Distribution and prevalence of crown rot pathogens affecting wheat crops in southern Chile

Abstract

Crown rot pathogens are associated with higher losses for wheat crop farmers, but information about the distribution and prevalence of these pathogens in Chile is inadequate. Distribution and prevalence of wheat (Triticum aestivum L.) crown rot pathogens were examined in a survey of 48 commercial fields from December 2011 to February 2012 in southern Chile. These fields were located between Collipulli (37º56'00" S; 72°26'39" W) and Purranque (40º50'30" S; 73°22'03" W). Severity of crown rot disease was determined through visual assessment of the first internode of 20 tillers obtained from each field. Incidence of crown rot pathogens per field was determined by plating the 20 tillers on Petri plates with 20% potato dextrose agar amended with lactic acid (aPDA) medium. Resulting fungal colonies from monoxenic culture were identified by morphological or molecular-assisted identification. Severity of crown rot varied between 11.3% and 80% for individual fields. Culture plate analysis showed 72.2% of stems were infected with some fungus. Fusarium avenaceum, F. graminearum, and F. culmorum, pathogens associated with Fusarium crown rot disease were isolated from 13.5% of tillers. Gaeumannomyces graminis, causal agent of take-all disease in cereals, was isolated from 11.1% of culms. Phaeosphaeria sp., an endophyte and possibly a non-pathogenic fungus, was isolated from 13.9% of tillers. Pathogenic fungi such as Rhizoctonia spp. and Microdochium nivale, other saprophyte, and several unidentified non-sporulating fungi were isolated at frequencies lower than 3% of the total. Fusarium crown rot and take-all were the most prevalent and distributed crown rot diseases present in wheat crops in southern Chile.

Variability of Stem-Base Infestation and Coexistence of Fusarium spp. Causing Crown Rot of Winter Wheat in Serbia

“…In the study of Tyburski et al (2014) F. oxysporum originated from 3.8% isolates of stem-base of wheat collected in BBCH 83–87. Other authors reported lower percent of F. oxysporum isolated from the stem-base in dough grain stage (0.5%) or in later growth stages (2.1%) (Moya-Elizondo et al, 2015; Xu et al, 2018). In addition, F. oxysporum is mainly reported as saprophyte or as the species with low pathogenic potentials (Moya-Elizondo et al, 2015).…”

“…Other authors reported lower percent of F. oxysporum isolated from the stem-base in dough grain stage (0.5%) or in later growth stages (2.1%) (Moya-Elizondo et al, 2015; Xu et al, 2018). In addition, F. oxysporum is mainly reported as saprophyte or as the species with low pathogenic potentials (Moya-Elizondo et al, 2015). Frequency of F. oxysporum isolated from stem-base in this study indicated that in the years which are not favorable for crown rot infection, F. oxysporum could have impact on wheat production through both pathogenic and saprophytic potentials.…”

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).…”

Screening and Characterization of Potentially Suppressive Soils against Gaeumannomyces graminis under Extensive Wheat Cropping by Chilean Indigenous Communities

“…The southern region of Chile produces around 85% of cereals, where 40% is wheat ( Triticum aestivum L.; ODEPA, 2016 ). However, wheat production is frequently reduced by the incidence of “take-all” disease, which is caused by the soil-borne pathogen Gaeumannomyces graminis var tritici (Ggt; Andrade et al, 2011 ), causing the highest wheat crop losses in Chile (Moya-Elizondo et al, 2015 ). Soil-borne pathogen incidence in cereal cropping is difficult to control due to their natural persistence in soils and the inefficiency of chemical controls (De Coninck et al, 2015 ); thus, biological control becomes a very promising alternative to prevent soil diseases.…”