Abstract
Factors for the occurrence of downy mildew on broccoli heads were observed in the field experiment. Inoculation of the fungus to broccoli plant at the stage of flower-bud emergence gave rise to head damages at harvest time. The inoculation was more promising in the mid-September than in the early September. Meteorological conditions favorable for mildew infection at the head emergence stage may result in the severest damages on broccoli heads.
