Reminders
for Cleanup
| Author: |
Gillian Ferguson
- Greenhouse Vegetable IPM Specialist/OMAFRA
|
| Creation Date: |
Not Available
|
| Last Reviewed: |
Not Available
|
To minimize carryover of disease-causing organisms to the new crop,
and to facilitate management of pests and diseases in the subsequent
crop, a good cleanup is essential. Although the procedure for cleanup
has become routine in most operations, there are some key points that
growers need to remember as they go through the cleanup process.
- Clean surfaces before Disinfecting - Removing all inorganic (e.g.
calcium deposits) and organic residues (e.g. plant debris) is critical
to achieving a good cleanup. Inorganic deposits can harbour disease-causing
micro-organisms, and organic residues greatly reduce the effectiveness
of all disinfectants by interacting with them and providing protection
for pathogens. An effective method of cleaning surfaces is use of
soap and water applied at high pressure before the disinfection
process. Soap is especially useful in removing greasy deposits.
A thorough rinsing after washing with soap is best because soap
residues can inactivate certain types of disinfectants such as quaternary
ammonium compounds.
- Pay attention to all surfaces - In particular, horizontal surfaces
at higher levels in the greenhouse can be overlooked. Many disease-causing
organisms are lodged on rafters, window ledges, tops of overhead
piping etc. Power-washing from below will not adequately clean such
areas. Additionally, extra care is needed in cleaning the textured
surfaces of cement, wood, etc. which can hide many kinds of organisms.
- Note pH effects - Soaps are alkaline and residues can either
inactivate certain disinfectants, as mentioned above, or reduce
the effectives of those disinfectants that work optimally at an
acidic pH. Bearing the influence of pH in mind, it is best to use
one type of disinfectant if multiple applications of disinfectants
are being made. As long as proper concentrations are used and sufficient
contact times are allowed, the disinfectant of choice should be
effective. Note also that disinfectants are best applied to dry
surfaces because wet surfaces dilute the concentration of the disinfectant
applied.
- Allow sufficient contact time with Disinfectants - Note that
no disinfectant works instantaneously. A certain amount of contact
time is required for maximum effectiveness, and the time required
for contact is influenced by temperature and concentration of the
disinfectant. Generally, higher temperatures increase efficiency
of disinfectants by two- to three-fold for every 100C rise in temperature
whereas lower temperatures do the opposite. For example, the effectiveness
of chlorine is reduced by 50% at 100C.
- Note hardness of water used for Disinfection - Some disinfectants,
particularly quaternary ammonium compounds, are deactivated by hard
water, i.e. water with high levels of calcium and magnesium. It
is advisable to test water for hardness and for contamination before
use.
- Be mindful of Re-contamination - Growers need to maintain sanitation
protocols to minimize re-contamination of the "cleansed"
greenhouse. So, provision of disinfection boot trays or clean foot
wear dedicated to use in the greenhouse, proper cleaning and disinfection
of all equipment used in the greenhouse, etc. are in order.
These reminders provide the basis of a good cleanup job. Throughout
this process, growers are also reminded to carefully read labels of
all products used and to follow safety precautions recommended.
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