Can Red LED Lighting Control Powdery Mildew

Get Out The Red LED Christmas Lights

Recent research by S. Suthaparan et al at the Dept of Plant Pathology at Cornell U, Geneva, NY has shown a rather interesting phenomenon

It turns out that by exposing plants to red light from LED for as little as one hour at night can whack powdery mildew

In some way, the red light from an LED inhibits sporulation (the spores being formed) on the mildew so it can’t spread. Blue light increases sporulation just for the record.

What doesn’t appear clear yet is whether the effect is from the plant doing something in a defensive way because of the light or the mildew not being able to do something because of the light. All they know is powdery mildew doesn’t spread or live under red LED lighting

The report also indicates red light can have other effects (we already know that different colored mulches increase/decrease yields on tomatoes – go with red mulch for tomatoes) on plants

From a practical point of view, this doesn’t have too much impact in the garden unless you wanted to floodlight your Phlox paniculata and roses with red LED lighting at night. But indoors where powdery mildew is a problem on some plants (can you say citrus) then yes, it has immediate impact. Find some red LED light strings this Christmas and light ’em up over your houseplants for at least an hour a night this winter and see what happens

At the very worst, you have an extra string of red lights next Christmas. At best, you don’t have powdery mildew on your indoor plants

Reference: A. Suthaparan, S. Torre, A. Stensvand, M.L. Her- rero, R.I. Pettersen, D.M. Gadoury (Dept. of Plant Pathology and Plant-Microbe Biology, Cornell University, New York State Agri- cultural Experiment Station, Geneva, NY 14456), and H.R. Gislerød, “Specific Light-Emitting Diodes Can Suppress Sporu- lation of Podosphaera pannosa on Greenhouse Roses,” Plant Disease 94(9), September 2010, 1105-1110. (American Patho- logical Society, 3340 Pilot Knob Rd., St. Paul, MN 55121-2097.)

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