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1.
Detection of Colletotrichum coccodes and Helminthosporium solani in soils by bioassay 总被引：1，自引：0，他引：1
The sensitivity of a bioassay in detecting soil inoculum of Colletotrichum coccodes and Helminthosporium solani was examined using potato minitubers and microplants. Tests were conducted on soils which were collected from fields in which the interval after a previous potato crop differed, and which were also artificially infested with conidia or microsclerotia. For C. coccodes , determining plant infection based on the occurrence of infected roots after 9–12 weeks was a sensitive method for detecting and quantifying the amount of inoculum in soil. Infestations of less than 0·4 microsclerotia per g soil were detected in artificially infested soils. A semiselective medium, developed for isolating C. gloeosporioides from pepper, detected soil infestations by C. coccodes as low as nine conidia or one microsclerotium per g soil in artificially infested soil. For H. solani , infection on minitubers was a sensitive measure, with soil inoculum of fewer than 10 conidia per g soil being detected. Soil infestation could be quantified by assessing the percentage surface area of minitubers covered by sporulating lesions, which was strongly related to the amount of soil infestation. The results of these bioassay tests were compared with published results for real-time quantitative PCR assays on the same soils. The two methods were in good agreement in artificially infested soils, but the bioassay appeared to be more sensitive with naturally infested soils. 相似文献
2.
Sjolund M. Jennifer Arnsdorf Yvonne M. Carnegie Mairi Fornefeld Eva Will Torsten 《植物病害和植物保护杂志》2019,126(1):89-92
Journal of Plant Diseases and Protection - Psyllids are small, phloem-feeding insects. Several species are vectors of economically important pathogens, such as ‘Candidatus Liberibacter... 相似文献
3.
A. K. Lees J. A. Stewart J. S. Lynott S. F. Carnegie H. Campbell A. M. I. Roberts 《Potato Research》2012,55(2):125-134
As a result of recent changes in the Phytophthora infestans population in Great Britain, in particular the dominance of one genotype (13_A2) and the possible implications of this change
on host resistance ratings, a coordinated programme of testing between SASA and JHI was initiated. Over 3 years of trials
(2008–2010), 49 existing cultivars with published resistance ratings of 5 or greater on a 1–9 scale of increasing resistance,
42 new cultivars and a range of appropriate control cultivars were assessed using an isolate of the 13_A2 genotype of P. infestans. The mean resistance rating of 62% of the 49 existing cultivars was reduced by more than the maximum 5% LSD of 1.9. For some
cultivars (e.g. Lady Balfour and Stirling), changes in resistance rating were specifically associated with the use of the
13_A2 genotype to inoculate the trials from 2008 onwards. The majority of the 42 new cultivars tested were susceptible to
the 13_A2 genotype isolate, scoring 4 or less. However, cultivars with useful resistance were also identified with seven scoring
6 or 7. Published resistance ratings have been revised as a result of this study. 相似文献
4.
Genetic diversity of the myrtle rust pathogen (Austropuccinia psidii) in the Americas and Hawaii: Global implications for invasive threat assessments 
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下载免费PDF全文 J. E. Stewart A. L. Ross‐Davis R. N. Graҫa A. C. Alfenas T. L. Peever J. W. Hanna J. Y. Uchida R. D. Hauff C. Y. Kadooka M.‐S. Kim P. G. Cannon S. Namba S. Simeto C. A. Pérez M. B. Rayamajhi D. J. Lodge M. Arguedas R. Medel‐Ortiz M. A. López‐Ramirez P. Tennant M. Glen P. S. Machado A. R. McTaggart A. J. Carnegie N. B. Klopfenstein 《Forest Pathology》2018,48(1)
Since the myrtle rust pathogen (Austropuccinia psidii) was first reported (as Puccinia psidii) in Brazil on guava (Psidium guajava) in 1884, it has been found infecting diverse myrtaceous species. Because A. psidii has recently spread rapidly worldwide with an extensive host range, genetic and genotypic diversities were evaluated within and among A. psidii populations in its putative native range and other areas of myrtle rust emergence in the Americas and Hawaii. Microsatellite markers revealed several unique multilocus genotypes (MLGs), which grouped isolates into nine distinct genetic clusters [C1–C9 comprising C1: from diverse hosts from Costa Rica, Jamaica, Mexico, Puerto Rico, and USA‐Hawaii, and USA‐California; C2: from eucalypts (Eucalyptus spp.) in Brazil/Uruguay and rose apple (Syzygium jambos) in Brazil; C3: from eucalypts in Brazil; C4: from diverse hosts in USA‐Florida; C5: from Java plum (Syzygium cumini) in Brazil; C6: from guava and Brazilian guava (Psidium guineense) in Brazil; C7: from pitanga (Eugenia uniflora) in Brazil; C8: from allspice (Pimenta dioica) in Jamaica and sweet flower (Myrrhinium atropurpureum) in Uruguay; C9: from jabuticaba (Myrciaria cauliflora) in Brazil]. The C1 cluster, which included a single MLG infecting diverse host in many geographic regions, and the closely related C4 cluster are considered as a “Pandemic biotype,” associated with myrtle rust emergence in Central America, the Caribbean, USA‐Florida, USA‐Hawaii, Australia, China‐Hainan, New Caledonia, Indonesia and Colombia. Based on 19 bioclimatic variables and documented occurrences of A. psidii contrasted with reduced sets of specific genetic clusters (subnetworks, considered as biotypes), maximum entropy bioclimatic modelling was used to predict geographic locations with suitable climate for A. psidii which are at risk from invasion. The genetic diversity of A. psidii throughout the Americas and Hawaii demonstrates the importance of recognizing biotypes when assessing the invasive threats posed by A. psidii around the globe. 相似文献
5.
Infection of potato plants by viruses causing mosaic symptoms may result in a reduction in crop yield, depending on severity
of symptoms and incidence. In 2004 and 2007, an investigation was undertaken to examine the relationship between plants with
mosaic symptoms and the occurrence of growth cracking in daughter tubers. Samples of pairs of plants affected by mosaic symptoms
and plants with no symptoms were collected from nine potato crops, of which seven were cv. Estima, containing at least 20%
mosaic-affected plants. Growth cracking was more prevalent on mosaic-affected plants of cv. Estima than on plants with no
symptoms. The incidence of growth cracking was much greater on plants showing mosaic symptoms caused by a mixed infection
of Potato virus A and Potato virus V together than on symptomatic plants infected by either virus alone. The presence of virus in plants with no symptoms did
not affect the incidence of tubers affected by cracking. In a crop of the advanced selection Blue Tzar, plants with mosaic
symptoms caused by Potato virus Y
N
produced more tubers with cracking than plants with no symptoms. Growth cracking did not occur in the one sampled crop of
cv. Désirée infected by Potato virus A. 相似文献
6.
The Damariscotta River estuary is a center of oyster culture in Maine, yet the comparative performance of flat oysters Ostrea edulis at different locations in this now Bonamia ostreae -enzootic estuary has not been assessed. Juvenile O. edulis were deployed in July 1997 among replicate floating trays at one estuarine (Little Point) and one marine site (Lowes Cove), and growth, mortality, and B. ostreae prevalence were compared through December 1999. Growth was faster at Little Point though oysters at both locations reached market size in less than three full growing seasons. Mortality was similar between locations except following a June 1998 rain event that decreased salinity more precipitously at Little Point. Cumulative mortality was greater at Little Point (45.8%) than Lowes Cove (26.7%). Surprisingly, B. ostreae was observed in only a single oyster from Little Point in May 1998. These data indicate that flat oysters in Maine may grow well across a wide range of environments, yet may demonstrate better survival at marine sites where salinity fluctuations are less extreme. While B. ostreae is likely still a threat, selection of sites where rapid growth to market size is possible may reduce its impact. 相似文献
7.
Schoof VA Jack KM Carnegie SD 《Folia primatologica; international journal of primatology》2011,82(6):299-307
We examined fecal androgen and cortisol levels in three adult male white-faced capuchin monkeys (Cebus capucinus) before and after a non-aggressive rank increase in one habituated group residing in the Santa Rosa Sector of the área de Conservación Guanacaste, Costa Rica. Fecal samples (n = 116) were collected opportunistically between July 2006 and July 2007. Alpha males had higher mean androgen levels than subordinates, and acquisition of the alpha position was linked to an immediate increase in mean androgens. Cortisol levels also increased in the alpha male after acquisition of his new rank, though this increase was delayed relative to the change in rank. These results indicate that, during a non-aggressive rank change, androgen and cortisol levels in male white-faced capuchins are physiological responses to dominance rank, rather than precursors that facilitate rank acquisition. 相似文献
8.
Global movement and population biology of Mycosphaerella nubilosa infecting leaves of cold-tolerant Eucalyptus globulus and E. nitens 总被引：1，自引：0，他引：1
G. C. Hunter † N. A. van der Merwe T. I. Burgess A. J. Carnegie B. D. Wingfield P. W. Crous M. J. Wingfield 《Plant pathology》2008,57(2):235-242
Using 10 polymorphic DNA-based microsatellite markers, the genetic diversity of eight Mycosphaerella nubilosa populations from Eucalyptus , comprising 497 isolates from five different countries, was studies using a hierarchical sampling regime. Mycosphaerella nubilosa from eastern Australia (New South Wales) had higher gene (0·506) and genotypic (76%) diversity than other populations, supporting the view that this represents the origin of the pathogen. It was also evident that M. nubilosa populations from Europe and Tanzania were clonal, with the same multilocus haplotypes occurring in South Africa, but being absent in Australia. This suggests that M. nubilosa may have been introduced into Europe via Africa, with a pathway of gene flow from Australia to South Africa, further into Africa and finally to Europe. 相似文献
9.
Summary Between 1976 and 1981, healthy seed tubers were kept in five stores used for holding virustested stem cutting stocks. The
incidence ofPolyscytalum pustulans (skin spot) andPhoma exigua var.foveata (gangrene) was assessed after four months storage. The tubers were planted, often after various treatments, and the incidence
of the pathogens on their progeny tubers assessed after harvesting and further storage.
Seed tuber contamination byP. pustulans varied with the store and the differences were reflected in the incidences of contamination on their progeny tubers. Progeny
tuber contamination byP. pustulans was not affected by fumigation of the seed tuber with 2-aminobutane but was reduced by dipping seed tubers just prior to
planting in either a surface disinfectant or thiabendazole.
Seed and progeny tuber contamination byP. exigua var.foveata was not affected by storage site or by chemical treatment just prior to planting.
Zusammenfassung Zwischen 1976 und 1981 wurden gesunde Pflanzknollen in fünf L?gern gehalten, die zum Aufbewahren virusgetesteter ‘stem cutting”-Best?nde dienten. Nach viermonatiger Lagerung wurde das Auftreten vonPolyscytalum pustulans (Tüpfelfleckenkrankheit) undPhoma exigua var.foveata (Phoma-F?ule) ermittelt. Die Knollen wurden nach oft unterschiedlicher Behandlung angepflanzt und das Vorkommen der Pathogene an den Tochterknollen nach Ernte und weiterer Lagerung festgestellt. Die Versuche wurden mit Pflanzknollen durchgeführt, die in der ‘DAFS nuclear stock farm” erzeugt wurden. Die Pathogene wurden lediglich an den Knollen des Anbaus von 1977 nachgewiesen, und dies auch nur in sehr geringem Masse (Tabelle 1). Der Befall der Pflanzknollen war w?hrend der Lagersaison 1976/77 im Lager C am h?chsten und im Lager A am niedrigsten (Tabelle 2). In gleicher Weise variierte mit der Lagerung der Befall der Tochterknollen, wenn auch für die Sorte Kerr's Pink der Unterschied zwischen den L?gern B und C nicht signifikant war. Der Umfang desP. pustulans-Befalls war an den Tochterknollen signifikant (r=0,84; 22 d.f) bezogen zum Vorkommen der Tüpfelflecken. Zwei weitere Experimente best?tigten, dass der Knollenbefall mitP. pustulans mit dem Lager variierte (Tabelle 3). Die Kontamination der Tochterknollen wurde nicht durch die Begasung der Pflanzknollen mit 2-Aminobutan bei der Ernte beeinflusst. In zwei Versuchen wurde der Befall der Tochterknollen mitP. pustulans reduziert, in dem die Pflanzknollen aus Lager C entweder in Oberfl?chen-Desinfektionsmittel oder in ein Fungizid (Thiabendazol) getaucht wurden (Tabelle 4). Dieses Ergebnis best?tigte sich in zwei weiteren Versuchen, in denen Pflanzknollen der L?ger A, C und L verwendet wurden (Tabelle 5). Der Befallsumfang der Pflanz- und Tochterknollen mitP. exigua var.foveata wurde vom Lager, in dem sich die Knollen befanden, nicht beeinflusst (Tabellen 2 und 3). Die Kontamination der Tochterknollen wurde auch nicht durch die chemische Behandlung kurz vor dem Pflanzen berührt (Tabellen 4 und 5). Im Gegensatz zu diesen Versuchen, bewirkte das Best?uben der Pflanzknollen mit trockener, kontaminierter Lagererde einen h?heren Befallsgrad der Tochterknollen als das Best?uben mitP. exigua var.foveata freier Erde (Tabelle 6). Diese Ergebnisse wurden in Bezug zu einem luftbürtigen Inokulum diskutiert, das man von einem in Kartoffell?gern vorkommenden kontaminierten trockenen Boden erhielt (Carnegie et al., 1978).
Résumé Entre 1976 et 1981, des plants sains ont été conservés dans 5 locaux utilisés pour la conservation des stocks issus de boutures indemnes de virus. La fréquence dePolyscytalum pustulans (Oosporiose) et dePhoma exigua var.foveata (Gangrène) a été notée après 4 mois de conservation. Les tubercules ont été plantés, souvent après divers traitements, et l'incidence des parasites sur leur descendance évaluée après récolte puis après conservation. Les expériences ont été conduites en utilisant des plants en provenance de la station DAFS produisant le matériel de base. Les parasites n'ont été détectés que sur des tubercules de la récolte 1977, et à un niveau très bas (tableau 1). La contamination des plants parP. pustulans, pendant la période de conservation 1976–77 est la plus importante pour le magasin C et la plus faible pour le magasin A (tableau 2). La contamination des tubercules fils varie de la même fa?on, en fonction du local de stockage, bien que la différence entre les locaux B et C ne soit pas significative pour la variété Kerr's Pink. Sur les tubercules fils, la fréquence de la contamination parP. pustulans et la fréquence de l'Oosporiose sont significativement corrélés (r=0,84; 22 d.f.). Deux autres expériences confirment que la contamination des tubercules varie avec le local de stockage (tableau 3). La contamination des tubercules fils n'est pas modifiée par la fumigation des plants à la récolte par le 2 aminobutane. Dans deux essais, la fréquence de la contamination des tubercules fils parP. pustulans est réduite par le trempage des tubercules de semences venant du local C soit dans des désinfectants superficiels soit dans un fongicide, le thiabendazole (tableau 4). Ce résultat est confirmé par deux autres essais ultérieurs utilisant des plants provenant des locaux A, C et L (tableau 5). La fréquence de la contamination des plants et des tubercules fils parP. exigua var.foveata n'est pas modifiée par la nature du local dans lequel les plants ont été conservés (tableaux 2 et 3). Parallèlement, la contamination des tubercules fils n'est pas modifiée par un traitement chimique appliqué juste avant plantation (tableaux 4 et 5). Par opposition à ces données expérimentales, le saupoudrage des plants avec de la terre sèche contaminée prélevée dans un local, conduit à une augmentation de la contamination de la descendance, comparée à un saupoudrage effectué avec de la terre indemne deP. exigua var.foveata (tableau 6). Ces résultats sont discutés en se référant à l'inoculum aérien provenant de la terre sèche contaminée présent dans les locaux de stockage (Carnegie et al., 1978).相似文献
10.