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On Phaeosphaeria nodorum in wheat

Blixt, Eva (2009). On Phaeosphaeria nodorum in wheat. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2009:1
ISBN 978-91-86195-48-9
[Doctoral thesis]

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The fungus Phaeosphaeria nodorum (anamorph Stagonospora nodorum) causes stagonospora nodorum blotch on wheat. Besides environmental conditions the biology of the pathogen is an important parameter that determines the epidemiology of the disease. The dispersal pattern of the pathogen depends on the mode of reproduction. The studies reported in this thesis show that P. nodorum not only reproduces sexually but also sexually. This conclusion is based on the random distribution of the two mating types and the diverse genetic structure of the population. The sexual ascospores are windborne and able to initiate epidemics in new wheat fields, whereas asexual spores, conidia, give rise to new lesions when spread upwards in the canopy and to adjacent plants through splash water droplets. Isolates of P. nodorum vary in aggressiveness towards wheat in terms of latency period and production of pycnidia. The wheat cultivars commonly grown in Sweden have similar susceptibility to P. nodorum. Use of low inoculum concentrations could be useful in cultivar screening in breeding programs due to the comparability to natural infection. In agricultural practice, fungicides are used as a control of leaf spot pathogens. This thesis includes the first report of isolates of P. nodorum that have lost their sensitivity to the strobilurin substance azoxystrobin. The majority (79% of 227 isolates) of the P. nodorum isolates collected in 2003-2005 had the amino acid substitution g143a in the gene encoding cytochrome b, which is associated with loss of sensitivity to strobilurins in other pathogenic fungi. The substances propiconazole, prothioconazole and cyprodinil were efficient in reducing the fungal growth. Wheat leaves are colonised by other fungal species besides pathogenic fungi. The fungal community on wheat leaves also contains saprotrophic fungi and yeasts. P. nodorum was common in fields sampled in 2003 and 2004 but in 2005 the pathogenic fungi Pyrenophora tritici-repentis and Mycosphaerella graminicola, causing tan spot and septoria tritici blotch respectively, were more common in the sampled fields.

Authors/Creators:Blixt, Eva
Title:On Phaeosphaeria nodorum in wheat
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2009
Number of Pages:55
ALLI. Blixt E., Olson Å., Lindahl B., Djurle A., Yuen J. Spatiotemporal variation in the fungal community associated with wheat leaves showing necrotic leaf spots. (Manuscript). II. Blixt E., Olson Å., Högberg N., Djurle A., Yuen J (2008). Mating type distribution and genetic structure are consistent with sexual recombination in the Swedish population of Phaeosphaeria nodorum. Plant Pathology 57, 634-641. III. Blixt E., Djurle A., Olson Å, Yuen J. Variation in aggressiveness of Phaeosphaeria nodorum to six Swedish winter wheat cultivars. (Manuscript). IV. Blixt E., Djurle A., Yuen J., Olson Å. Fungicide sensitivity in Swedish isolates of Phaeosphaeria nodorum. (Accepted for publication in Plant Pathology).
Place of Publication:Uppsala
ISBN for printed version:978-91-86195-48-9
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:triticum aestivum, cereal crops, varieties, leptosphaeria nodorum, stagonospora, fungal diseases, genetic variation, sexual reproduction, disease transmission, leaves, fungicides, sweden
Keywords:aggressiveness, cultivar, fungal community, fungicide, genetic diversity, sexual recombination, stagonospora nodorum blotch, Phaeosphaeria nodorum, wheat
Permanent URL:
ID Code:1912
Department:(NL, NJ) > Dept. of Forest Mycology and Plant Pathology
(S) > Dept. of Forest Mycology and Plant Pathology
Deposited By: Eva Blixt
Deposited On:12 Dec 2008 00:00
Metadata Last Modified:02 Dec 2014 10:15

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