Potatoes Essay, Research Paper

PLANTING

It is possible to grow potatoes from true seeds produced in the flower of the potato plant, but home gardeners can obtain better results growing plants from whole tubers, called seed tubers, or from pieces of a tuber with a least one lateral bud or eye, called seed pieces. This practice is called vegetative propagation. For best production, seed tubers and seed pieces should weigh at least 1.5 ounces.

Unfortunately, plant parts are more likely to accumulate and harbor diseases, especially viruses, than are true seeds. To avoid this problem, commercial potato growers usually plant certified seed. Certified seed potatoes have been inspected by a certification agency at least twice during the growing season to ensure that any disease present is within strict tolerances. Home gardeners should also plant certified seed in their gardens. Potatoes from the supermarket may carry viral diseases or be treated with a sprout inhibitor that will prevent the tubers from germinating.

Many garden stores carry certified seed potatoes, so seed should not be difficult to find. You may have to consult a local Extension agent to find a source for some exotic varieties. Buy your seed in early spring to be sure you get what you need. You will need 8 to 10 pounds of seed potatoes for each 100 feet of row.

Potatoes germinate and emerge best when soil temperatures are more than 50 degrees Fahrenheit. Plant seed 4 to 5 inches deep in rows about 10 inches apart and 30 to 36 inches wide. Although potatoes can be planted on flat ground, it is better to form a hill up around the plant. Hills provide room for developing tubers to expand and prevent greening by the sun. Hilling is also important for drainage. Potato hills can be formed at planting time by mounding dirt up around the seed piece. Or they can be formed after the plants are up. It is best to hill within 4 weeks of planting.

Be sure to have good soil moisture at planting. If soil moisture is inadequate, lightly irrigate before planting to ensure rapid, early plant growth. Extremely wet soils, however, will increase the possibilities of seed piece rot.

ROTATION

Do not plant potatoes in the same area of the garden each year; it may predispose the crop to disease and insect problems.

IRRIGATION

Potatoes require good soil moisture at all stages of growth. An uneven water supply can influence the development of knobs or growth cracks on tubers. Potato plants do not use much water early of late in the season, but they need a lot of water when the foliage is fully developed (late June through July).

Potatoes have a relatively shallow, sparse root system. Plants take up most water from the top foot of soil. Irrigate when the soil in this region begins to dry. Check the soil at the plant root zone. If the soil looks and feels moist and forms a wet ball when squeezed by hand, soil moisture is adequate. If the soil forms a fragile ball when squeezed, apply a half inch of irrigation water. Dry, loose, crumbly or powdery soil at the root zone requires a 1-inch irrigation for coarse-textured soils to 2 inches for fine-textured soils. Heavier soils need furrow irrigation every 5 to 7 days, but more frequent irrigations may be necessary on sandy soils. Sprinkler-irrigated potatoes benefit from light, frequent (3 to 5 days) water applications, especially when temperatures are higher than 80 degrees Fahrenheit. For example, sprinkling a 500-square-foot area for 25 minutes will apply approximately 1 inch of irrigation water. To check the water application, place a measuring can made from a common tin can near the plants.

Once the plants begin to yellow and the lower leaves start dying, reduce the irrigation rate. Too much water late in the season may predispose the tubers to rot. The crop should be dried down to mature the tubers and to set the skin to reduce bruising. The vines should be dead for 2 to 3 weeks prior to harvest. Potatoes cured by withholding water late in the growing season will store better.

FERTILIZATION

Potatoes respond well to optimal levels of soil nutrients. Be careful not to over fertilize, especially with nitrogen (N). Excessive N will cause plants to produce too much foliage, and delay tuber growth. The best method to determine how much fertilizer to apply is to test the soil.

Broadcast fertilizer when forming hills prior to planting. Apply fertilizer uniformly across the garden area, and incorporate into the top 3 to 4 inches with a rake. Choose a balanced fertilizer, such as 5-10-10, 10-10-10, 16-20-0, or an organic form, such as compost. Potatoes will use about 0.38 pounds of N for every 100 square feet of garden space. If using 16-20-0, for example, the fertilizer contains 16 percent N, 20 percent phosphorous(P2O5) and 0 percent potassium (K2O). Therefore, for a 100 square foot area, apply 2.4 pounds (0.38 divided by 0.16=2.4) of material evenly. It is best to apply about half the fertilizer before planting. Apply the other half about late June. Use only thoroughly decomposed or composted sources of manure because fresh manure can increase common scab occurrence. If leaves begin to turn yellow before mid-season, add a small amount of N fertilizer to the side of the hill and incorporate with a rake or irrigation water.

PEST CONTROL

A number of weed, insect, and disease pests can affect potatoes in a home garden. Examine potato plants regularly to detect pest outbreaks before they become major problems. Many pests can be controlled without using chemicals, especially if detected early. In most cases, disease control will not be necessary in the home garden.

WEEDS–Most potato varieties produce relatively large plants, however, weeds can reduce yields by competing with potatoes for water, nutrients, and light. The most critical period for weed competition is during early growth, from emergence until plants are approximately 12 inches tall. Control common annual weeds such as redroot pigweed, lambsquarters, and nightshade by hoeing or pulling during the hilling operation. Cultivation can actually spread troublesome weeds, such as thistle and quackgrass. Once plants reach their full size, cultivation must be shallow to avoid pruning potato roots near the soil surface.

INSECTS–The most troublesome insect in the home garden is the Colorado Potato Beetle . You will begin to see adult CPB as soon as the potatoes emerge.

The adult beetles, which overwintered in the soil, emerge in the spring to lay eggs on susceptible host plants. Adult beetles have round, hard, yellow wings with ten black stripes. The eggs hatch, producing larvae which do the most damage to potato plants. Larval feeding defoliates the plants. Larvae are brick-red with two rows of black spots on each side.

To control the adult beetles, hand pick them from the potato plants before they lay their eggs on the undersides of the leaves. The eggs are a bright orange-yellow color. If the eggs hatch, pesticides are available to kill the larvae.

DISEASES–Potatoes are affected by a long list of disease problems. Fortunately, most of them do not occur in the home garden. Many common seed-borne potato diseases can be avoided simply by purchasing and planting certified seed. Included is a brief description of diseases that home gardeners frequently encounter and suggestions for control. Note that the control measures include management practices to observe for the entire season, even before planting. It is best to avoid conditions that favor disease development.

Common scab can be a problem on tubers harvested form the home garden. This disease is caused by a bacterium and is characterized by small (generally 5 to 8 mm diameter) light-tan to brown lesions resembling small scabs on the tuber skin. Dry conditions enhance scab development, especially early in the growing season. Proper water management should greatly reduce the potential for scab development. Scab can be particularly severe in soils with a high organic matter content. Avoid planting potatoes in soil recently treated with animal manure. In gardens where scab has been a problem in the past, consider planting a scab-resistant variety. Scab is strictly an appearance problem and does not affect potato quality.

Early blight is caused by a fungus and characterized by circular, brown to black lesions on the leaves. Lesion shape may change form circular to angular if a large leaf vein stops the fungi progression. Early blight lesions have a bulls eye appearance. Lesions usually appear on the lower leaves first and may then progress upwards on the plant until all of the foliage is affected and the plant dies prematurely.

Stressed plants are more susceptible to early blight than health plants. Maintaining proper soil fertility and good water management will help prevent early blight