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:
- All surfaces need to be cleaned, from the top down*. Concentrate on contamination hotspots e.g. the tunnel in bulk stores and around the application port and air handling unit (where used) in box stores. Washing with water is not recommended.
- On exposed foam insulation, be gentle with a brush attachment on the vacuum. A chisel may be more useful on the floor of the main duct (Figure 2).
- Once cleaned, leave the store as open as possible, to allow air movement around the store.
- Boxes, and any equipment that can be moved, e.g. A-frames or half-rounds should be put outside to air and be exposed to UV radiation. Space boxes out so that exposure to light is maximised, while ensuring that they don’t cause a health and safety hazard.
- Keep a record of when and how you cleaned your store. This evidence will likely prove valuable in demonstrating that the industry is taking a proactive approach towards keeping residues down.
*Treat deposits as you would any other plant protection product–wear appropriate PPE and dispose of waste appropriately.
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