A step forward in all-natural pesticides

Scientists may have developed a method for using a plant's natural repellent to ward off pests.

Plants attacked by pests produce a repellent chemical called jasmonic acid. Scientists have long known that spraying this natural pesticide on crops helps protect them from bugs. Using it agriculturally might preclude the need for environmentally damaging human-made pesticides or genetically modifying plants to resist pests. So why haven’t farmers adopted it? It turns out that treated plants grow more slowly.

Now, scientists at Lancaster University’s Environment Centre and Stockbridge Technology Centre in Britain may have devised a way to use jasmonic acid’s repellent power without slowing plant growth. The secret? Dip seeds in it. Exposure to jasmonic acid primes resistance to pest attack later when seeds become plants. The protective effect lasts at least 10 weeks after germination. In the lab, it cut mite attacks on tomatoes by 80 percent, aphid attacks on peppers by 70 percent, and caterpillar damage to corn by 38 percent.