A COMPARISON OF GROWTH, LIFE CYCLE AND CONTROL OF DIBOTRYON MORBOSUM (SCH.) TH. & SYD. ON PEACH AND PLUM IN NOVA SCOTIA

Abstract

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.

Effects of Black Knot Disease on Pin Cherry

“…Drenching the seedlings with ascospore suspensions did not result in detectable infection in this study but has been successful in other investigations (2,6,11). Inoculation with conidia produced in culture has had limited success (11) but may merit further investigation.…”

“…The disease is readily recognized by black stem-and branch galls, which support mature stromata of the causal fungus. On cultivated orchard crops, black knot causes losses in fruit production (2,5,10), but its impact on native Prunus spp. is unknown (3,12).…”

“…Stromata of densely packed perithecia form in late summer and autumn, and mature during the following spring. Numerous insects and fungi invade the mature stromata or galls and limit ascospore production (2,6).…”

“…morbosa has been isolated in pure culture and produces the anamorph (Hormodendrum sp.) on culture media (2,6,11). The role of this stage in the life cycle of the fungus is uncertain (11).…”

Molecular and morphological characteristics ofApiosporina morbosa, the causal agent of black knot inPrunusspp.

“…Previous studies have shown that various strains of the pathogen may have some specificity to certain host plants. Gourley (1962) reported that ascospores from plum knots readily infected peach seedlings, but those from peach knots did not infect peach or plum seedlings. Similarly, Smith et al (1970) were unable to induce the black knot disease in P. domestica 'Stanley', using ascospores from Prunus serotina Ehrh.…”