Pasmo disease and lodging in flax as affected by pyraclostrobin fungicide, N fertility and year

Abstract

Vera, C. L., Irvine, R. B., Duguid, S. D., Rashid, K. Y., Clarke, F. R. and Slaski, J. J. 2014. Pasmo disease and lodging in flax as affected by pyraclostrobin fungicide, N fertility and year. Can. J. Plant Sci. 94: 119–126. Severe infection of the fungal disease known as pasmo, caused by Septoria linicola (Speg.) Garassini, reduces seed yield of flax (Linum usitatissimum L.) in western Canada. Pasmo may also indirectly affect seed yield by predisposing flax plants, under favorable weather and soil fertility conditions, to lodge. With the objective of studying the possible association of this disease with the occurrence of lodging and their effect on seed yield, a study was conducted at Melfort, Saskatchewan, Canada, during 4 consecutive years (2009, 2010, 2011 and 2012), with two fungicide regimes (application and no application) and five rates of nitrogen (N) fertilization (0, 33, 66, 100 and 133% of recommended). The application of pyraclostrobin fungicide reduced disease severity and increased seed yield of flax in the 3 yr (2010, 2011 and 2012) that pasmo infection was detected, and prevented or reduced the occurrence of lodging in the 2 yr (2010 and 2012) with favorable weather conditions for the occurrence of lodging. Increasing rates of N resulted in increased seed yield in 2009 and 2012, regardless of whether fungicide was used or not. Increasing rates of N also increased the severity of pasmo disease in 2010, 2011 and 2012, and of lodging severity in 2010 and 2012. The increase in disease severity due to N occurred in the absence of fungicide in 2011 and when fungicide was applied in 2012, while in 2010 just the effect of N on the two fungicide treatments combined was significant. Only low levels of disease severity (near 20%) were observed when fungicide was applied in 2011, while extreme disease severity (near 100%) occurred in 2012 at all levels of N when fungicide was not applied. The increase in lodging, as N rates increased, was observed only in the absence of fungicide, in both years. The occurrence of lodging took place late in the development of flax.

Nitrogen source and placement effects on stand density, pasmo severity, seed yield, and quality of no-till flax

“…In the current study, application of N fertilizer frequently increased stem and leaf pasmo. An increase in severity of pasmo disease with N application was also reported in a recently published study (Vera et al 2014). The form of N available to the host or pathogen is generally considered to have a more important impact on disease severity than the amount of N (Huber and Watson 1974).…”

Evaluation of Genomic Prediction for Pasmo Resistance in Flax

“…Flax (Linum usitatissimum L.) is an important food and fibre crop cultivated and grown in cooler regions of the world, such as Canada [1]. Pasmo, elicited by the fungus Septoria linicola , is one of the most widespread diseases of flax, causing reductions in seed and oil yield, as well as fibre quality and durability [2]. Developing resistant cultivars is the most viable and effective option to control this disease that has become widespread in all flax production areas of North America and other parts of the world.…”

Integrated agronomy for high yield and stable flax production in Canada

“…Increased yield due to fungicide application could have been due to a reduction in lodging due to reduced pasmo incidence, though little lodging was observed in this study. Pasmo caused lodging in other studies, which led to lower yields (Vera et al., 2012, 2014). It is also possible, and quite intriguing that the fungicide used in this study (pyraclostrobin + fluxapyroxad) contributes to greater yield in ways other than improved disease management.…”

“…Among all the combinations, fungicide application was found to be the primary determining factor for flax yield in this study as the top seven highest-yielding combinations all had fungicide applied to them (Table 3). An increase in crop yields due to fungicide application was identified in other studies (Bradley et al, 2007;Islam et al, 2021;Vera et al, 2014). The application of pyraclostrobin, in particular, has provided a 30% yield increase under high pasmo disease pressure in western Canada (IHARF, 2016).…”

“…Flax has been shown to be the least responsive crop to added N compared with many other oilseed crops and cereals (Hocking et al, 1997;Racz et al, 1965). In fact, other studies have reported a negative effect of increasing N fertilizer on crop yield due to the effect on flax emergence (Grant et al, 2016), increased pasmo disease incidence (Grant et al, 2016;Vera et al, 2014), and lodging (Grant et al, 1999;Pageau et al, 2006).…”