Increased Chlorophyll Efficiency of Dark-adapted Camellia Foliage when Treated with Chlorine Dioxide or Hydrogen Peroxide and Blended with an Ionic Surfactant

Tuesday, July 23, 2013
Desert Ballroom: Salons 7-8 (Desert Springs J.W Marriott Resort )
Debra Newman , United States Department of Agriculture Animal & Plant Health Inspection Service, Fort Collins, CO
Heather Hammack , Colorado State University, Fort Collins, CO
Craig Ramsey, Ph.D. , USDA, APHIS, Fort Collins, CO
Steven Earl Newman, Ph.D., A.A.F. , Colorado State University, Fort Collins, CO
Phytophthora ramorum is a major risk to interstate trade of nursery stock. Our work focuses on chemical oxidant chemistry as a disinfectant on nursery grown Rhododendron species. Disinfection of the plant is crucial, but the impact on plant health and phytotoxic responses are also important. To determine plant stress responses to applied chemical oxidants, we are measuring chlorophyll activity (PSII quantum efficiency) as measured by Fv/Fm values in dark-adapted camellia plants. Data were collected using a Li-Cor 6400 Leaf Chamber Fluorometer (Li-Cor, Lincoln, NE) to evaluate the potential phytotoxicity of Camellia to ClO2 and H2O2 at various concentrations, with or without the surfactant sarcosinate, and consecutive sprays. Chlorophyll activity (Fv/Fm) of dark adapted camellia foliage was greater when ClO2 and H2O2 were applied with the surfactant sarcosinate to camellia foliage. Chlorophyll activity decreased with increasing concentrations of ClO2 increased when sarcosinate was not present. No differences between ClO2 and H2O2 solutions at the similar concentrations were observed. Visual injury of the camellia foliage increased with each subsequent spray application; however, foliar injury did not exceed a marketable threshold for most treatments, until after four or five consecutive spray applications at 400 mg·L-1 ClO2, with or without surfactant.
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