Powdery mildew
and makes it harder for the fungi to enter the leaves To reduce chances of powdery mildew in greenhouses, it is advised to first ventilate by only opening [...] colonies mostly occur in these crops. In covered roses, the colonies appear first and foremost on the upper side of the leaves. In most crops, the white [...] fairly similar in all plant-pathogen combinations. The symptoms are white fluffy colonies, first and foremost on the upper side of the leaf. In severe epidemics