Scientists tested a plant-based extract from Cinchona bark as a natural fungicide against a serious fungus that damages rice crops. The active ingredient, quinine, works by two methods: it blocks the fungus from getting the amino acid tryptophan it needs to survive, and it damages the fungus’s energy-producing structures. When researchers added tryptophan back to the treated fungus, it recovered, confirming this is how the treatment works. This natural fungicide could offer farmers an eco-friendly alternative to chemical pesticides.