Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: April 30, 2008
Publication Date: June 16, 2008
Citation: Omer, M.A., Locke, J.C., Frantz, J., Krause, C.R. 2008. The influence of phosphorus concentration on the development of Pythium root rot disease of seedling geranium. Phytopathology. 98(6):S116. Technical Abstract: In greenhouse production systems, growers may increase nutrient supply to meet production demands or decrease nutrient supply due to cost or environmental concerns. Only a few floriculture crops’ response in different nutrient environments to a handful of diseases are well known. Seeding geraniums were planted in soilless media and fertilized with Hoagland’s solution that contained a range of phosphorus concentrations, from 0.05 mM to 15 mM, and challenged with Pythium ultimum in an attempt to study the role of P in mediating disease stress. Disease severity was lowest in a P supply of 0.2 to 2.0 mM. An increase in P concentration from the concentration of 0.5 mM to 7.5 and 15 mM doubled disease severity. Lowering the P concentration to 0.05 mM resulted in a similar disease response as the highest P supply (p = 0.05). Plant biomass showed a similar trend with the highest and lowest P concentrations having similar shoot weight (p= 0.05). Data presented here showed that the use of Hoagland’s solution containing 0.2 or 0.5 mM P would help in lessening the effect of P. ultimum on seedling geranium and in increasing plant vigor. This represents a decrease of P of nearly 60% from typical production fertility programs.