Growing in a greenhouse; leaves curling up, canoeing; powdery mildew starting to grow? The answer may be as simple as too much humidity in your greenhouse. The solution could be as simple as air circulation. A University of Massachusetts article explains how to reduce the humidity in your greenhouse.
The fall and spring are times when humidity related diseases usually peak in greenhouses. Sunny days increase the transpiration of moisture from leaf surfaces and evaporation from soil. The warm air holds the moisture in the vapor form. At night as the air cools to the dew point, condensation occurs and water droplets are formed on cooler surfaces such as the leaves and glazing. This moisture promotes the germination of fungal pathogen spores such as Botrytis and powdery mildew. Dripping water from condensation on the greenhouse covering also wets plant surfaces and spreads plant pathogens from plant to plant by splashing soil and plant debris. The key to successfully suppressing diseases is to keep the plant canopy dry, especially from dusk to dawn. This is accomplished through cultural practices and environmental control strategies. Read more…..