Home Garden Irish Potato Production in West Virginia

Transcription

1 Home Garden Irish Potato Production in West Virginia HR Scott, Lewis Jett and John Porter The potato (Solanum tuberosum) is a cool-season vegetable which was under cultivation in the Andes Mountains for more than 6000 years before the Spanish came to South America in the 16 th century. Today, the potato is the most important vegetable food crop throughout the world. In West Virginia, the Irish potato has been a versatile garden vegetable crop for many generations. A member of the nightshade family (Solanaceae), the Irish potato is closely related to tomatoes (S. lycopersicum), peppers, eggplants, tomatillos and tobacco. Potatoes can be grown in West Virginia with optimal amounts of sunlight, temperature, water, and the proper soil type. An ideal soil for potatoes is deep, well drained, fertile and relatively rock- and debris-free. Soil Fertility: Organic matter in the soil improves soil structure, enable roots of potato plants to penetrate the soil more readily, improves water retention, provides food energy for the growth of desirable soil micro-organisms, and supplies plant nutrients. Avoid using fresh or raw manure as a source of organic matter since this can promote diseases such as scab and Rhizoctonia. If your garden is low in organic matter, compost can be applied or a winter cover crop (e.g., rye, vetch) can be

2 planted the previous fall and mowed and tilled in the soil 2-3 weeks before the potatoes are planted in the spring. For potato production, the soil ph should be to avoid scab on the potatoes. If the garden has a history of scab, scab-resistant potato varieties should be grown (Table 1). Newer varieties bred for scab resistance can be grown in soil ph of 6.0 to 6.5. Fertilizer applications ideally should be applied in continuous band two to three inches to each side and slightly below the seed piece at planting. Many gardeners broadcast fertilizer before tilling and then cultivate or turn under. For nitrogen fertilization on most garden soils, a general purpose fertilizer such as can be used, and approximately lbs./100 ft 2 can be applied. A second application of fertilizer (e.g., 2.5 lbs./100 ft ) is normally applied 4-5 weeks after planting (at first hilling) as a side-dress on sandy or sandy loam soils. If compost or a cover crop with a nitrogenfixing legume such as hairy vetch or clover is used or tilled in prior to planting, the fertilizer rate can be reduced by approximately 30%. Total phosphorus and potassium applications should be based upon a current soil test, and the amount to apply based upon the recommendations from the soil test. Variety Selection: There are a wide diversity of potato varieties which vary in yield, size, shape, flavor, skin color, flesh color and storability. Whatever variety chosen, the seedstock should be certified, diseasefree seed. Certified seed is grown under rigid rules and carefully inspected by state authorities. Suggested varieties for home garden production are listed in Table 1. Potato varieties fall into three general types, which have different uses in the kitchen. Starchy Potatoes are high in starch and have a low-moisture, fluffy interior. These potatoes are best used for boiling, baking, frying, and mashing but don t hold their shape well. The classic Russet or Idaho potato are common starchy varieties. Waxy potatoes are low in starch and have a creamy but firm texture. These varieties are best used for salads, casseroles, and any dish you want the potato to hold shape. Fingerling potatoes are common waxy varieties. Any variety of potato harvested as a new potato is also waxy in texture

3 All-purpose potatoes can function as both starchy and waxy in dishes, as they have medium starch content. Yukon Gold and Kennebec are common all-purpose potato varieties. Table 1. Suggested varieties of Irish potatoes for home garden production in West Virginia. Variety/Cultivar Season Scab resistance Description (days) Austrian Crescent good Fingerling potato; Yellow skin and flesh. Chieftain Smooth red skin; white flesh Colorado Rose Smooth red skin; white flesh Desiree Red skin with yellow flesh German Butterball Yellow skin and yellow flesh Kennebec susceptible Standard variety with white skin and white flesh Purple Majesty Purple skin; purple flesh; High antioxidant levels Red Gold Red skin with yellow flesh Red Norland good Early with red skin and white flesh Red Pontiac fair Red skin; white flesh Yukon Gold susceptible Yellow flesh and skin; Early Planting: Potatoes can be planted from March 30-June 5 in most regions of West Virginia. At planting, the soil should be moist, but not excessively wet. Row widths are generally 30 to 36 inches and in-row seed placing from 7 to 12 inches. Planting depth is normally between 3 to 5 inches deep with a covering of 2 to 4 inches of soil. Early-season potatoes can be planted on black plastic mulch and raised beds. The plastic mulch warms the soil resulting in faster growth. A drip irrigation tube or soaker hose can be placed under the plastic to water the crop. The seed pieces can be planted using a bulb planter to make a 4 inch deep hole. No hilling is performed since the plants are growing on a 6-8 inch-high raised bed. The plastic mulch can be biodegradable or if it isn t, it can be cut and removed prior to digging the crop. In many small gardens with limited space, growers can grow potatoes in a small area using a potato tower or mulch system. This includes building a box or using a barrel (or other similar setup) that allows for soil or straw to be added around the plant throughout the growing season.

4 This method takes advantage of the fact that a potato is a tuber, or a modified stem. As the stem is covered, it allows potatoes to develop along it. It is important, however, not to cover too much of the plant since it requires foliage to produce enough energy to form the potatoes. Cultivation: Potatoes should be hilled at least once to support the plants and keep soil over the tubers so they will not get sun burned and develop a green color. The first hilling is done when the plants are inches tall and they can be hilled again 3-4 weeks later. Do not cultivate deep because this could damage potato roots and slow growth. Control of weeds can be done by shallow and frequent cultivation or hand pulling. After 30 to 40 days of plant growth, cultivation is stopped so that plant roots and tubers will not get damaged. Pest Management: For insect and disease control, products are available for use on potatoes in local garden or feed supply stores. The product label will provide specific information on rate and timing of application. Insect such as flea beetles, leafhoppers, aphids and Colorado potato beetles are common pests of Irish potatoes. Light-weight floating row covers can be used to reduce insect problems. In addition, organic products containing spinosad will control the larvae of Colorado potato beetles. Late blight and early blight are potentially severe foliar diseases which can be effectively controlled with fungicides. Mulching the potatoes with leaves, shredded newspaper, plastic, or other mulch will reduce splashing of soil on bottom leaves and help reduce fungal diseases such as early and late blight. For ground that was previously in sod, wireworms, white grubs, and other soil insects may be present and can damage the potatoes. Contact your local extension office for more detailed recommendations for control of pests. Integrated Pest Management: Many pests of Irish potatoes can be reduced or eliminated with integrated pest management techniques. Crop rotation should be practiced to reduce insect pests and diseases. The optimal rotation would be to avoid planting potatoes or any other Solanaceae family members for at least three years in the same area of the garden.

5 Harvesting and Storage: New potatoes can be harvested at flowering by reaching into the hill and gently removing potatoes without damaging the plant. These fresh potatoes have tender skins and are not stored. The main crop of potatoes are dug two weeks after the vines die to get the highest yield and best storage. The skins have had time to set and reduces peeling, bruising and rot during storage. Upon harvesting the potatoes, they should be brushed dry and not washed, and immediately placed in a dark place or be covered with a breathable fabric. Also, there should be good air movement among the potatoes. The temperature in the curing area should be 60 to 65 F with 85% humidity or higher for ten days. Once the tubers are cured, they can be moved to a cool, (40-45 F) dark storage area with high humidity such as a root cellar or basement. Avoid storing potatoes with apples which emit ethylene gas that causes early sprouting. Programs and activities offered by the West Virginia University Extension Service are available to all persons without regard to race, color, sex, disability, religion, age, veteran status. Political beliefs, sexual orientation, national origin and marital or family status. Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Dept. Of Agriculture, Director, Cooperative Extension Service, West Virginia University AG12-137