The best way to store fresh potatoes: plan for the intended market
Preserving potatoes for long term storage, or storing raw potatoes, starts with the lot rather than the room. Match variety, maturity, lot condition and intended market to the storage plan. Keep potatoes for eating separate from material you retain for planting.
Potato storage time: match the lot to the planned holding period
Rub the skin gently when assessing maturity: skin that rubs off easily indicates incomplete skin set. Mature, late-season varieties generally keep better than thin-skinned and early types. Select lots for the planned holding period.
Cure harvested potatoes in darkness with ventilation, moderate temperature and high humidity. Then lower the temperature for table-potato holding. Treat curing and longer storage as separate stages.
After harvest, dry cleaned potatoes fully before storage. Brush loose sandy soil away; rinsed tubers from sticky clay need thorough drying. Use perforated bags or ventilated containers so air can circulate around table potatoes.
Choose a dark store with suitable temperature and ventilation. Light causes greening, so arrange inspection and access so stock is not routinely exposed to light.
Very low temperatures increase sugar accumulation, while higher temperatures favour decay, sprouting and shrivelling. Set the temperature for the intended use and the condition of the lot.
Move harvested potatoes promptly to a cool warehouse to limit potato tuber moth damage. When planning intake, weigh this local pest risk alongside the buyer’s storage requirements.
To stop potatoes from sprouting, check variety, maturity, lot age and the measured storage conditions, because variety and temperature affect keeping quality. A chemical sprout treatment needs a Maltese authorisation; see the authorisation route.
Light exposure causes chlorophyll production and green colour. Greening can also indicate solanine. Discard excessively green tubers.
Stored potatoes: keep pest observations tied to the actual lot
Put the lot number and store location on each pest-inspection note. Photograph the affected tissue and keep any insect you recover.
Potato tuber moth makes irregular internal galleries; storage rots have different symptoms.
Discard tubers with wounds, pests or disease before storage. Avoid injury during harvest, and record the lot’s condition at receipt before combining material from different origins.
Remove affected material, limit handling injury and maintain cool-air circulation and ventilation in seed-potato stores. Record completed work against the lot and the inspection date.
For worker safety, Maltese chemical-agent rules require assessment of hazardous chemical exposure, including combinations and maintenance circumstances. Ask the competent assessor for the controls before you assign anyone a treatment or recovery task.
Distinguish dry rot, gangrene and soft rot
Fusarium dry rot starts at bruises or cuts and spreads inward. Tubers develop sunken, wrinkled areas. The internal tissue becomes light brown to black, and cavities may contain white, yellow or pink mould. Inspect damaged intake lots before deciding where to place them in storage.
Gangrene produces dark depressions that enlarge into irregular cavities. Small black spheroidal bodies, called pycnidia, may be present. The pathogen persists in soil or seed material. Limit handling wounds and remove infected residues promptly.
Bacterial soft rot makes tissue water-soaked and macerated, later spreading through the tuber with a foul smell. Infection can remain latent in seed tubers before sowing. In your inspection notes keep soft, wet decay separate from dry pits and moth galleries, and send representative material for diagnosis.
Black dot shows as fine black blemishes on the tuber skin, formed by fungal sclerotia. Colletotrichum coccodes affects underground parts, including roots and stolons, and can also infect stems. When comparing affected seed lots, check these structures alongside skin quality.
Label the external photograph, the cut surface and any recovered insect with the same sample identity. Note separately whether damage is bruising seen at receipt or decay that developed later.
Keep your spray records in one place. Free to start.
Buying seed potatoes: specify the planting lot before choosing a supplier
Healthy, certified seed potatoes with a clear lot reference are the planting material. Buy the variety you need, and compare the supplier’s consignment with your planting plan. A mini tuber offer should name the variety and the consignment; compare mini tubers as planting material, not as if they were an ordinary retail potato lot.
Search Malta’s organic reproductive-material database for organic potato seeds. Compare species, variety, supplier contact, delivery area, availability date and the relevant control authority or body.
If the required organic variety is unavailable, contact the Agriculture Directorate and your organic control body before ordering non-organic material. Keep the written outcome linked to the planting lot.
Plant-passport information and the supplier’s commercial description answer different questions. The passport identifies the plant material and responsible operator for traceability; the purchasing agreement describes the variety, lot and material being supplied. Keep both with the actual consignment.
Plant passport meaning: read the identity on your planting material
A plant passport records the material’s traceable plant-health identity for EU business-to-business trade. The EU plant-health framework covers it. Match the botanical name, operator reference, traceability code and origin on the passport to the delivered lot, and keep it with the supplier’s documents.
Read the square or rectangular passport with the EU flag and Plant Passport heading. The lettered fields identify the botanical name, registered operator, traceability code and country of origin or production. Keep any combined certification label intact with the consignment. When you add your own stock code, keep the original passport reference and write the farm’s shorter code beside the supplier’s traceability identity, so both can be found.
Passports are issued by the National Plant Protection Organization or businesses officially registered and authorised by it. Keep the issuing operator’s identity with the consignment.
Insecticides for stored grain: identify the pest and treatment target first
Before choosing a treatment, identify the insect, the lot and the treatment target. Plan the treatment of grain, of the empty store and of handling equipment separately.
For insecticides for stored grain pest control, sanitation and temperature management limit carryover into incoming grain.
Match the commercial product and intended storage use through the official authorisation route. Compare the product’s identity, formulation and crop or use description with the treatment you plan.
Inspect grain for hollowed kernels, beetle exit holes and webbing from moth larvae. Keep samples that show these signs, with the store location and lot identity.
Remove old grain and check fines, broken kernels and chaff, including accumulations beneath slotted flooring. These residues shelter insects that infest new lots.
Clean old grain from augers and transport equipment as well as the visible store floor. Residues in the handling system can reinfest incoming grain.
Seasonal temperature changes affect their movement within the grain mass, so compare store temperatures and sampling locations when monitoring.
Some immature grain insects remain concealed inside kernels, so examine hollowed kernels and exit holes as well as visible insects.
Next step
Inspect each lot’s condition and intended use. Use the Malta authorisation route for treatments and the organic-material database for planting stock.