Cleaning is an important step in good store management, but will take on an additional dimension in 2020. Cleaning is usually associated with hygiene, reducing transfer of disease inoculum from one season to the next. It also has implications for chemical residues. A new, much lower, temporary Maximum Residue Level (tMRL) for CIPC is expected to be introduced next season following the chemical’s loss of approval. Cleaning your stores as soon as they are empty will therefore be critical to help avoid exceedances of this new level.
Minimising CIPC residue risk
Cleaning will be one of the key pillars of industry-wide efforts towards minimising CIPC residues and is likely to be one of the conditions imposed for any tMRL. This is part of a Europe-wide effort to maintain the tMRL at a level where industry will not be adversely affected.
Filling stores with hot CIPC fog and, in later years, using fans to recirculate it, will have ensured all surfaces in stores are covered with CIPC-contaminated dust. With some fabrics, like concrete, CIPC can even penetrate inches below the surface. Add a bit of condensation, dust and soil and deposits can become a firmly attached layer (Figure 1). Taking the following steps will help to effectively remove CIPC-contaminated dust and deposits.
A Europe-wide protocol has been released to help store managers with this task:
- All stores with a history of CIPC use must be cleaned as soon as the 2019 crop has been unloaded.
- Cleaning activities must integrate safety parameters: always use personal protection equipment (PPE) and pay attention to safety when working at height.
- Keep written records and pictures of what has been cleaned, how and when. The buyer of the potatoes may request a record of cleaning activities.
- Preferably use dry cleaning methods and in any case start with them. Only if no suitable dry cleaning method is available, or not sufficient for complete cleaning, should water be used. When using complementary wet cleaning, an acceptable method of collecting water and disposing of it appropriately must be used to avoid dispersing waste water into the environment.
- Care should be taken to minimise re-distribution of CIPC. Loose materials should be removed promptly, by vacuuming. Sweeping and brushing generate dust, which risks re-distribution.
- Cleaning must be carried out from top to bottom (i.e. roof to floor).
- CIPC is only slightly volatile. Volatilisation will contribute to removal of CIPC, but over longer periods of time. When the store is not in use for potato storage, doors and hatches should be left open to allow for continuous refreshment.
- Underground cleaned ducts should also have a constant movement of air after cleaning, either by running fans or by natural draft. Low airspeed is sufficient.
- Where possible, first remove loose waste material by dry cleaning and then move store hardware (boxes, above ground ducts, etc.) outside so weather action (sun, rain, wind, temperature) can also contribute to CIPC removal.
- Cleaning efforts should focus in positions of highest contamination, like plenum and fans (see section 2.1 and 6).
European guidelinesCleaning guidelines for reducing chlorpropham (CIPC) from potato stores and equipment
Figure 1: Concrete floor of main duct before cleaning
Figure 2: Main duct after cleaning
Minimising disease risk
Ventilation and convection currents, caused by respiration heat from the crop, will circulate dust containing disease spores throughout the store. Cross-contamination of potato stocks is therefore inevitable. Major dust movement and dispersal also occurs when store activity, e.g. forklift truck movement, stirs up dust on the floor. The resultant dust cloud will settle on top of the crop, where the risk of condensation needed for spore germination is greatest.
Clearing dust and stray tubers from storage areas and ducts will normally remove the majority of residue or disease inoculum present. This is usually adequate for most ware crops.
- Use a vacuum for removing loose dust
- If wet rots have been a problem in previous seasons, pay attention to particularly affected areas of the store and boxes.
When should I use disinfectant to clean my store?
If total removal of viable disease spores is required, e.g. for high‑health crops, disinfectant can be used. This is particularly relevant in stores where bacterial soft rotting or damage-related fungal diseases such as dry rot have occurred. Most disinfectants will not work without prior cleaning and removal of dust and debris as they are readily deactivated by organic matter.
Make sure any disinfectant used on parts of the store that are in contact with crops are food-safe and acceptable to your intended market.
Soft rot in box store
Store hygiene checklist
✔ Remove all dust and debris as soon as store is empty, in preparation for following storage season
✔ Vacuum dust – don’t sweep as it just relocates most of the dust
✔ If required, disinfect only after cleaning