C. trifolii

C. trifolii may refer to:
 * Coleophora trifolii, the trefoil thick-horned tinea or large clover case-bearer, a moth species found in Europe, North Africa, Asia Minor, Afghanistan and North America
 * Colletotrichum trifolii, a fungal plant pathogen of alfalfa
 * Curvularia trifolii, a plant pathogen
 * Cymadothea trifolii, a fungal plant pathogen