Page 222 - Plant Canada 2024 Proceeding

PLANT CANADA 2024

[P37] THE ROLE OF ASCOSPORE RELEASE OF ANISOGRAMMA ANOMALA IN THE
1
MANAGEMENT OF EASTERN FILBERT BLIGHT IN ONTARIO, CANADA. Asifa Munawar , Cathy
Bakker , Melanie Filotas , and Katerina Serlemitsos Jordan . Department of Plant Agriculture, Ontario
1
2
1 1
Crop Research Centre, University of Guelph, Simcoe, Ontario, Canada, N3Y 4N5; and Ontario Ministry
2
of Agriculture, Food and Rural Affairs, Ontario Crop Research Centre, Canada, N3Y 4N5
Correspondence to: munawara@uoguelph.ca

Although hazelnuts have been grown in Ontario for decades, their popularity in the province has
increased considerably in the last ten years. One of the greatest threats to their production is the disease,
eastern filbert blight (EFB), caused by the fungus Anisogramma anomala. The fungus releases
ascospores that infect actively growing stem tissue in young shoots. Our current recommendations for
spore release and fungicide application timing are based on research from Oregon, which has a different
climate than Ontario. The goal of this project was to determine the ascospore release of A. anomala
under Ontario weather conditions in order to target applications of preventative fungicides. GRIPST-2009
spore samplers were used to track airborne spores from March-October 2022-2023 at site 1 and site 2 in
Norfolk County, Ontario. Sampling rods were collected 2-3 times per week at each site in 2022-2023
except the site 2 where daily data was collected from April-June 2023. The rods were stained in aniline
3
blue solution and examined microscopically for fungal ascospores, and spore density (Particles/m ) for
each period was recorded. Meteorological data (temperature, rainfall) and phenology data on the cultivar,
‘Jefferson’ for both sites were also recorded. The first ascospore release at site 1 and site 2 coincided
with bud-break (BB, April 18-22, 2022, and April 14-17, 2023, respectively). The highest release for site 1
3
3
(6 P/m in 2022 and 275 P/m in 2023) and site 2 (907 P/m3 in 2022 and 1343 P/m3 in 2023) was
observed from the middle to end of May, close to the mature leaf stage (Growth stage 17-19). Site-1 had
a low spore count in both years. Ascospore release was not observed before April and after June in either
year. SAS multiple regression analysis indicated that total rainfall was significantly correlated with spore
release in 2023 based on data from daily collection periods. Starting from BB spore release continued for
9 weeks in 2022 and 11 weeks in 2023. In Ontario, the standard spray program is 4 sprays at 2-week
intervals starting at BB. Our data indicates the spores of EFB are present in Ontario orchards outside of
the current recommended spray period. More years of data are needed to comprehend the aspects of
changing weather conditions to accurately reflect spore release patterns. Our results merely provide a
platform to build a future forecast model for Ontario growers to accurately time their management sprays.

[P38] PROFILING AVIRULENCE GENES OF LEPTOSPHAERIA MACULANS FOR RESISTANCE
DEPLOYMENT IN CANADIAN PRAIRIE REGIONS. Chun Zhai and Gary Peng. Agriculture and Agri-
Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada
Correspondence to: gary.peng@agr.gc.ca

Genetic resistance is crucial for managing blackleg disease in canola. Additional R genes are being
deployed in canola cultivars grown on in western Canada, but effective use of these R genes requires
understanding the pathogen race structure and dynamics in different regions. In this multi-year study,
thousands of blackleg samples were collected from commercial fields across various crop districts during
canola disease surveys organized by the prairie provinces in 2022 and 2023. Isolates of L. maculans
were analyzed for the presence/absence of 12 avirulence (Avr) genes using KASP markers (AvrLm1, 2,
3, 4, 5, 6, 7, 9, 11, S/Lep2) or host differentials (AvrLm10,Lep1).

Across the region, AvrLm3, 5, 6, 7, 10, and 11 were prevalent, each present in over 80% of the pathogen
populations from the prairie provinces. This suggests that canola cultivars carrying any of the
corresponding R genes, such as Rlm5, Rlm6, Rlm7, Rlm10, and Rlm11, will likely be highly resistant to
blackleg. However, despite the common presence of AvrLm3, the corresponding R gene Rlm3 may be
ineffective due to the high frequency of AvrLm7 in the pathogen population, which masks the effect of
AvrLm3. Relatively, AvrLm2 was more abundant in Saskatchewan, while AvrLm4 was found at
substantially lower frequencies in Alberta.

More than 60 races were identified within the pathogen population, indicating a high degree of diversity.
Virulent races were present for most of the known R genes, except for Rlm10, highlighting the risk
associated with deploying new R genes. Spatial and temporal deployment of R genes may be considered

221