Blog Entry Holly and Caitlin - September 21-23, 2012

Controlling pests and diseases is a constant concern in greenhouses and much of this weekend was spent focusing on these issues. Sanitation and biological controls were applied in order to address these issues.

The greenhouse was thoroughly cleaned: benches, table tops, and other surfaces were scrubbed in order to minimize the risk of contaminants.  Floors were washed down, debris and organic matter was removed from drains and pots were sterilized which should reduce the chances of disease spreading to plants from these sources.

The poinsettias (Euphorbia pulcherima) are the main crop in the greenhouse and thus a significant part of the weekend was spent ensuring that they are happy and healthy.  All necrotic tissue was removed and individual plants suffering from root rot were removed and composted to prevent disease from spreading in the crop. The poinsettias were also carefully watered, taking care not to overwater as poinsettias are prone to root rot which is caused by excess water. So plants are kept on the dry side.

The poinsettias also had biological controls applied to them in order to minimize infestations of thrip and white fly infestation.  Parasitic wasps Encarsia formosa (good for greenhouse white fly not silverleaf whitefly) which were on biotags. Amblyseius swirskii for thrips introduce when levels are low and use high enough intro rate to achieve success.

The top priority this weekend was getting the greenhouse set up for the poinsettia () crop photoinduction cycle. Poinsettias’ have photoperiodic flowering which means that flowering is physiologically induced by day or night length. Poinsettias are short day plants, which means that if day length exceeds 11.5 hours flowering will not occur. Since we want the poinsettias to be ready for sale in Nov.-Dec. It is necessary to artificially lengthen the night to approximately 15 hours to ensure that flowering and bract colour occur.

Artificially lengthening the night period was accomplished by installing blackout curtains along the greenhouse walls which are manually closed at 5:00pm and opened at 8:00am (15 hour dark period).  The energy curtain was reprogrammed using PRIVA so that it will also close at 5:00pm and open at 8:00am which prevents light from entering through the ceiling during the required dark period.