Canarygrass response to nitrogen and fungicides
A nitrogen fertilization rate of 44.5 lbs N/ac maximized canarygrass seed yield. Foliar fungicide application increased seed yield by 8.5%, and is important in areas where septoria leaf mottle is prevalent. The fungicide application did not improve the responsiveness of canarygrass to N fertilizer, so these two management practices can be managed separately.
Previous research had identified the response of canarygrass to nitrogen (N) and foliar fungicides, but the research was conducted separately so it was not known whether a fungicide application would improve responsiveness to N fertilizer. The objective of this research was to see if N application rate and foliar fungicide application have a synergistic effect on crop growth, grain yield and gross returns.
This study was conducted in 2012 and 2013 across 5 locations at Melfort, Indian Head, Swift Current, Redvers, and Scott, Saskatchewan. Nitrogen application rate was 8.9, 17.8, 26.7, 44.5, 62.3, and 80.1 lbs/ac (10, 20, 30, 50, 70, 90 kg N/ha). The N rates were not adjusted for soil residual N, which ranged from 9 lbs to 46 lbs/ac (10.1 to 51.6 kg/ha) across the site years.
A foliar fungicide application of Stratego (propicoazole + trifloxystrobin) was applied at the flag leaf stage for leaf disease control, and compared to a control without fungicide application.
A no-till drill with hoe openers was used to seed CDC Bastia canarygrass at a rate of 39 pounds per acre (35 kg/ha). All fertilizer was sidebanded, including 17.8 lbs P2O5/ac (20 kg/ha), 8.9 K2O/ac (10 kg/ha), 5.8 lbs Cl/ac (6.5 kg/ha) and 8.9 lbs S/ac (10 kg/ha).
Canarygrass responsive to increasing N rate and fungicide application
There was a small linear decrease in kernel weight of 2.6% as N rate increased. Kernel weight was not affected by fungicide application.
There was a small increase of 1.6 inches (4 cm) in plant height as N rate increased, but was not of agronomic significance. There was a small, linear increase in lodging, moving from 1.0 to 2.4 as the N rate increased, but this did not impact grain yield. Fungicide application did not affect lodging, and there was no interaction of N rate and fungicide on lodging.
Leaf disease pressure was relatively low, averaging 3.6 out of 11 rating on the untreated control and 2.2 in the fungicide treatments. This difference, though was not significant. However, at 4 of 9 site years, foliar fungicide application reduced the disease rating by at least 1 point. These sites were at Indian Head and Scott, where large commercial fields of canarygrass are grown nearby, and inoculum of Septoria leaf blotch could have infected the plots from these fields. At these sites, disease ratings from 5.7 to 8.2 were observed.
Nitrogen application rate did not have an effect on disease ratings.
Maturity was delayed slight, by less than one day, with increasing N rate, and no delay was caused by fungicide applications.
Even though the application of a foliar fungicide did not significantly reduce overall disease pressure, it did significantly increase grain yield by 8.5%. Yield was 20.3 bu/ac (1139 kg/ha) in the untreated treatments and 22 bu/ac (1236 kg/ha) with a fungicide application. This increased yield was the result of increased kernel density with the fungicide either helping to increase seed set at anthesis or prevent seed abortion during seed filling.
As N rate increased from 8.9 to 80.1 lbs N/ac, grain yield increased significantly from 19.3 bu/ac (1087 kg/ha) to 22 bu/ac (1243 kg/ha), a linear increase of 14.4%. There was no interaction between N rate and fungicide application on yield. This indicates that N fertilizer and disease control with fungicide application can be managed separately.
Grain yield response of annual canarygrass to increasing nitrogen rates
Source: May et al. 2021
Gross returns were calculated using 3 N fertilizer prices ($0.23, $0.34 and $0.45/lbs N) and 3 grain prices ($10, $15, and $20/bu). Under most of the combinations, changes in gross returns were not significant. As a result, a N fertilizer rate cannot be recommended based on gross returns.
The researchers concluded that the 44.5 lbs N/ac rate would maximize yield and economic returns, and that this rate would not change if the cost of N was significantly increased. Also, management of leaf disease with a foliar fungicide did not increase canarygrass response to N fertilizer.
Funding was provided by Saskatchewan Ministry of Agriculture, the Canaryseed Development Commission of Saskatchewan and Agriculture and Agri-Food Canada.
William E. May, Joseph C. Train, and Lindsey Greidanus. Response of annual canarygrass (Phalaris canariensis L.) to nitrogen fertilizer and fungicide applications. Canadian Journal of Plant Science. 102(1): 83-94. OPEN ACCESS: https://doi.org/10.1139/cjps-2020-0221