Hello Gardeners, I’m Amanda McNulty with Clemson Extension and Making It Grow . A cultivar is a named variety of a particular plant that was selected or breed and vegetatively propagated to have special characteristics, so all the plants with that name are exactly the same. It used to be that people often planted seedling dogwoods in their yards. But today there are many diseases of dogwoods – two types of anthracnose, powdery mildew and other leaf spot infections – some more serious than others