2020 HINDSIGHT ON THE NORTH AMERICAN BARLEY EVALUATION NURSERY (NABSEN)

Barley production in the Midwestern U.S. and Prairie provinces of Canada is severely threatened by the
decades long issue of Fusarium head blight (FHB) and contamination of the mycotoxin deoxynivalenol
(DON). The malt barley industry is particularly impacted by FHB with tolerances for DON below 0.5
ppm. The mandate to address breeding FHB resistance in barley was initiated in 2002 when the first
uniform field trial nurseries were established giving rise to the North American Barley Evaluation
Nursery (NABSEN). For the past 18 years and counting, NABSEN has provided coordination and
insights necessary for malt barley breeders to select for high levels of resistance against FHB and DON
in their germplasm. Elite barley lines are planted each year from university cooperators and industry
partners. Five misted nurseries comprising NABSEN are located in the state of North Dakota, Minnesota,
and the Canadian province of Manitoba providing a broad range of barley growing regions. Lines are
planted in short rows (1.2 m long) in a random controlled block design. Each line is planted in three
replicates with consistent checks. Corn spawn and/or macroconidia are used as inoculation sources.
FHB evaluation is determined at Feekes 11.2 growth stage (soft to mid-dough). Severity and DON are
measured using a robust procedure to ensure uniformity over the years. Performance of the NABSEN
nurseries varies yearly with dynamic changes in weather conditions and yearly refreshing of barley
lines being evaluated. However, a clear trend of increased FHB and DON is observable from the first
9 years (2002-2010) to the second 9 years (2011- 2019). Increase in overall average severity of 41.7%
and DON of 18.8% comparing the first and second decades. This trend could be due in part to better
strategies for inducing disease, but are also likely impacted by more favorable climate conditions in
recent years. Performance of the 10 top and bottom barley lines compared to the resistant and susceptible
checks show a trend of increased FHB resistance over the decades. Top 10 lines showed 13.4% low
severity and 13.3% low DON compared to the resistant checks over the decades. Bottom 10 lines showed
5.7% lower severity and 18.3% lower DON compared to the susceptible checks over the decades. This
is encouraging results despite the increased disease pressure. The complex nature of FHB resistance
in barley requires continued coordinated strategies, such as NABSEN, to make progress in breeding
resistance. The coordinated program will be dedicated to providing even better FHB evaluation using
advanced screening tools, such as biomass and hyperspectral measurements, to aid barley breeders in
developing FHB resistance in their elite barley lines well into the future.