We were pointed to a post on the use of light to control powdery mildew in greenhouses.  This is yet another example of growing awareness of the fantastic complexity of life and the many and varied roles that light and light quality play on growth of crop, pests and diseases.

The collaborative project by Cornell researchers and colleagues in Norway studied the effect of light on powdery mildew – a group of tiny, transparent parasitic fungi that infect many crops, including cucumber, grapes and berries.

Work by Aruppillai Suthaparan of the Norwegian University of Life Sciences and Cornell plant pathologists Robert Seem and David Gadoury, published in the May issue of the journal Plant Disease, found that UV-B light suppressed cucumber powdery mildew and was especially effective when applied at night. They could use light to suppress the pathogen without the use of costly fungicides.

The researchers infected cucumber plants with powdery mildew and applied UV-B for short spurts of five, 10 and 15 minutes. They found that UV-B exposure reduced cucumber powdery mildew infection from about 90 percent of leaf area to about 5 percent, and also reduced the formation of spores.

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