PHYSIOLOGICAL RACES OF THE CUCURBIT POWDERY MILDEW AGENT IN APULIA

The development of cultivars displaying durable resistance to powdery mildew is one of the major aims of cucurbit breeding programmes. For a reliable assessment of the resistance of different plant genotypes, a comprehensive knowledge on the virulence of the pathogen is required. Several physiologic...

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Bibliographic Details
Published in:Journal of plant pathology 2009-12, Vol.91 (4), p.S4.74-S4.74
Main Authors: Miazzi, M, Laguardia, C, Faretra, F
Format: Article
Language:English
Subjects:
Cucumis melo
Podosphaera xanthii
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Summary:The development of cultivars displaying durable resistance to powdery mildew is one of the major aims of cucurbit breeding programmes. For a reliable assessment of the resistance of different plant genotypes, a comprehensive knowledge on the virulence of the pathogen is required. Several physiological races of Podosphaera xanthii, the obligate biotrophic fungus agent of powdery mildew of cucurbits are known. For monitoring their distribution in Apulia (Southern Italy), 84 monoconidial isolates coming from 38 fields from different locations were obtained and maintained over a period of 3 years on cotyledons of the highly susceptible zucchini cv. Diamant 1. Physiological races were sorted out with an assay based on a set of differential hosts made up of 8 melon genotypes. Results showed that, in addition to race 2 (17% isolates), already reported in the area, races 0 (1% isolates), 1 (20%), 3 (15%), 4 (4%), and 5 (25%) were also found. About 18% of the isolates did not belong to any race, which suggests the existence of still unknown physiological races of the fungus. Differences in the distribution of races were found depending on the location of fields. The detection frequency of different races varied also with host species: race 1 was prevalent (46% of isolates) on zucchini and race 5 (44%) on Cucumis melo. Race 3 was found only on C. melo, with some differences among plant genotypes, i.e. 16% on "winter melon", 24% on "carosello" and 9% on "barattiere".
ISSN:1125-4653