Co-occurrence of an<i>Aphanomyces</i>sp. and<i>Phytopththora clandestina</i>in subterranean clover pastures in the high rainfall areas of the lower south-west of Western Australia

Ma, Xuanli; Li, Hua; O'Rourke, Tiernan A.; Sivasithamparam, Krishnapillai; Barbetti, Martin J.

doi:10.1071/ap07086

Cited by 16 publications

(18 citation statements)

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“…The important oomycete soilborne pathogens on subterranean clover include Aphanomyces trifolii , various Pythium species, particularly Pythium irregulare , Phytophthora clandestina and Rhizoctonia solani (Wong et al ., ,; Barbetti et al ., ,, , ; You et al ., , ; Ma et al ., ; O'Rourke et al ., ; Nichols et al ., ; You & Barbetti, ). Recently, Foster et al .…”

Section: Introductionmentioning

confidence: 98%

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Critical factors driving aphanomyces damping‐off and root disease in clover revealed and explained using linear and generalized linear models and boosted regression trees

et al. 2018

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Subterranean clover (Trifolium subterraneum) is an important forage legume in Mediterranean regions worldwide. Aphanomyces damping‐off and root disease (Aphanomyces trifolii) poses significant threat to its persistence and productivity. Studies were conducted to define how environmental explanatory variables (temperature, soil type, moisture, nutrition) and variety influence disease severity and consequent forage productivity and persistence. Relationships were modelled using linear and generalized linear models and boosted regression trees. Linear modelling highlighted complex relationships between environmental variables and each dependent variable (emergence, tap and lateral root disease, dry shoot and root weight). All environmental variables produced significant interaction and/or main effects within each dependent variable. Boosted regression trees supported the complex nature of relationships in linear models, with temperature and either soil or variety most, and nutrition least, influential. Heat maps showed more disease for low temperatures. Least tap root disease was under high temperatures, while least lateral root disease was under medium or high temperatures, low moisture, and in sand‐based soil. These are the first studies using modelling approaches to reveal the complexities of how fluctuating soil temperature, moisture and nutrition conditions, and soil type and variety, determine aphanomyces damping‐off and root disease severity and resultant adverse impacts on forage legume productivity and persistence. Outcomes are widely applicable across soilborne oomycete pathogens of forage legumes. Studies highlighted how warming temperatures and drying climate associated with climate change should reduce future impact and importance of this and other soilborne oomycete diseases of forage legumes favoured by cold temperatures and wet and waterlogged conditions.

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Section: Introductionmentioning

confidence: 98%

“…In the interim, when Ma et al . () surveyed the incidence and distribution of an Aphanomyces species in forages within the high rainfall areas (>700 mm) of southwest Western Australia in 2007, they found an Aphanomyces species at 23 locations. In eastern Australia, Greenhalgh et al .…”

Section: Introductionmentioning

confidence: 99%

Critical factors driving aphanomyces damping‐off and root disease in clover revealed and explained using linear and generalized linear models and boosted regression trees

et al. 2018

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“…This experiment was conducted in 2007 to determine the virulence of 23 isolates of A. trifolii collected in 2007, from which six isolates were from two field sites at Bow Bridge, three isolates from Mt Barker, nine isolates from Porongurup, two isolates from Scottsdale and four isolates from Tingledale, southwest Western Australia (see Fig. of Ma et al ., for details of locations). The experiment was conducted in a controlled environment room where the air temperature was maintained at 18/13°C (day/night), with a 12/12 h photoperiod and a light intensity of 470 μ mol m −2 s −1 .…”

Section: Methodsmentioning

confidence: 99%

“…Subsequently, Ma et al . () surveyed the incidence and geographical distribution of an Aphanomyces sp. and P .…”

Section: Introductionmentioning

confidence: 99%

Host resistances to Aphanomyces trifolii root rot of subterranean clover: first opportunity to successfully manage this severe pasture disease

et al. 2015

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Subterranean clover (Trifolium subterraneum) is an important pasture legume in Australia (29 million ha) and elsewhere. However, severe pasture decline occurs in association with several root pathogens, including Aphanomyces trifolii, that has been misidentified for decades as A. euteiches until recently confirmed as A. trifolii. A series of controlled environment experiments was undertaken to identify host resistance to A. trifolii in subterranean clover and to compare virulence and phylogeny of isolates. In experiment 1, Dalkeith, Bacchus Marsh, Riverina and Yarloop were the most resistant of 38 cultivars with a percentage disease index (PDI) ≤10 for both tap and lateral roots. Experiment 2 confirmed resistance of Yarloop, but a change in some relative varietal resistances suggested physiological specialization among A. trifolii isolates. Experiment 3 confirmed extensive variation in virulence and physiological specialization across 23 isolates of A. trifolii, with three distinct clades, two of which were distinct from isolates collected previously. Experiment 4 identified host resistance(s) effective against a mixture of 20 A. trifolii isolates, but the most resistant cultivars (Antas, Uniwager, Leura) still showed significant disease. This is the first study to show physiological specialization in A. trifolii and to identify host resistance. This study defines A. trifolii as a significant but largely unknown contributor to severe root disease of subterranean clover in southern Australia. Finally, development and calibration of a new soil commercial DNA test not only enables field quantification of the disease, but development of appropriate breeding, selection and farm management strategies to reduce its impact.

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“…The infective propagules are asexual biflagellate zoospores, which are produced in sporangia and spread via aquatic media, interstitial soil moisture, raindrop splashes and wind-driven rain. Consequently, damages often occur under wet climatic conditions and poorly drained soils (Sanogo 2006, Xie et al 1999, Rhoades et al 2003, Ma et al 2008. Some of the most devastating Phytophthora diseases occur in periodically wet and dry environments by synergistic interaction between fine root losses by Phytophthora and severe droughts (Jung et al 1996, Balci & Halmschlager 2003, Newhook & Podger 1972.…”

Section: Typical Features Of Phytophthoramentioning

confidence: 99%

Phytophthora in Finnish nurseries

Rytkönen¹

2011

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International trade and travel have facilitated the spread of harmful organisms around the world. Human-mediated movement of plants and plant products is now generally accepted to be the primary mode of introduction of pathogens and pests. Species of Phytophthora, a genus of plant pathogens, are commonly spread in this way and have caused severe epidemics in silviculture, horticulture and natural systems all over the world.The objective of the study was to gather information on the occurrence of Phytophthora spp. in Finnish nurseries. Furthermore, the aim was to produce information for risk assessments for these Phytophthora spp. and establish molecular means for their detection. Phytophthora cactorum was found to persist in natural waterbodies and results suggest that irrigation water might be a source of inoculum for the disease in nurseries. In addition to P. cactorum, isolates from ornamental Rhododendron in nurseries yielded three species new to Finland: P. ramorum, P. plurivora and P. pini. The only species with quarantine status, P. ramorum, was able to persist in the nursery in spite of an annual European Commission sanitation protocol. Phytophthora plurivora and the closely related P. pini had more hosts among Nordic tree species and other plants abundant in Finnish nurseries and forest ecosystems. They were also found to have higher infectivity rates compared to P. ramorum and P. cactorum. All four species survived two weeks in -5 °C , and thus soil survival of these Phytophthoras in Finland is likely under current climatic conditions.The most common tree species in Finnish nurseries, Picea abies, was highly susceptible to P. plurivora and P. pini in pathogenicity trials. In a histological examination of P. abies shoot tissues inoculated with P. plurivora zoospores, fast necrotrophic growth was observed in nearly all tissues of the fresh shoot. The production of propagules in P. abies shoot tissue was only weakly indicated.In this study, a PCR-DGGE technique was developed for simultaneous detection and identification of Phytophthora spp. It reliably detected Phytophthora in plant tissues and could discriminate most test species as well as indicate instances of multiple-species infections. It proved to be a useful detection and identification tool either applied alone or in concert with traditional isolation culture techniques. The limitations of the method are also discussed.In conclusion, all of the introduced species of Phytophthora had properties that promote a high risk of establishment and spread in Finland. The efficient transport of Phytophthora via commercial traffic and favorable conditions due to expected climate change will increase the incidence and establishment of Phytophthora in new areas. Thus, it is probable that pathogens of this genus will be introduced and become established in Finland and other Nordic countries unless efficient phytosanitary control becomes standard practice in the international plant trade.Keywords: Phytophthora, pathogenicity, survival, molecular detectio...

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Co-occurrence of anAphanomycessp. andPhytopththora clandestinain subterranean clover pastures in the high rainfall areas of the lower south-west of Western Australia

Cited by 16 publications

References 16 publications

Critical factors driving aphanomyces damping‐off and root disease in clover revealed and explained using linear and generalized linear models and boosted regression trees

Critical factors driving aphanomyces damping‐off and root disease in clover revealed and explained using linear and generalized linear models and boosted regression trees

Host resistances to Aphanomyces trifolii root rot of subterranean clover: first opportunity to successfully manage this severe pasture disease

Phytophthora in Finnish nurseries

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