Khalil I. Al-Mughrabi, Appanna Vikram, Rick D. Peters, Ron Howard, Lucie Grant, Tharcisse Barasubiye, Keith Seifert, Robert Shoemaker, Kelvin Lynch, René Poirier, Kathy A. Drake, Ian K. Macdonald, and Sherry Lisowski
Partner: Potatoes New Brunswick; JET Harvest Solutions, Florida, USA.
Abstract: Helminthosporium solani, the cause of silver scurf, and Fusarium spp., the cause of dry rot of potato have recently
developed resistance to thiabendazole, a post-harvest fungicide. The present study tested the biopesticides Bio-Save 10LP and 11LP
(Pseudomonas syringae strains ESC-10 and ESC-11) as alternative means of managing the two diseases. Infected potato samples collected
from New Brunswick (NB), Prince Edward Island (PEI) and Alberta (AB) produced 30 isolates of F. sambucinum, F. tumidum, F. coeruleum,
F. culmorum, F. avenaceum and H. solani. Helminthosporium solani from AB and PEI belonged to two different groups (one group from NB)
according to the internal transcribed spacer (ITS) analysis. Bio-Save 11LP inhibited the growth of F. sambucinum and H. solani while
Bio-Save 10LP was effective only against H. solani in vitro. Thiabendazole alone or in combination with either Bio-Save 10LP or 11LP
significantly reduced the growth of F. sambucinum and H. solani in vitro compared to the control. Fusarium sambucinum from NB was more
sensitive to thiabendazole than that of AB and PEI. Helminthosporium solani from AB were more sensitive to thiabendazole than those from
NB and PEI. Storage trials conducted in NB and PEI assessed Bio-Save as post-harvest biopesticide. Bio-Save or thiabendazole alone or in
combination significantly reduced the incidence and severity of dry rot and silver scurf in both NB and PEI.