Coexistence of Related Pathogen Species on Arable Crops in Space and Time

Fitt, Bruce D.L.; Huang, Yongju; Bosch, Frank van den; West, Jonathan

doi:10.1146/annurev.phyto.44.070505.143417

Cited by 140 publications

(156 citation statements)

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“…Differences in averages were statistically analysed using one-way ANOVA. Leptosphaeria biglobosa 'canadensis' isolates caused significantly less internal stem infection at the crown of the stem than L. maculans isolates on all B. juncea lines and B. napus varieties tested (P < 0.001) ( (Fitt et al 2006b). In the present study, despite hyphae of L. biglobosa 'canadensis' and L. maculans growing intercellularly within the cotyledon and petiole, no L. biglobosa …”

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confidence: 99%

Identification ofLeptosphaeria biglobosa'canadensis' onBrassica junceastubble from northern New South Wales, Australia

Wouw

Thomas

Cozijnsen

et al. 2008

Austral. Plant Disease Notes

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Abstract. Leptosphaeria biglobosa 'canadensis' is reported for the first time in Australia. All 88 Leptosphaeria isolates cultured from Brassica juncea stubble from northern NSW were L. biglobosa 'canadensis' whilst all 55 isolates cultured from Victorian stubble of the same B. juncea lines were L. maculans. Both L. biglobosa 'canadensis' and L. maculans formed similar sized lesions on B. juncea cotyledons after 14 days. However, L. biglobosa 'canadensis' isolates colonised stems less effectively than L. maculans and consequently caused less crown cankering.The two Dothideomycetes, Leptosphaeria maculans and L. biglobosa, comprise a species complex associated with disease of crucifers including Brassica napus (canola, oilseed rape). Through the use of molecular techniques, L. biglobosa has been divided into six subclades, namely 'canadensis', 'occiaustralensis', 'brassicae', 'australiensis', 'erysimii' and 'thlaspii'. Leptosphaeria maculans has been divided into two subclades, 'brassicae' and 'lepidii ' (Mendes-Pereira et al. 2003;Voigt et al. 2005;Vincenot et al. 2008). In this paper we refer to L. maculans 'brassicae' as L. maculans.During infection of B. napus, L. maculans produces grey/ green large leaf lesions, followed by crown stem cankers. This disease, known as blackleg or Phoma stem canker, results in significant yield losses, particularly in Australia (Howlett 2004;Fitt et al. 2006a). In contrast, none of the subclades of L. biglobosa are reported to cause crown stem cankers. Leptosphaeria biglobosa 'brassicae' is the most common subclade. It is found in most canola growing areas with the exception of central Canada and Australia (Fitt et al. 2006a). These isolates cause small dark leaf lesions followed by pale brown stem lesions with a dark margin on the upper stem (known as Phoma or upper stem lesions) (West et al. 2002). In Australia, L. biglobosa 'australiensis' (cultured from B. napus) and more recently, L. biglobosa 'occiaustralensis' (cultured from B. napus and Raphanus raphanistrum (wild radish)) have been described in eastern and western Australia, respectively (Plummer et al. 1994;Vincenot et al. 2008).Blackleg is primarily controlled by breeding varieties with resistance to L. maculans (Delourme et al. 2006). Brassica juncea (Indian mustard) is generally more resistant to L. maculans than B. napus (Purwantara et al. 1998;Li et al. 2008). Additionally, B. juncea is more drought-tolerant and can be grown in regions with short, warm to hot growing seasons in which soil water supply is unreliable (Oram et al. 2005). In Canada, B. juncea has been grown as a condiment mustard crop for 20 years, specifically in the hotter, drier areas of western Canada. In 2002, B. juncea varieties were released that produced canola quality oils (Burton et al. 2004). Over the past 20 years in Australia, small acreages in regions including northern New South Wales have produced condiment mustard. Brassica juncea varieties that produce canola-quality oils were commercially released in 2007 .Since blackleg disease is...

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confidence: 99%

Identification ofLeptosphaeria biglobosa'canadensis' onBrassica junceastubble from northern New South Wales, Australia

Wouw

Thomas

Cozijnsen

et al. 2008

Austral. Plant Disease Notes

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“…Under a minimum tillage regime both L. maculans and L. biglobosa are able to survive and produce pseudothecia on crop debris on the soil surface. If stubble is left standing after harvest, the stem base has a higher water content than upper parts of the stem (Fitt et al 2006b). As moisture is required for pseudothecial maturation (Salam et al 2003;Toscano-Underwood et al 2003), therefore, ascospore release of the pathogen that has colonised the stem base will be earlier than that of the pathogen that has colonised the upper stem (Fitt et al 2006b).…”

Section: Discussionmentioning

confidence: 99%

“…If stubble is left standing after harvest, the stem base has a higher water content than upper parts of the stem (Fitt et al 2006b). As moisture is required for pseudothecial maturation (Salam et al 2003;Toscano-Underwood et al 2003), therefore, ascospore release of the pathogen that has colonised the stem base will be earlier than that of the pathogen that has colonised the upper stem (Fitt et al 2006b). On the other way, our recent experiments using oilseed rape varieties with Rlm7 resistance genes have shown their cultivation may contribute to the increase of the population of L. biglobosa, due to great efficiency in the control of disease symptoms caused by L. maculans.…”

Section: Discussionmentioning

confidence: 99%

Monitoring blackleg (Leptosphaeria spp.) ascospore release timing and quantity enables optimal fungicide application to improved oilseed rape yield and seed quality

Brachaczek¹,

Kaczmarek

Jędryczka

2016

Eur J Plant Pathol

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Stem canker is a damaging disease of winter oilseed rape, caused by ascomycetous fungi Leptosphaeria maculans and L. biglobosa. The initial source of plant infection is ascospores, formed in pseudothecia on stubble from the previous growing season. The aim of this work was to evaluate the effectiveness of fungicide treatments at different times of application in the autumn on quality and quantity of seed yield, in relation to the concentration of ascospores of L. maculans and L. biglobosa in the air. Field experiments were done in Lower Silesia, the region of intensive oilseed rape cultivation, located in south-west Poland. We have demonstrated that, in case of high disease pressure, fungicide treatment against stem canker was most efficient when done 4-11 days after the highest concentration of pathogen ascospores in air. The seed yield, oil and protein content increased by 17.7-18.8 %, 1.60-1.72 % and 0.8-0.9 % respectively. In low disease pressure the optimal spray time was more flexible, but the highest yield was always following the maximum ascospore release. In some cases it also coincided with the increase of oil, without adverse effect on protein content. Furthermore, it coincided with the increase of indole glucosinolates, such as glucobrassicine and 4-hydroxyglucobrassicine, and -besides one studied year -it was also connected with decreased amounts of alkenyl glucosinolates. Both Leptosphaeria species were present in air and in infected plants during their vegetation. The ratio between both species depended on seasons; L. maculans prevailed on leaves in the autumn, whereas L. biglobosa dominated on stems before harvest.

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“…Plant, animal, and human epidemics are influenced by the climate (Wint et al 2002;Fitt et al 2006;Thomson et al 2006), hence weather forecasts are already being used to guide control strategies for many important diseases worldwide (Garrett et al 2006). The possibility now exists to relate weather-based plant disease forecasts to recent climate change models, and hence predict the effects of climate change on where, which and by how much mycotoxins will be changed.…”

Section: Introductionmentioning

confidence: 99%

Ecological conditions affecting mycotoxin production in cereals: a review

Milani¹

2013

Vet. Med. - Czech

137

104

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Spoilage fungi are ubiquitous contaminants of cereals, pre-and post-harvest. These fungi can produce a wide range of secondary metabolites under ecological conditions which are conducive for growth. However, some of these secondary metabolites are toxic and have a significant impact if they enter the production and animal food chains. Prevention of mycotoxin contamination of feed and food raw materials is now considered more important than subsequent cure. The key ecological determinants pre-and post-harvest are water availability and temperature (climate). Accurate information is therefore needed on the impact of an association between these key factors, and it is necessary to understand which are marginal and which critical for germination and toxin production. There have only been a few studies where attempts have been made to integrate the available information on these factors in relation to different raw materials for feed and food processing, especially cereals. This review will examine the available information on the main climatic factors, i.e., water availability and temperature affecting mycotoxin production such as, aflatoxins, ochratoxins, fumonisins, zearalenone, deoxynivalenol and citrinin. This information is crucial for accurately focusing and monitoring key critical control points in the feed and food chain to optimise prevention strategies.

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Coexistence of Related Pathogen Species on Arable Crops in Space and Time

Cited by 140 publications

References 55 publications

Identification ofLeptosphaeria biglobosa'canadensis' onBrassica junceastubble from northern New South Wales, Australia

Identification ofLeptosphaeria biglobosa'canadensis' onBrassica junceastubble from northern New South Wales, Australia

Monitoring blackleg (Leptosphaeria spp.) ascospore release timing and quantity enables optimal fungicide application to improved oilseed rape yield and seed quality

Ecological conditions affecting mycotoxin production in cereals: a review

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