Page 141 - Plant Canada 2024 Proceeding

PLANT CANADA 2024

pasture mixes available on the market. The three fertility treatments to be tested include: 1) zero fertility
control, 2) a one-time spring application/year of 19-19-19 NPK fertilizer, or 3) fertilize as needed
according to OMAFRA guidelines based on soil testing. Forage yield was analysed for three years and
forage quality analysis in the first year. Overall, our results have shown that the treatment fertilized
according to OMAFRA recommendations yielded the most in each year and over the three years. The
differences in yield between this treatment and the other two treatments grew with time, suggesting
nutrient deficiencies were becoming more severe. By year 3, applying 100 lbs of 19-19-19 does not seem
to increase the yield relative to the no fertilizer control. Grass-legume mixtures provided greater yields
than those of solely grass-based mixtures and also do not require nitrogen applications, making them
highly profitable. If planting a pure grass forage, over a 3-year period, grass mixtures yielded better than
single grass species. The red clover-based mixture yielded more in the first year, whereas after that the
alfalfa-based mixtures yielded more, ultimately being more productive across all three years of the study.
Tissue potassium concentrations were lower compared to tissue phosphorus in the 19-19-19 NPK and
the no fertility treatments. Hence, low soil extractable potassium concentrations may impact forage yield
more than low soil test phosphorus concentrations; thus, potassium should not be underestimated when
applying fertility to forages. However, the transferability of our study to other sites will vary depending on
starting soil fertility levels, thus it is recommended to soil test your forage fields regularly to know your
starting point.

*[O80] EFFECT OF ENHANCED EFFICIENCY NITROGEN FERTILIZERS ON AGRONOMIC AND
ENVIRONMENTAL PERFORMANCE IN GRAIN CORN. Baillie Lynds and Yunfei Jiang . Department of
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Plant, Food and Environmental Sciences, Faculty of Agriculture, Dalhousie University, Truro, NS,
Canada, B2N 5E3
Correspondence to: baillie.lynds@dal.ca

Enhanced-efficiency nitrogen fertilizers (EENFs) have the potential to improve crop yield and nitrogen (N)
use efficiency while reducing N loss and protecting the environment. There are different types of EENFs,
including slow-release, control-release, and stabilized N fertilizers. Previous research showed that the
impact of EENFs on greenhouse gas (GHG) emissions and grain yield is inconsistent, as the efficacy of
EENFs is variable depending on the soil type, temperature, humidity, microbial activity, availability of
water, and crop species. The efficacy of EENFs in cereals in Maritime Canada has not been well-
documented. The objective of this project is to evaluate the effects of different types, rates, and split
applications of EENFs on environmental and agronomic performance in grain corn at two sites in Maritime
Canada over two years. Our preliminary results from the 2023 field trial conducted in Truro, Nova Scotia
showed that (1) fertilizer treatments increased grain yield compared to no fertilizer control; (2) EENF
reduced environmental impact without yield penalty; (3) reduced N rate did not impact grain yield; and (4)
single application at planting did not affect grain yield and residual soil nitrate concentrations immediately
after harvest compared to split applications. Our findings will provide recommendations to growers
regarding the best type, and the optimum rate and N split application timings of EENFs in grain corn and
help improve food security and the overall sustainability of the agricultural industry.

*[O81] MECHANISMS OF DEMETHYLATION INHIBITOR RESISTANCE IN CLARIREEDIA
JACKSONII. E. McNab and T. Hsiang. School of Environmental Sciences, University of Guelph, 50 Stone
Road East, Guelph, ON N1G 2W1, Canada.
Correspondence to: emcnab@uoguelph.ca

Dollar spot (caused by Clarireedia species) is one the most prevalent and costly diseases affecting
turfgrasses in the North American Great Lakes region. With the high aesthetic standards for turfgrass
appearance by turf managers and users, fungicides are heavily and frequently used which can lead to
issues of resistance. Demethylation inhibitors (DMIs) are a commonly used class of fungicides to manage
these diseases. The mode of action is the inhibition of biosynthesis of ergosterol, which is an essential
component of fungal cell membranes. Since the first report of DMI resistance in 1981, reports have
become increasingly common in many plant pathogens. There is ample literature investigating the
mechanisms of DMI resistance (i.e., mutations affecting the CYP51 proteins, xenobiotic detoxification,
and the expression of efflux transporters) in a wide range of fungi, but research into characterizing the
mechanisms in the Clarireedia is still ongoing with only a few documented genetic elements associated

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