Why Have The Tubers Of My Potatoes Developed Poorly?

Do the potatoes have green patches on their skin?

Do the potatoes have brown or black spots or patches on skin?

Do the potatoes have rough, corky spots on the skin?

Do the potatoes have gray to black areas in the flesh, centers may be hollow?

Is the soil in which you're growing potatoes wet and poorly draining?

Was the weather in this growing season unusually hot or were there sudden frosts before harvesting potatoes?

Have the potato tubers suffered a mechanical injury during harvest?

Are the potatoes riddled with tunnels and holes?

Are the tunnels in the potatoes browned, silk-lined?

Have the potato tubers grown small?

Green patches on potato skin is caused by light exposure. A toxic substance called solanine may develop in green skin. To prevent it you should cover potatoes by 2 inches of soil so there is no light exposure.

Brown or black spots or patches on skin is a fungal disease - Scurf. You should peel off affected spots before using tubers. If you plant affected tubers, newly developed plants will produce small tubers susceptible to rot.

Rough, corky spots on the potatoes skin is a fungal disease - Scab. You should peel off affected spots before using tubers. You can prevent scab by keeping soil pH below 5.5 and plant one of the more resistant cultivars like Superior, Beltsville, Norland or Onoway.

Potatoes grown in wet, poorly drained soil often grow too fast and may develop a discolored or hollow area in the center. To prevent this, try to keep the soil moist but not flooded or soggy.

Extremely hot weather or sudden cold snaps can cause discolored or hollow area in the center of the potato. Prevent extreme temperatures by covering potatoes well with soil or mulch.

Mechanical injuries, like bruising, can appear as discolored areas on the tubers. Handle tubers gently during harvest and while storing the potatoes.

Phosphorus or potassium deficiency can cause spots or patches of dark flesh on potatoes. A soil test is the only way to be sure if there are any deficiencies in the soil. Use fertilizer with a deficient nutrient to amend the soil.

Tuberworms cause browned, silk-lined tunnels in potatoes. Tuberworms are pinkish-white larvae that feed in stems, leaves and mostly in tubers. Destroy infected tubers and plants. You can prevent them by keeping tubers hilled with soil and by removing the dead vines before digging tubers.

Wireworms cause small holes in potatoes. Wireworms are yellow to reddish-brown, hard and segmented larvae. Damage by wireworms usually occurs late in the season. You can control wireworms by introducing parasitic nematodes into the soil.

Small potatoes may be caused by poor growing conditions or by calcium deficiency. Potatoes require deeply worked, well-drained soil with lots of organic matter, and a pH between 5.0 and 6.8. Soil rich in nitrogen, phosphorus, potassium, calcium, and sulfur is needed for good growth. Also, the soil needs to be constantly moist, but not flooded.

Various bacterial and fungal rots may have affected your potatoes while in storage. To prevent bacterial and fungal diseases in storage sort out any bruised, cut or diseased potatoes from the healthy batch. Keep healthy potatoes in a cool and dry place.