Scientists developed easy-to-apply spray coatings made from natural fatty acids that repel water and kill fungal infections like gray mold. By combining long-chain fatty acids with shorter fatty acids like those found in food preservatives, the coatings can either passively prevent fungus from sticking to surfaces or actively kill it. These coatings are environmentally friendly, sustainable alternatives to chemical fungicides that fungi are becoming resistant to, and could be used to protect everything from building surfaces to stored crops.