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

Abstract

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

Long-term no-till: A major driver of fungal communities in dryland wheat cropping systems

“…However, Microdochium bolleyi was of relatively high abundance, and increased in the no-till treatments across all locations and years. This taxon is considered to be a weak parasite of wheat roots [ 40 ], a potential biocontrol agent against other root pathogens [ 41 ] and has been shown in another study to be more common in no-till, based on isolation from wheat roots [ 42 ]. We also detected Hymenula cerealis , also known as Cephalosporium gramineum .…”

Spatial and Temporal Variation of Cultivable Communities of Co-occurring Endophytes and Pathogens in Wheat

“…Early species were dominated by B. subtilis , a species known to grow in soil and in the rhizosphere of many plants (Earl et al, 2008 ). They included soil-borne fungal pathogens, causing devastating diseases on a broad host range, such as R. solani (Lemańczyk, 2012 ), abundantly found in European agricultural soils (Goll et al, 2014 ) , S. sclerotiorum (Bolton et al, 2006 ), and B. cinerea (Dean et al, 2012 ) or considered as minor pathogens, such as M. bolleyi , commonly found on cereals roots (Kirk and Deacon, 1987a ; Fernandez and Holzgang, 2009 ). M. graminicola , the causal agent of the S. tritici blotch, an important foliar disease on winter wheat in Europe (Miedaner et al, 2013 ), was mostly isolated at heading although its cycle extends until wheat maturity.…”

Diversity of theFusariumpathogens associated with crown rot in the Huanghuai wheat‐growing region of China

“…Fusarium crown rot (FCR) is one of the most destructive soil-/ residue-borne diseases of wheat in many countries, including Australia (Wildermuth et al, 1997;Backhouse et al, 2004), South Africa (Van WyK et al, 1987), the countries and regions around the Mediterranean (Balmas, 1994;Burgess et al, 2001;Tunali et al, 2008;Shikur Gebremariam et al, 2018), Iran (Saremi et al, 2007), Chile (Moya-Elizondo et al, 2015), Spain (Agusti-Brisach et al, 2018), North America (Smiley and Patterson, 1996;Fernandez and Zentner, 2005;Fernandez and Holzgang, 2009;Moya-Elizondo et al, 2011) and China (Li et al, 2012;Zhang et al, 2015). Symptoms of FCR include seedling blight (Dyer et al, 2009), brown discoloration of the lower stems with an occasional pink coloration of the nodes or stems under the leaf sheaths, and whiteheads at maturity (Wallwork, 2000;Hollaway and Exell, 2010).…”