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Weeds act as alternative host of many plant pathogens as they serve source of over-wintering for a wide range of pathogens and effects on all aboveground parts of the plant. Perennials weeds play important role in the spreading of obligate pathogens. Among the prevalent diseases caused by obligate fungal pathogens, powdery mildew is counted in most common diseases especially for vegetables and ornamental plants in Pakistan. The pathogens Erysiphe cichoracearum, Sphaerotheca fuliginia, and Leveillulata urica have been reported on Convolvulus arvensis, Argemone mexicana, Rumex obtusifolious and Rumex dantatus, Euphorbia hirta, Conyza ambigua, Cucumis melo var. Agrestis and Chenopodium murale in Lahore, Faisalabad, Gujranwala and Sheikhupura districts of Central Punjab. Distribution assessment on a visual 0–5 visual rating scale was recorded at 4 severity rating on C. arvensis, while other weeds showed intermediate reaction except C. melo proved highly resistant against powdery mildew.