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Title: The influence of phosphorus concentration on the development of Pythium root rot disease of seedling geranium

Author
item Omer, Medani
item Locke, James
item Frantz, Jonathan
item Krause, Charles

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 4/30/2008
Publication Date: 6/16/2008
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.

Interpretive Summary:

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.