Greenhouse Canada

WEBINAR: Cultural controls for managing and preventing disease

February 21, 2019  By Greta Chiu

Speaker: Dr. John D. Lea-Cox, University of Maryland

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Can’t seem to figure out where disease is coming from? From clean stock and substrates, to irrigation water recycling and sanitation, learn about the cultural control methods that could help prevent and manage diseases in your greenhouse operation.

Questions for Lea-Cox answered after the webinar:

1. What do you think about chlorination of water? Do plants react to combined chlorine (chloramines), which are formed in reactions between Cl and organic matter and then build up over and over? Is there any risk of phytotoxicity same as in the case of free Cl, which is well-known?

Lea-Cox says: I would refer this person to talk directly with Dr. Paul Fisher at the University of Florida or Dr. Rosa Raudales the University of Connecticut who are expert on this matter. There is also some general information on the SCRI-WateR3 website for chlorination under the pathogens and biofilms tab.

2. You talked about the 3 aspects of a good media (good drainage, water holding, nutrient holding). How can a grower test new media to determine if it meets production needs and is of good quality?

Lea-Cox says: My colleague, Dr. Andrew Ristvey (the substrates expert at UM I mentioned) has a quick easy procedure that growers can do to ascertain their AFP and WHC, without any fancy equipment.

For nutrient testing, we use a “tip-test” or quick SME procedure to measure electrical conductivity. I think Dr. Ristvey also has a protocol for that, although that information is readily available from various sources.


Lea Cox
About the speaker:
John D. Lea-Cox, PhD, is a professor and research and extension specialist for the nursery and greenhouse industry at the University of Maryland. With primary expertise in the areas of water and nutrient management, his work aims to systematically reduce the environmental impacts of industry production practices. His major research interests are in the areas of wireless sensor networks, soilless substrates, disease management, frost and environmental monitoring and more.

Chevonne webinarAbout the moderator: Chevonne Carlow, PhD, is the greenhouse floriculture specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA). Chevonne works to connect growers with up-to-date information on floriculture crop production, nutrition and related issues. In addition, she is involved in a wide variety of collaborative research and demonstration projects related to the floriculture sector.


Don’t forget to register for other webinars in this Let’s Talk Disease series for ornamentals: