Plant Disease (2015) 99, 1823-1831

Takeshi Toda, Akinori Iwasa, Shinichi Fuji and Hiromitsu Furuya (2015)
Widespread occurrence of Pythium arrhenomanes pathogenic to rice seedlings around Japanese rice fields
Plant Disease 99 (12), 1823-1831
Abstract: In Japan, rice seedlings grown in nurseries and used for transplanting are subject to a damping-off disease caused by Pythium spp. In this study, 148 isolates of Pythium spp. were obtained from rice seedlings in 39 locations of northern Japan. Among the isolates, 137 were identified as Pythium arrhenomanes using polymerase chain reaction (PCR) with species-specific primers, DNA sequencing analyses of the internal transcribed regions of ribosomal DNA, and the morphologies of oogonia, antheridia, oospores, and zoosporangia. Inoculation tests showed that the isolates identified as P. arrhenomanes were pathogenic to rice seedlings and parasitic to southern crabgrass with only minor damage. P. arrhenomanes was reisolated from the roots of both rice seedlings and southern crabgrass. Poaceae weeds, hosts of Pythium spp., grow in and around nurseries and in ridges surrounding rice fields. To detect Pythium spp., 188 Poaceae weeds were collected from 37 locations in Akita Prefecture. P. arrhenomanes was frequently detected in 164 weed roots from all locations by PCR using species-specific primers. Thus, we determined that P. arrhenomanes exists in and around rice seedling nurseries and rice fields, and that it is much more widely distributed than previously recognized in northern Japan.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Shin-ichi Fuji, Hiromitsu Furuya

Research topic(s) for pests/diseases/weeds:
environment - cropping system/rotation
general biology - morphology - evolution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Pythium arrhenomanes	Rice (Oryza)	Japan