach knots did not infect peach or plum seedlings. The colonization of knots by extraneous organisms affected the maturation of perithecia. Of the fungicides used thiram was the most satisfactory for the control of black knot on plum. These investigations indicate that black knot is not of serious economic importance on peach.

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colletotrichum dernatiunt.".r"ut"r:l%ff " ", A culture seeding rate of 2@,000 spores/ml was required for optimum spore production with t. demati.zm. Opiimum growth and sporulation occurred at 22" to 24"C. Growth and soorulation of the funsus was inhibited at 5' and 3l'C and 10" and 29'C. respectively. C.,dematium may not be an important pathogen of beets as it only occurred where beets were grown successively in the same soil.

The crowns and roots of 100 cold-stored, apparently healthy strawberry plants of each of the varieties Acadia, Catskill, Cavalier, Gorella, Guardsman, Midway, Redcoat, Sparkle, and Surecrop were examined for their fungal content. Crowns contained representatives of 43 genera; roots contained 38, of which 36 were in both crowns and roots. Strawberry foliar and fruit pathogens were present in a relatively small number of the crowns and roots. In general, Chaetomium spp. and Fusarium spp. were the most prevalent. Chaetomium cochliodes was more prevalent in Cavalier and Redcoat, the varieties most susceptible to root rot in the field, than in the other varieties. The crowns and roots of apparently healthy, dormant strawberry plants contained a fungal flora similar to that associated with the black root rot complex.One fungus, Varicosporium elodeae, isolated from strawberry plants has not previously been reported in Canada.

INTRODUCTION