Powdery Mildew Fungus (IMAGE) University of Helsinki Caption To the naked eye, the infection appears as white fungal spore growth covering the plant. A powdery mildew fungus is a common parasite of the ribwort plantain. Credit Elina Numminen Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.