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United States Department of Agriculture

Agricultural Research Service

Research Project: Alternatives to methyl bromide soil fumigation for vegetable and floriculture production

Location: Subtropical Plant Pathology Research

Title: Dose response of soilborne plant pathogens and Meloidogyne incognita to citrus-based experimental compounds.

Authors
item Iriarte, Fanny
item Rosskopf, Erin
item Burelle, Nancy

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: October 11, 2011
Publication Date: July 26, 2008
Citation: Iriarte, F.B., Rosskopf, E.N., Burelle, N.K. 2008. Dose response of soilborne plant pathogens and Meloidogyne incognita to citrus-based experimental compounds. Phytopathology. 98:S71

Technical Abstract: Two novel citrus-based compounds have been tested in vitro against Colletotrichum gleosporioides, Fusarium oxysporum, Sclerotinia sclerotiorum, Sclerotium rolfsii, Rhizoctonia solani, Verticillium albo-atrum, Pythium aphanidermatum, P. myriotilum, Phytophthora nicotianae and P. capsici. One of the compounds, referred to as Citroxin (aka Oraphyte), contains hydrogen peroxide and the other compound, Citroxin O2 (aka Oraphyte O2) does not. Both compounds were effective in controlling all fungi tested at concentrations ranging from 1 to 4 %. The formulation containing hydrogen peroxide was more effective for controlling C. gleosporioides, V. albo-atrum, F. oxysporum,P. nicotianae, and P. myriotilum, while Citroxin O2 was more effective for S. sclerotiorum and S. rolfsii. No significant difference in percent kill was found for R. solani, P. aphanidermatum or P. capsici up to 2%, after which higher concentrations of Citroxin were more effective than Citroxin O2. IC50’s ranged from 0.6 to 1.3% for Citroxin, and 0.6 to 2 % for Citroxin O2. Meloidogyne incognita juvenile nematodes were killed in vitro with a concentration of 1% of both formulations. In addition, egg hatch was inhibited at 1 % with Citroxin and 2% with Citroxin 02. In greenhouse experiments, a post-transplant drench of 25 % Citroxin provided control of Phytophthora blight of pepper. In tomato, the same concentration significantly reduced the number of root-knot nematode galls and number of eggs per gram of root without causing phytotoxicity.

Last Modified: 8/27/2014
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