ARS | Publication request: Detecting Root Rot Stress in Geranium by Measuring Changes in Leaf Temperature

Submitted to: Survey Notes
Publication Type: Research Notes
Publication Acceptance Date: September 15, 2007
Publication Date: October 1, 2007
Citation: Omer, M.A., Locke, J.C., Frantz, J. 2007. Detecting Root Rot Stress in Geranium by Measuring Changes in Leaf Temperature. Northwest Ohio's Commercial Greenhouse Resource. 3(6):4-5.

Technical Abstract: Our objective was to determine if changes in geranium leaf temperature, measured by infrared (IR) transducers aimed at the plant canopy or individual leaves, correlate with root infection by pathogenic water molds. This is the first report to our knowledge that addresses the use of environmental sensors to detect disease stress on a geranium–water mold system. If successful, leaf temperature could be used to nondestructively indicate infection of greenhouse-grown plants, perhaps before visible symptom development. 1) Differences in leaf temperature among treatments were noticeable 2 weeks after inoculation. However, visual disease symptoms were not detected until 3 weeks after inoculation. 2) We speculate that the increase in leaf surface temperature in response to stress was incited by the exposure of geranium to pathogens. This is the first report to our knowledge that addresses the use of environmental sensors to detect disease stress on a geranium–water mold system. 3) The use of leaf surface temperature could be a reasonable nondestructive, noninvasive technique to predict plant stress resulting from infection by pathogens before symptom appearance if used in conjunction with other tests and observations to rule out other factors contributing to a rise in leaf temperature.