Potato Production: Seed, Blight & Storage (USA & Canada)

Updated 2026-07-11 · Crop guides

Potatoes are a high-value crop from Idaho and Washington to Maine, PEI, Manitoba and Alberta — and a demanding one. The whole season turns on three things: clean certified seed, keeping the tubers covered and evenly watered, and staying ahead of late blight and the Colorado potato beetle.

Start with certified seed

Potatoes are propagated vegetatively, so any virus or disease in the seed multiplies in your field. Always plant certified seed potatoes — never saved table stock — to keep out virus (PVY), late blight, bacterial ring rot and blackleg.

• Cut seed to blocky 1.5–2 oz (40–55 g) pieces with 1–2 eyes each; suberise (heal) the cut surfaces in warm, humid, airy conditions for a few days before planting, or plant small whole seed.
• Choose varieties for your market (fresh, chip, or process/fry) and for disease resistance — scab and late-blight tolerance vary widely.

Plant, hill and water for smooth tubers

Plant when soil reaches 45–55°F (7–13°C), about 3–4 inches deep and 8–12 inches apart in rows 30–36 inches wide.

• Hill (earth up) as plants grow to keep tubers covered — exposed tubers turn green (solanine) and sunscald, and hilling also buries small weeds.
• Even moisture is critical: irregular watering causes growth cracks, knobs and hollow heart. Keep soil consistently moist through tuber bulking, then taper before harvest to set skins.
• Manage scab with pH and water: common scab is worse in dry soil and above pH ~5.5 — keep tuber initiation well-watered and avoid over-liming potato ground.

Late blight and early blight

Late blight (Phytophthora infestans) — the Irish-famine pathogen — can destroy a field in days under cool, wet, humid weather. It is a community disease: your crop and your neighbour’s depend on shared vigilance.

• Destroy cull piles and volunteer potatoes — they are the main overwintering source.
• Grow tolerant varieties, follow late-blight forecasting (disease severity value) networks, and run a protectant fungicide program when risk is high; rotate fungicide chemistry.
• Early blight (Alternaria) is a warm-weather, older-foliage disease managed with rotation, balanced nitrogen and fungicide as needed.

Colorado potato beetle — rotate and rotate chemistry

The Colorado potato beetle defoliates fast and is famous for shrugging off insecticides. Beat it with IPM, not a single product:

• Rotate fields as far as practical from last year’s potatoes — overwintered adults walk to the nearest crop, so distance genuinely reduces pressure.
• Scout and treat larvae on threshold with rotating modes of action (e.g. spinosad, Bt tenebrionis, novel chemistry) — never the same class twice in a season.
• Encourage predators and use straw mulch/trap cropping in smaller plantings.

Cure and store

After harvest, cure tubers at 50–60°F (10–15°C) and high humidity for 10–14 days to heal skins and cuts. Then hold long-term in the dark with good airflow: 40–45°F (4–7°C) for fresh/table stock, and warmer 48–50°F (9–10°C) for chip/process potatoes (cold storage turns sugars and darkens fries). Never store potatoes with apples or near ethylene sources.