Researchers discovered that betulinic acid, a natural compound found in birch and eucalyptus trees, can slow down turnip mosaic virus infection in plants. The compound works by activating a plant hormone called phytosulfokine through special receptors on plant cells, which strengthens the plant’s natural defence against the virus. This finding suggests betulinic acid could become an environmentally friendly alternative to chemical pesticides for protecting vegetable crops from viral diseases.