Protecting grapes from pests by boosting their natural immunity

As is true for any agricultural producer, vineyard owners need to prevent pathogens from harming their crops to stay in business. For many of them, this means applying synthetic pesticides. Out of concern for these substances’ potential effects on water, soil and human health, some winemakers have turned to more natural methods. One approach scientists are exploring involves the use of UV-C light, which studies have shown increases grapes’ production of stilbenoids. Some of these phenolic compounds have been associated with natural disease resistance. Raúl F. Guerrero from the Andalusian Institute of Agricultural and Fisheries Research and Training (IFAPA) and colleagues wanted to explore how daily doses of pre-harvest UV-C light would affect grapes’ stilbenoid content.

The researchers tested one set of grapes exposed to five minutes of UV-C light every day for three days before harvesting and compared them with another set of grapes that only received one five-minute dose. The latter technique had previously been optimized in grapes. The set that received multiple treatments showed an 86-fold increase in stilbenoid concentrations over the fruit that only got one application of UV-C. The three-day, pre-harvest treatment also affected texture, color and other characteristics, but the researchers say that the grapes were still of good quality.