Abstract
The occurrence of Erysiphales in selected regions of Northern Poland was studied in detail between 1981 to 1991. Special attention was paid to the degree of infection of host plants caused by powdery mildew. More species of fungi were found in urban regions, but in several cases the severity of lesions was greater in suburban areas. A hypothesis is put forth that urban environmental pollution inhibits the development of the studied fungi.
Keywords
host plants; immunity; urban pollution; physiological changes; powdery mildew; lesions