HortScience (2008) 43, 1509-1513

Mary Ruth McDonald and Sean M. Westerveld (2008)
Temperature prior to harvest influences the incidence and severity of clubroot on two Asian Brassica vegetables
HortScience 43 (5), 1509-1513
Abstract: Shanghai pak choy [Brassica rapa L. subsp. chinensis (Rupr.) var. communis Tsen and Lee] and Chinese flowering cabbage [Yow choy; B. rapa L. subsp. chinensis (Rupr.) var. utilis Tsen and Lee] were seeded into organic (muck) soil naturally infested with the clubroot pathogen (Plasmodiophora brassicae Woronin) at the University of Guelph Muck Crops Research Station, Ontario, Canada, in June, July, and Aug. 2001 and May, June, July, and Aug. 2002. At harvest, clubroot incidence and disease severity index (DSI) were assessed. Data from 17 different seedings at the research station over 4 years were used to compare the relationship between disease incidence and DSI and weather conditions during crop development. Clubroot incidence and severity were highest for crops harvested in July and August and lowest for crops harvested in October. Mean air temperatures during crop development ranged from 15 to 22 °C and were positively correlated with clubroot incidence and severity for both pak choy (r = 0.68) and flowering cabbage (r = 0.73). The strongest correlations occurred between air temperatures and disease severity over the final 10 d before harvest (r = 0.82 for pak choy; r = 0.84 for flowering cabbage). The research suggests that clubroot damage in Asian Brassica vegetables could be minimized by seeding in early spring and late summer in areas infested with P. brassicae.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Database assignments for author(s): Mary Ruth McDonald

Research topic(s) for pests/diseases/weeds:
population dynamics/ epidemiology
environment - cropping system/rotation

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Plasmodiophora brassicae	Brassica - other species	Canada (east)