Fusarium populations in roots of oilseed and pulse crops grown in eastern Saskatchewan

Abstract

Fernandez, M. R. 2007. Fusarium populations in roots of oilseed and pulse crops in eastern Saskatchewan. Can. J. Plant Sci. 87: 945-952. Roots of canola, flax, lentil and pea crops, commonly grown in rotation with wheat and barley on the Canadian Prairies, were sampled for extent of discolouration and associated fungal populations in eastern Saskatchewan, in 2000 and 2001. Fusarium was the genus most commonly isolated from pulse crops, particularly lentil, and one of the most common genera isolated from oilseed crops. The discolouration severity of pulse and flax roots was associated with Fusarium spp., and that of canola with Alternaria spp. Cochliobolus sativus and other commonly isolated species appeared to be present in roots as weak pathogens or saprophytes. Most of the Fusarium spp. have also been isolated from cereal crops affected by crown/root rot or fusarium head blight (FHB) in the province, although at different relative levels. These included F. avenaceum, the most commonly isolated species, and F. culmorum and F. graminearum, which were among the least prevalent species. This is the first report of isolation of F. graminearum from roots of field-grown pulse and oilseed crops in western Canada. For most crops, the number of tillage operations in the previous 3 yr was positively associated with the occurrence of C. sativus and negatively associated with that of F. avenaceum. Our results suggest that the noncereal crops examined would help to maintain or increase Fusarium inoculum in plant tissue, which might contribute to the development of crown/root rot and FHB in subsequently grown cereal crops, especially under conditions more conducive to disease development. This would especially be the case for pulse crops, which had the highest levels of root discolouration, and F. avenaceum. However, noncereal crops would not be significant reservoirs of inoculum of F. culmorum or F. graminearum.

Impact of agronomic practices on populations of Fusarium and other fungi in cereal and noncereal crop residues on the Canadian Prairies

“…were commonly isolated from all residue types. Overall, the relative percentage isolation values of the Fusarium species in crop residues were similar to those reported by Fernandez et al (2007a,b) for discoloured subcrown internodes of common wheat and barley, and for roots of noncereal crops (Fernandez, 2007) sampled in the same region. Our observations also agree with previous reports of the presence of the most important Fusarium spp.…”

“…Noncereal residues appeared to be better substrates than cereal residues for the growth and survival of F. avenaceum than for other Fusarium species 10-11 months after harvest. The higher PO and MPI of F. avenaceum from noncereal than cereal residues is consistent with the higher percentage isolation of this fungus from underground tissue of noncereal, especially pulses, than of cereal crops (Fernandez, 2007;Fernandez et al, 2007a,b). In our current study, F. avenaceum was isolated as frequently from flax as from pulse residues in contrast to the report on roots of the same plant species where F. avenaceum was reported at higher levels in pulse roots than in canola or flax roots (Fernandez, 2007).…”

“…The more frequent isolation of F. equiseti from barley than other cereal residues also agrees with previous observations on stubble (Sturz and Bernier, 1987a) and living subcrown internode tissue (Fernandez et al, 2007a,b). The observation that these two fungi were frequently isolated from ground and/or underground tissue of living cereal and noncereal crops sampled close to maturity (Fernandez and Jefferson, 2004;Fernandez, 2007;Fernandez et al, 2007a,b) suggests that they may have been among the primary colonizers of plant tissue at senescence.…”

Effectiveness of fungicide seed treatments for preventing seed-to-seedling transmission of Fusarium graminearum under controlled-environment conditions

“…This is especially the case for F. graminearum, which is the most important FHB pathogen in wheatgrowing areas of North America. Fusarium avenaceum, one of the most important FHB pathogens in the prairies (Turkington et al , 2004Pearse et al 2007b;Clear and Patrick 2008), is also a commonly found pathogen in roots, crowns and residues of a wide range of plant species (Fernandez 2007;Fernandez et al 2007aFernandez et al , b, 2008. Fungicide treatments effective against this pathogen, whether as seed-borne or soil-borne inoculum, would be of value in preventing seedling blight in cereal crops, especially when these are grown in rotation with noncereal crops, particularly pulses, which are most susceptible to F. avenaceum (Fernandez 2007).…”

Assessing Effects of Climatic Change, Region and Agronomic Practices on Leaf Spotting of Bread and Durum Wheat in the Western Canadian Prairies, from 2001 to 2012

“…In addition to barley (Hordeum vulgare L.), a known host of C. sativus, Duczek et al (1996) observed that this pathogen sporulated on crowns of other annual cereals, wheatgrass, and other forage grasses, suggesting that sporulation on these crops may maintain or increase its inoculum levels in soil. Non-cereal crops, such as oilseeds and pulses, have also been shown to harbor C. sativus in crowns (Duczek et al, 1996) and roots (Fernandez, 2007). It is expected that some of the current popular agronomic practices, such as reduced tillage, rotation with non-cereals and lower frequency of summerfallow, would contribute to lower levels of C. sativus in leaves and roots/crowns; however, these practices would help increase the presence of Fusarium pathogens in the latter (Fernandez et al, , 2009.…”