Photoprotection by plant extracts: a new ecological means to reduce pesticide photodegradation.

A pesticide's reactivity toward light at the leaf surface after crop treatment is rarely considered, although such degradation reactions directly affect the pesticide's effectiveness. To overcome these limitations, the use of plant pigments was proposed as a new class of photoprotecting agent. The photoprotecting properties of seven plant pigments were tested under controlled conditions over herbicide sulcotrione. Grape wine extracts were tested over a panel of pesticides from distinct chemical families. The addition of plant extracts almost systematically reduced the pesticide's photoreactivity. The grape wine extracts improve at least by 38% the half-life of photolysis of almost all of the active ingredients tested, except for the herbicide triclopyr. Fustictree extract increases by 82% the photostability of the herbicide sulcotrione. Plant extracts mainly act as sunscreens; that is, the photostabilization of the active ingredient is due to the competitive energy absorption of UV photon. The use of natural plant extracts is a promising strategy to limit pesticide photodegradation. It is a way to develop sustainable and innovative technology for the plant protection industry, being beneficial from both economic and ecological points of view.