Outdoor & Protected Cultivation

Rain, Dew & Flower Disease Risk

Flower disease risk rises when susceptible tissue stays wet or humid for extended periods, especially inside dense floral clusters with limited air exchange.

Key concepts

  • Dew can wet flowers even without rainfall
  • Dense canopies create local humidity different from weather-station readings
  • Cool nights can increase condensation risk
  • Dead or damaged tissue can provide infection sites

What to measure or observe

  • Inspect flowers after rain and heavy dew
  • Record overnight RH and temperature when possible
  • Check dense interior flower zones
  • Track periods of persistent cloud, fog, or repeated wetting

Common mistakes

  • Using daytime humidity as the only risk indicator
  • Assuming outdoor wind reaches the interior of every flower
  • Waiting for obvious gray sporulation before inspecting

Visuals this lesson still needs

  • Dew formation diagram
  • Flower microclimate cutaway
  • Wetness-duration timeline
  • Disease-risk inspection map