Farmer Rafik Danwade had been pumping more pesticides on his acre-long field in Jambhali village in India’s Maharashtra state, but the chemicals were getting less effective at protecting his 3,200 chili plants from nematodes and other bugs. So Danwade, 56, turned to a practice his grandfather taught him in the 1970s: He planted 1,000 marigolds on the border and alternating rows of the field.
“Sometimes you must look into the past to find solutions for the present and future problems,” Danwade said.
He and other farmers around the world are relearning the ancient wisdom of sowing plants known as trap crops to protect their harvests from pests. The lessons must be relearned now because climate change has raised temperatures and humidity, leading to increased pest attacks in many regions of the globe.
Marigolds produce compounds that suppress the root-knot nematodes, killing the pests that enter their root systems or contact soil containing a marigold’s bioactive compounds. The bright yellow and orange flowers also release compounds that deter aphids and whiteflies. For Danwade, marigolds also act as a natural barrier, confusing pests looking for his chili plants. Experiments conducted between 1990 and 1993 in India found that African marigolds also effectively managed the cotton bollworm pest on tomatoes.
The eco-friendly method vastly reduces the need for pesticide use at a time when several parts of India and the world have reported increased pest attacks. This method is much healthier for farmers working the fields, people consuming the crops, and soil quality.
Global warming could expand the geographic range of pests, increase the number of generations, and make it easier for invasive insect species to survive the winter season. Pests already destroy 20% to 40% of crop production worldwide every year. According to the U.N.’s Food and Agriculture Organization, insect attacks cause a loss of $70 billion annually, while plant diseases cause a staggering loss of $220 billion. Trap crops could lower these losses while reducing the need to use excess chemical pesticides, which in addition to harming health, also contribute to climate change.
