3/22/04

Contacts:
James Romer, Horticulture, (515) 294-2336, jromer@iastate.edu
Jean McGuire, Continuing Education and Communication Services, (515) 294-7033, jmcguire@iastate.edu

Yard and Garden Column for the Week Beginning March 26, 2004

Dr. Grow-It-All Answers a Spring Question

By James Romer
Extension Horticulture Specialist
Iowa State University

Dear Dr. Grow-It-All:

It's hard to believe that another St. Patrick's Day has come and gone! The wearing o' the green always gets me in the mood to get out in the garden and plant something. I'm really quite fond of potatoes, but I don't know what to do. Dr. Grow-It-All, can you help me?
B'gosh and B'gorrah in Decorah

Dear B'gosh and B'gorrah:
It's no Blarney that one of the most popular vegetables grown in the home garden is the "Irish" potato. Actually, the potato was introduced to Ireland from South America in the 16th century. Eventually, the potato became a staple in the diets of the Irish. The potato became so important that when late blight disease attacked the crop in the 1840s, widespread famine resulted.

When selecting potatoes for planting don't depend on the luck of the Irish alone. Buy certified disease-free potatoes from a reliable nursery or garden center. Certified seed potatoes are free of several serious seed-borne diseases and produce the best crops (excellent quality and high yields). Potatoes purchased at supermarkets may have been treated to prevent sprouting. Homegrown potatoes saved from the previous year's harvest may carry undetectable diseases.
Potatoes prefer loose, fertile, slightly acidic soils. Don't apply large amounts of organic matter, such as manure, to the soil where potatoes are to be grown. The addition of organic matter may increase the occurrence of potato scab.

In preparation for planting, large potatoes should be cut into sections or pieces. Each piece should contain 1 or 2 "eyes" (buds). Small potatoes may be planted whole. Decay of the seed piece may be a problem in cool, wet soils. This problem may be prevented by treating the cut seed pieces with a fungicide or by storing them at a temperature of 60 to 70 degrees Fahrenheit and 85 percent relative humidity for several days. These storage conditions allow the cut surfaces of the seed pieces to heal or callus over before they are planted.

Potatoes should be planted as soon as the ground can be worked in the spring. This is typically late March or early April in the central areas of the state, one week earlier in southern Iowa and a week later in northern Iowa. Seed pieces and small whole potatoes should be spaced 1 foot apart in a furrow 4 inches deep. Rows should be spaced 24 to 36 inches apart.

Some suggested potato cultivars for Iowa include:

Irish Cobbler is an early maturing white variety. Potato tubers have a blocky look with sunken eyes. Irish Cobbler possesses excellent table quality. However, it is very susceptible to scab.

Kennebec is a late maturing white variety that produces block-shaped tubers with shallow eyes. Kennebec has excellent cooking quality.

Norland is an early maturing red variety that yields oblong, smooth potatoes with shallow eyes. Norland is best used for boiling or mashing. It is fair when baked.

Red Pontiac is a late maturing red variety. Potatoes are oblong in shape and possess deep eyes. A high yield can be expected with many large tubers. Storage quality is very good while table quality is only fair.

Russet Norkotah is a late season russet variety that produces blocky, oblong potatoes. It is an excellent baking potato. Russet Norkotah has replaced Norgold Russet on the suggested potato variety list as Russet Norkotah produces larger sized tubers and higher yields. It also adapts well to Iowa growing conditions.

Superior is a mid-season white variety with round to oblong tubers and medium deep eyes. The scab resistant potatoes are very good when baked, boiled or mashed.

Yukon Gold is a midseason yellow-fleshed "pot o' gold" variety. They are excellent baked, boiled, or mashed. The potatoes also store well.
With the right varieties, buying certified disease free potatoes and proper planting location and conditions I'm sure your Irish (potato) eyes will be smiling.

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Editors: There is no photo for this week's column.

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