Page 209 - Plant Canada 2024 Proceeding

PLANT CANADA 2024

Fusarium wilt disease severity. This finding suggested that genotypes with intricate and expansive root
systems showed increased resistance to Fusarium wilt. The results not only identified potential root
system architectural traits associated with Fusarium wilt resistance, but also underscored the
effectiveness of semi-hydroponics as a reliable and straightforward approach for resistance screening
under controlled conditions.

[P10] BIOLOGICAL CONTROL OF FUSARIUM GRAMINEARUM AND VERTICILLIUM
LONGISPORUM CAUSING FHB AND VERTICILLIUM STRIPE IN CANOLA BY PHYLLOSPHERE AND
RHIZOSPHERE BACTERIA FROM CANOLA AND SOYBEAN. Monika Dayarathne and Dilantha
1
1 1
Fernando . Department of Plant Science, University of Manitoba, Winnipeg, MB, Canada, R3T2N2
Correspondence to: dilantha.fernando@umanitoba.ca

Verticillium stripe in canola is a soil borne disease caused by Verticillium longisporum. Currently, there is
no identified resistance or registered fungicides available to effectively manage this disease. Fungicides
are used to suppress Fusarium head blight (FHB) in wheat, which is caused by Fusarium graminearum
species complex (FGSC). However, the pathogen's ability to evolve defense mechanisms to elude
existing treatments makes the use of fungicides difficult to maintain. Therefore, it would be beneficial to
look for biological agents that are effective in controlling these pathogens to lessen the impact of these
diseases along with chemical control. In vitro and in vivo biocontrol assays were carried out to evaluate
antifungal potential of well-characterized biocontrol agents, Pseudomonas chlororaphis (PA23, soybean
rhizosphere), P. brassicacearum (DF41, canola rhizosphere), and Bacillus amyloliquefaciens (BS6,
canola endophyte) against pathogens causing Verticillium stripe of canola and FHB of wheat. Dual culture
assays with 2 isolates of V. longisporum and 12 F. graminearum isolates (3ADON and 15ADON
chemotypes from Alberta, Manitoba, and Saskatchewan) were conducted and showed that all three
biocontrol agents (BCAs) significantly (p>0.05) suppressed the growth of V. longisporum and F.
graminearum. Greenhouse inoculations also confirmed that BS6 is an efficient biocontrol agent for wheat
FHB and Verticillium stripe of canola. To elucidate the responsible antibiotics involved in PA23, PA23-63:
phenazine-minus and PA23-8: pyrrolnitrin-minus mutant strains were tested against Fg and Vl. Phenazine
and pyrrolnitrin compounds are key secondary metabolites contributing to the antagonistic and antifungal
activity of PA23. However, in PA23, mutations in phenazine and pyrrolnitrin biosynthetic genes exhibited
equal or more antifungal activity in vitro compared to the wild type, which means phenazine and
pyrrolnitrin are not the major products directly contributing to V. longisporum and F. graminearum
biocontrol. However, using a scanning electron microscope, crude extract of bacterial isolates will be
assessed for its capacity to induce structural abnormalities in fungal mycelium for the precise
determination of the biocontrol mechanisms. Further, RFP/GFP transformed isolates of BCA’s and
pathogens will be used to observe the pathogens and BCA’s interactions within the host tissues. In
addition, metabolomic data from both pathogen and BCAs will reveal mechanisms of action of BCAs
during biotrophic, and necrotrophic phases of the pathogen.

[P11] EVALUATION OF DIFFERENT STRATEGIES TO CONTROL STRAWBERRY ANGULAR LEAF
SPOT (XANTHOMONAS FRAGARIAE). Maxime Delisle-Houde , Valérie Tremblay , François Demers ,
1
1
2
Stéphanie Tellier , Gabrielle Labrie , Valérie Fournier , Nicholas Lefebvre , and Russell J. Tweddell .
1
4
3
1
1
1 Département de phytologie, Université Laval, Québec, QC G1V 0A6, Canada; Club les productions
2
Écolo-Max, Lévis, QC G7A 2N7, Canada; Ministère de l’Agriculture, des Pêcheries et de l’Alimentation
3
du Québec, Direction régionale Capitale-Nationale et Chaudière-Appalaches, Québec, QC G1N 3Y7,
Canada; and Département des sols et de génie agroalimentaire, Université Laval, Québec, QC G1V
4
0A6, Canada
Correspondence to: maxime.delisle-houde.1@ulaval.ca

In strawberry (Fragaria × ananassa), the management of angular leaf spot (ALS) caused by the bacterium
Xanthomonas fragariae is difficult due to the lack of effective control methods. In this study, various
strategies were tested for their efficacy to control ALS including leaf stripping, hot-steam treatment, and
application of chemicals registered or not against ALS during a two-years field assay. The chemicals
tested were a copper-based pesticide, sodium carbonate peroxyhydrate, citric acid + lactic acid, hydrogen
peroxide and hydrogen peroxide + peracetic acid. The field assays were conducted in 2022 and 2023
with the cultivar ACC Lila and the cultivar Sonata, respectively. Hot-steam treatment using an airtight
®
plastic pallet box as controlled-atmosphere chamber and copper-based pesticide (Cueva Commercial)
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