Scientists discovered a tiny regulatory RNA molecule called LtmilR2 in a fungus that causes grape disease. This molecule naturally suppresses the fungus’s ability to cause infection by shutting down a gene called LtRASGEF. When researchers delivered LtmilR2 using specially designed nanoparticles, it successfully stopped the fungus from growing. This discovery could lead to a new type of biological fungicide for protecting grapes and vineyards.