July 22, 2014 by Francesca Peduto Hand, Nancy J. Taylor, Beth Scheckelhoff and Luis Cañas.
Over the course of a growing season, plant pathogens and algae flourish on greenhouse surfaces – often harboring pests such as fungus gnats and shore flies. Plant diseases and other insects cause havoc during the production season. Proper disinfection and cleaning should be done routinely though timing does not always allow for it. Now that your greenhouses are emptying, it is the perfect time to thoroughly clean them!
Pests and diseases are much easier to prevent than to cure, so we strongly suggest cleaning debris from the previous growing season now. The goal is to eliminate pathogen inoculum and pest populations prior to the next growing cycle. Do not wait until shortly before re-opening to clean.
Here are a few steps for proper greenhouse cleaning:
- Physically remove pet plants, plant debris, soil, and weeds from benches, underneath benches and all floors. Begin at the top and work your way down.
- Next, use a cleaning product specifically labeled for greenhouse use to remove algae, dirt and other deposits from greenhouse surfaces. Don’t forget to thoroughly clean walls, internal structures, and textured surfaces as pathogens can hide in many places including the folds in plastic, porous materials, rafters, on top of overhead piping etc. Thoroughly clean benches and worktables, which, as a reminder, should be made of non-porous materials that are easily disinfected.
- Wash all containers that will be reused to remove soil particles and plant debris. Next, treat them with a labeled disinfectant regardless if there was a disease present in the crop. ***Spores of some common root pathogens such as Pythium and Thielaviopsis can survive in root debris or soil particles on pots, flats or other containers. If you have a history of these diseases affecting your crops, it is recommended not to reuse them.***
The picture above shows debris and plants that need to be removed during the summer cleanup process.
Examples of cleaning agents (the list is not all inclusive):
Quaternary ammonium compounds
1- Green-Shield® – Quaternary Amine
2- KleenGrow™ – Didecyl dimethyl ammonium chloride
3- Physan 20® – n-alkyl dimethyl benzyl ammonium chloride +
n-alkyl dimethyl ethylbenzyl ammonium chloride
4- ZeroTol® 2.0 – Hydrogen Dioxide
5- Oxidate® 2.0 – Hydrogen Dioxide, OMRI listed
Hydrogen peroxide & peroxyacetic acid
6- Sanidate® – Hydrogen Peroxide + Peroxyacetic Aci
7- Chlorine bleach
8- Alcohol, useful to disinfect propagation tools.
University of Massachusetts
Oregon State University
Note: Remember to read all labels. It is always the applicator’s responsibility, by law, to read and follow all current label directions for the specific product being used. The authors and Ohio State University assume no liability resulting from the use of these recommendations.
Francesca Peduto Hand
Assistant Professor and Extension Specialist
Department of Plant Pathology
Nancy J. Taylor
C. Wayne Ellett Plant & Pest Diagnostic Clinic
Extension Educator – Greenhouse Systems
Associate Professor and Extension Specialist
Department of Entomology