Notes on Wisconsin parasitic fungi. XXVI.

Abstract

The fungi referred to in this series of notes were, unless it is stated otherwise, collected during the season of 1946. Powdery mildews which fail to produce perithecia, each season attack various host plants. 'Specific identification is uncertain, but there is no question as to parasitism. On some of the hosts the organisms occur regularly in the non-fruiting stage from year to year. It seems worth while to record these where there is no previous Wisconsin record of any powdery mildew on the host concerned. Examples observed in 1946 are Pilea pumila, Dane Co., Madison, September 27; Erucastrum gallicum, Madison, September 17; Desmodium nudiflorum, Sauk Co., Devils Lake, June 26; Rhus copallina, Columbia Co., Lodi, August 6; Monarda punctata, Dane Co., Pine Bluff, August 29; Solidago sciaphila, Sauk Co., Cactus Bluff, Town of Prairie du Sac, August 23; Solidago speciosa, Madison, September 15; Solidago ulmifolia, Sauk Co., Devils Lake, August 5; Solidago patula, Waukesha Co., Hartland, September 15; Euthamia graminifolia, Madison, September 15; Aster ericoides, Madison, July 5; Helianthus rigidus, Dane Co., Westport, September 10; Rudbeckia laciniata, Sauk Co., Parfrey's Glen, July 6 (widespread infection every year on this host); Cacalia tuberosa, Madison, July 22; Lactuca ludoviciana, Madison, August 27.