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The potential for widespreadand severe infection makes ascochyta blight,seedling blight, and root rots major hindrancesto pea production in Alberta, Canada. Over 300bacterial strains were isolated from pea seedand soil samples taken from pea fields. Thesestrains were investigated for their biologicalcontrol potential against four fungal pathogens(Pythium ultimum, Rhizoctoniasolani, Fusarium avenaceum and Ascochyta pisi) of field pea in vitro. Selected bacterial strains were furtherevaluated in vivo. In an initial agarplate bioassay, 30 strains exhibitedantagonistic properties against the fourpathogens, with inhibition zones ranging from 5to 25 mm. Thirteen of these strains, allisolated from soil, inhibited only one or twoof the pathogens, while the remainingseventeen, including nine strains isolated frompea seeds, inhibited either three or all fourpathogens. In a more stringent bioassay, eightof the thirty strains failed to demonstrate theantagonistic features shown in the initialbioassay. Eight strains inhibited only onepathogen, six inhibited two, four inhibitedthree, and four strains inhibited all fourpathogens tested. Two strains ofPseudomonas fluorescens, five strains of Serratia spp. and two strains of Bacillus spp. were further evaluated ingreenhouse experiments. Five of the isolatesreduced the severity of diseases caused byPythium or Ascochyta, two isolatesreduced the severity of Rhizoctonia andone reduced the severity of Fusarium. |
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