Scientists have discovered that two types of fungi called Arachnopeziza species are the closest living relatives to powdery mildew fungi, which cause plant diseases. Unlike powdery mildews, these Arachnopeziza fungi can be easily grown in the lab and genetically modified. By studying these more manageable fungi, researchers can better understand how powdery mildew fungi became obligate parasites that must live on plants, potentially leading to better ways to control this widespread plant disease.