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

Discoloration of subcrown internodes (SIs) and crowns/lower culms (CLCs) of 87 oat crops across Saskatchewan in 1998-1999 and of SIs in 31 oat crops in eastern Saskatchewan (Black Soil Zone) in 2000-2001 was evaluated. Fungi in discolored tissue were isolated, identified and quantified, and the percentage of fields from which each fungus was isolated at least once (occurrence) and their relative percentage isolation levels were determined. In the 1998-1999 survey, discoloration severity varied more between years than among soil zones. Fusarium was the most common genus present, and F. culmorum the most common species. This was followed by F. equiseti, Microdochium bolleyi, Cochliobolus sativus, and F. avenaceum. Levels of C. sativus were lower in oat than those reported for wheat and barley in parallel province-wide surveys. Percentage isolation of F. culmorum was higher in the Brown than in the Black/Dark Gray Soil Zone, whereas the percentage occurrence of F. avenaceum was highest in the Black/Dark Gray Soil Zone. In 2000-2001, in eastern Saskatchewan, M. bolleyi, F. avenaceum, C. sativus, F. equiseti, Alternaria spp., and Pyrenophora avenae were the most common fungi isolated from discolored oat SIs. Similar to reports from wheat and barley, F. graminearum was isolated from SIs in eastern Saskatchewan at low levels. For the most part, neither previous crop nor tillage system affected fungal levels in SIs. P. avenae levels increased when the previous crop was another oat rather than wheat or barley. We conclude that oat could maintain or increase inoculum levels of Fusarium pathogens that cause damage to cereal crops in Saskatchewan. This is supported by results from a crop residue study in eastern Saskatchewan that showed that F. avenaceum, F. culmorum and F. graminearum occurred at similar or higher levels in oat fields than in fields of wheat or barley. Key words: Oat, root rot, crown rot, crop rotation, tillage system, Fusarium head blight, Fusarium spp., Fusarium avenaceum, Fusarium culmorum, Fusarium graminearum, Cochliobolus sativus, Pyrenophora avenae

Section: Oat Study In Eastern Saskatchewan (2000 á 2001)supporting

confidence: 57%

Fungal populations in subcrown internodes and crowns of oat crops in Saskatchewan

Fernandez¹,

Holzgang²

2009

“…This partly confirms the results of the multivariate analysis, where the Cs vector was associated the most with summerfallow in the previous year, or a cereal crop alternated with summerfallow in the previous 2 yr. Gilbert and Woods (2001) reported that Cs was isolated more frequently from wheat grown in Manitoba after a noncereal than a cereal crop but it is not known what effect the previous 2-yr cropping history had on this pathogen in their study. The relative high levels of Cs in wheat grown after 2 yr of noncereal crops might be partly explained by the ability of this fungus to sporulate well in old cereal residues, and grow on residues of oilseed and pulse crops (Duczek et al 1996(Duczek et al , 1999Fernandez et al 2008).…”

Section: Effect Of Seeding Rate On Ls Severity and Pathogensmentioning

confidence: 99%

Impacts of agronomic practices on the leaf spotting complex of common wheat in eastern Saskatchewan

Fernandez¹,

Pearse²,

Holzgang³

et al. 2009

Self Cite

. 2009. Impacts of agronomic practices on the leaf spotting complex of common wheat in eastern Saskatchewan. Can. J. Plant Sci. 89: 717Á730. A survey of commercial common wheat crops was conducted in eastern Saskatchewan (2000Saskatchewan ( to 2002 to determine the effects of agronomic practices on the leaf spot (LS) disease complex and causal pathogens, and to determine the impact of LS on crop productivity. Leaf spots had a negative impact on grain yield, but did not affect market grade consistently. There was little effect of agronomic practices on LS severity, but cropping sequence and tillage system affected the mean percentage fungal isolation (MPI), whereas only tillage affected the percentage fungal occurrence. A previous noncereal crop, which had in most cases been preceded by a cereal, resulted in a higher MPI of Pyrenophora tritici-repentis (Ptr), the most common pathogen, and a lower MPI of the septoria leaf blotch fungi Mycosphaerella graminicola (Mg) and Phaeosphaeria nodorum (Pn). Levels of Ptr tended to be lower after 2 yr of noncereals, grown mostly under zero tillage. Overall, the MPI of Ptr increased with a reduction in tillage, being most common under zero tillage, whereas the septoria leaf blotch fungi were least common under zero tillage, and Cochliobolus sativus (Cs) was most prevalent under conventional tillage. The highest MPI of Cs occurred after summerfallow under conventional tillage. Tillage effects also varied with cropping sequence, being most pronounced after another cereal. Pyrenophora tritici-repentis was also associated with recommended or high seeding rates and with high N fertilizer input, although these factors might have been confounded by tillage system and cropping sequence, respectively. Overall, our findings indicate that in eastern Saskatchewan Ptr infection of common wheat prevailed in high-yielding and high N systems that included previously grown noncereals grown under zero tillage and seeded at recommended to high rates, whereas Pn, Mg and Cs occurred the most in lower-yielding and lower N systems preceded by another cereal crop or summerfallow under conventional tillage. However, LS severity was not significantly or consistently affected by any agronomic practice, which was attributed to the presence of all the most common LS pathogens in the region and years this study was conducted.Key words: Wheat, oilseed, pulse, summerfallow, leaf spots, tan spot Fernandez, M. R., Pearse, P. G., Holzgang, G., Basnyat, P. et Zentner, R. P. 2009. Impact des pratiques culturales sur la septoriose du ble´dans l'est de la Saskatchewan. Can. J. Plant Sci. 89: 717Á730. Les auteurs ont entrepris une enqueˆte sur le ble´cultive´dans l'est de la Saskatchewan (2000 a`2002) en vue de pre´ciser l'incidence des pratiques agricoles sur la septoriose et sur les agents pathoge`nes qui en sont la cause, ainsi que pour de´terminer l'impact de cette maladie sur le rendement des cultures. La septoriose diminue le rendement du ble´, mais n'a pas d'impact cohe´rent sur sa qualiteć ommerciale. Les ...

“…The primary source of inoculum for infection of cereal crops is infected residue on the ground (Sutton 1982;Fernandez et al 2008). Seed-to-seedling transmission of F. graminearum was demonstrated by Duthie and Hall (1987), Klein and Burgess (1987), and Halfon-Meiri et al (1979).…”

mentioning

confidence: 99%

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

Fernandez¹,

Turkington²,

May³

2009

Fusarium head blight (FHB) is well established in the eastern prairies, but for the most part it has been absent from western regions, especially under dryland conditions. This has been largely attributed to dry and hot conditions during some years, and the limited occurrence of F. graminearum in the western prairies. It is of importance to prevent the movement of F. graminearum, the most important FHB pathogen in North America, to areas where this pathogen is not commonly found. Three controlled-environment studies, using different Fusarium-infected common and durum wheat seed lots, were conducted to determine the effectiveness of currently registered fungicide seed treatments in improving seedling emergence and plant development, and preventing the growth of F. graminearum from infected seed to plant tissue. Fungicide treatments improved seedling emergence from the most infected seed over the untreated infected control, but most treatments did not improve emergence in the other experiments. Plant growth in the fungicide treatments was either similar to or slower than in the untreated controls. Fusarium graminearum was isolated from discoloured tissue in all treatments and was generally more common in crowns than in subcrown internodes. No fungicide treatment reduced discolouration of plant tissue or percentage isolation of F. graminearum or other Fusarium spp. consistently. We conclude that while currently registered seed treatments might be effective in improving seedling emergence in some infected wheat seed lots, they do not prevent the growth of F. graminearum from seeds to plant tissue. For the western prairies, the use of fungicide seed treatments as a strategy in the prevention of spread of FHB would require that they be effective primarily against F. graminearum. Performance of fungicide seed treatments against Fusarium-infected wheat seed should also be determined under typical growing conditions across the western prairies.Key words: Seed treatments, fungicides, wheat, root rot, crown rot, Fusarium graminearum, Fusarium avenaceum