Bottle gourd mosaic virus infection on the leaves of bottle gourd delayed the appearance ofSphaerotheca fuliginea (SCH.) POLL., colonies when inoculated on the same leaves. This delay varied depending upon the time interval between virus and fungus inoculation. Development of powdery mildew colonies on bottle gourd mosaic virus inoculated leaves were lesser compared to the healthy leaves inoculated only withSphaerotheca fuliginea. At the time of appearance the colony of fungus covered 2% of leaf area. After one month, it covered almost entire leaf surface, when inoculated on healthy leaves. Progress of fungal colony was checked on bottle gourd mosaic virus inoculated leaves, depending upon the time interval between inoculation of virus and fungus.