Phytoparasitica (2002) 30, 67-76

Yannis Raftoyannis and Michael W. Dick (2002)
Effects of inoculum density, plant age and temperature on disease severity caused by pythiaceous fungi on several plants
Phytoparasitica 30 (1), 67-76
Abstract: Alfalfa, maize, sorghum and sugarbeet plants were inoculated with zoospores of Phytophthora and Pythium species in order to assess the effects of inoculum density, plant age and temperature on disease severity. Seedlings were grown axenically in test tubes and inoculated with zoospore suspensions. Disease severity was assessed by measuring the root growth and discoloration of treated and control seedlings. The incremental root length of all plants decreased and root discoloration increased as inoculum concentration of the pathogen increased. Changes were more intensive among low levels of zoospore concentrations and no significant differences in disease severity were found for inoculum densities higher than 10⁴ zoospores ml^-1. Disease severity was negatively related to plant age. Disease development on sugarbeet seedlings infected with Pythium and Phytophthora species was affected by temperature, but the pattern of response was determined by the pathogen's temperature preferences. The incremental root length decreased as temperature increased up to 25°C. The effect of Pythium dissimile and Phytophthora cactorum on root length was significantly lower at 35°C than at 25°C, whereas Pythium aphanidermatum and Phytophthora nicotianae caused significant damage to roots even at 35°C.
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Link to article at publishers website
Database assignments for author(s): Yannis Raftoyannis

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

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Phytophthora cactorum
	Pythium aphanidermatum
	Pythium dissimile
	Phytophthora nicotianae