Irish potatoes

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INTRODUCTION

Irish potatoes are a starchy tuber crop from the perennial solamun tubersum of the solsnaceae family. They are mainly grown in the cool highland areas as a food crop as well as a vegetable. Potatoes are the world's most widely grown tuber crop and the fourth largest crop in terms of fresh produce (after rice, wheat, and maize).

LOCAL NAMES

Luganda – obummonde

Luo – layata manu

Runyakitara – emonde

Kiswahili - viazi

CLIMATE Irish potatoes grow well in areas that receive regular rainfall and have a cool climate with temperatures ranging 10 - 23. Irish potatoes grow best in mild degrees Celsius with abundant rainfall 900-1400mm per annum. The major growing areas include Kasese, Mbale and areas around mount Rwenzori. This is because of the low temperatures that prevail there. WHICH VARIETIES CAN BE PLANTED IN OTHER WARMER AREAS?

SOIL Irish Potatoes do best in a loose, well-drained, slightly acid soil. Poorly drained soils often cause poor stands and low yields. Heavy soils can cause tubers to be small and rough.

FOOD VALUE One raw and unpeeled Irish potato weighing 100g, with an energy value of 80kcal (320kj) contains Carbohydrates (19g) in form of Sugar (15g) and Starch (2.2g). It also contains Fat (0.1g), Protein (2g) and water (75g). In addition, it contains Vitamin B1 (0.08mg), Vitamin B2 (0.03mg), Vitamin B (3 1.1mg), Vitamin B6 (0.25) mg, Vitamin C (20mg) ,Calcium (12 mg), Iron (1.8mg), Magnesium (23mg), Phosphorus 57mg), Potassium (421mg) and Sodium (6mg).

VARIETIES IN UGANDA Irish potato varieties grown include; Rutuku, Victoria, Kisoro, NAKPOT 1, NAKPOT 2, NAKPOT 3, Kruzer and Sangema. Victoria is the most commercially grown variety. It is high yielding, early maturing and tolerant to bacterial wilt.

SITE LOCATION

A good site for irish potato growing should be hilly with well drained fertile soils.

Before planting, clear the land of all bush and tree trunks, deep plough and dig again after 2 weeks before the start of the rains to loosen the soil and remove all weeds.

SEED PREPARATION

Irish potatoes are grown from pieces of the potato tuber. This seed piece provides food for the plant until it develops a root system. The seed potato contains buds or "eyes" which sprout and grow into plants. Good seed is characterized by having at least one good “eye”.

To obtain good seed, it is advisable to acquire seeds from a certified source, research station or established irish potato seed producers.

Alternatively, you can opt to make your own seed. To do this, select mature disease free tubers without any damage. Mix them with herbs like neem leaves or lantana camara for prevention of pests. After, keep them under a shade until they sprout before planting.

Also you can take the potato tubers out in the field or keep in a warm place for about 15 - 20 days before planting. Let them sprout at a temperature of 15 - 20ºC for 10 - 15 days, Diseased potato tubers will rot in high temperatures. Remove the rotten ones and dispose of them properly, and properly select the healthy sprouted potatoes as planting materials.

GARDEN PREPARATION

•Choose land with well drained sandy loamy soils. •Clear the bush and plough the land to soften it. •Dig for the 2nd time after 2 weeks and make ridges. Note that adequate tilling and drainage are essential so as to increase the oxygen supply in the soil which is a vital ingredient for Irish Potato growth Irish potatoes grow best on raised beds. This can be done in two ways; during initial land preparation or immediately after planting. Adoption of raised beds leads to improvements in soil moisture, temperature, adequate aeration and drainage.

Avoid planting in water logged areas especially since this will lead to the seeds rotting.

FERTILIZER APPLICATION

Irish potatoes need adequate fertilizers in the early season, apply most of the fertilizer just before planting. The fertilizer should not touch the seed piece to avoid rotting. To apply the fertilizer, flatten the beds so they are 6 to 8 inches high and 10 to 12 inches wide.

PLANTING & SPACING

Make ridges of 15-30cm (6inches -12inches) high, spaced 2ft (60 cm) apart. Plant sprouted big-size healthy tubers spaced at 30cm in rows, 5-7.5cm deep for big size tubers and small size tubers for smaller size tuber yield.

In case of single rows, leave 2ft (60cm) cm to 3 ft (90cm) apart and incase of double rows leave a space of 6ft (180 cm)to the next row.

WEEDING

Weed control reduces yield loss due to competition for moisture, nutrients and light and at the same time act as alternate host for pests and diseases. For this reason, weed when the crop is about 10 cm high and second weeding at 20 – 25 cm high. Early weeding is preferred to reduce contact between plants to avoid spread of viruses such as potato virus.

Harvested weeds should not be thrown away but rather put into ridges and covered with soil for additional manure.

Cut the bushes around the garden to scare away pests especially rats.

COMMON DISEASES: PREVENTION & MANAGEMENT

DISEASE 1: EARLY BLIGHT

Early blight (EB) is a disease of potato caused by the fungus Alternaria solani. It is found wherever potatoes are grown. The disease primarily affects leaves and stems during the early stages of growth, and if left uncontrolled, can result in considerable defoliation and enhance the chance for tuber infection. It may lead to considerable reduction in yield.

It is characterized with the formation of lesions, withering, and death of parts that occurs before plants mature. See Appendix 1: Picture 1.

CAUSES

Fungal

SYMPTOMS •Brown circular "burn-like" spots on leaves •Stems lose color. •Young plants maybe destroyed before flowering. •Dry spots on tubers

PREVENTION

•Use clean disease free seeds. •Mulch garden to minimize soil splash which spreads fungus. •Use crop rotation •Use adequate fertilizers in order to keep the plants grow strongly (weaker plants are easily affected). •Remove plant residues immediately after harvesting. •Plant resistant varieties

TREATMENT

•Eradicate weeds •Remove and burn the diseased plants •Allow tubers to mature fully before harvesting. •Remove and destroy the affected plants by burning or deep burying.

Note: infected tubers are unfit for human consumption, because of the poor tests and also the nutrients are destroyed by the disease.

DISEASE 2: LEAF BLIGHT

It’s a plant disease that affects stems, leaves, branches and tubers causing pale green to brown patches form on the leaves. See Appendix 1: Picture 2. CAUSES Fungal

SYMPTOMS •Rotting of the leaves with brown or black spots. •Leaves drop. •Stems become weak. •Wilting of leaves

PREVENTION •Proper spacing •Plant resistant varieties. •Uproot the affected plants •Plant disease free seeds. •Plant at the right time. •Use crop rotation. •Grow in improved or fertile soils. •Early weed.

TREATMENT •Plant tobacco trees at corners of the garden and the middle. •Sprinkle the plants with dry ash. This should be done early in the morning when the dew is still on the plant and/or in the evening. •Spray the garden with filtered ash mixed with 20liters of water, 1 kg of red pepper to 5 liters of human urine (stored for one day).

DISEASE 3: TUBER BACTERIAL BLIGHT

This disease attacks root tuber crops causing them to rot. Also the plant gradually dries and dies. See Appendix 1: Picture 3.

CAUSES Bacteria

SYMPTOMS •Wilt of leaves and stem. •Rotting of tubers and stem

PREVENTION •Plant resistant varieties. •Planting disease free tubers. •Crop rotation. •Improved drainage

TREATMENT •Mix 5 kg of marigold leaves with 10 liters of water, 2 liters of animal urine and ferment for 7-14 days. Sieve and dilute with 10 liters of water. Add 50 gm of washing soap and spray on the leaves once a week until no signs. • Disinfect farm instruments using jik, heating in hot ash or hot water. DISEASE 4: BACTERIAL SOFT ROT (BLACK LEG SOFT ROT)

These infect the tubers, making them inedible. See Appendix 1: Picture 4.

CAUSES Bacteria

SYMPTOMS An infected tuber has cream to coffee brown colored tissues that are very soft and watery. The diseased area often has a black border separating it from a healthy one. The soft rot decay is generally odorless but becomes soiled and slimy when other secondary bacteria invade the infected tissues. Soft rot bacteria can sometimes consume the entire tuber, leaving only its peel in the soil.

The tubers may be infected either in the ground or in storage. Bacteria can rot tubers fully in 3- to 10 days

PREVENTION

There is no known effective control measure of bacterial soft rot. The following practices can lessen its damage to the plant population; •Plant crops in well drained soil. •Hill the plant / raise the ground to encourage excess water to flow away from them. •Do not store stained or cut tubers. •Plant the whole seed tuber. •Control nematodes and other insect pests that serve as vectors (carriers) of the bacteria to invade the plant tissues. •If possible, avoid plant injury during weeding especially when the disease symptoms are observed. •Remove infected plants immediately. •Remove plant residues after harvest. •Practice crop rotation by using crops that are not susceptible to the bacterial soft rot disease like soybean, forage legumes, and small grains.

TREATMENT Wait until the leaves turn yellow and die before digging the potatoes carefully to avoid cutting them. This is because cut potatoes are the most affected.

DISEASE 5: LATE BLIGHT

Late blight is favored by temperatures accompanied by heavy dew or rain. The disease attacks leaves, stems and tubers. The disease consists of small, pale to dark green spots that change into brown or black lesions, depending on the humidity of the air. Under conditions of high humidity and cool temperature, lesions look water soaked and expand rapidly.

It is more damaging during cool, wet conditions. It can affect all plant parts.

CAUSES

Fungal

SYMPTOMS

A newly infected leaf has small, light to dark-green and irregular to circular-shaped water soaked spots. The lesions usually appear first on the lower leaves and continue to grow near the leaf tips or edges where moisture is retained for a longer time. During cool and moist weather, the lesions expand rapidly into large, greasy dark-brown or black spots. As they meet, the entire leaves become blighted and die within a few days. Infection can spread down to the petioles and stems of the plant causing it to wither and die.

An infected potato tuber has irregularly-shaped and slightly-depressed brown to purplish lesions on the skin surface. Underneath the skin, a tan to reddish-brown, dry, and granular rot occurs that extends its infection to the center of the tuber.

PREVENTION •Plant only diseased-free seed and tubers. •Practice proper field sanitation. Properly remove culled potatoes and destroy all volunteer potato plants. •Do not plant potato near tomato or other solanaceous crops field, or vice versa. •Proper plant spacing is important to have proper aeration among the plants and proper sunlight penetration. •Sow tubers in holes more than 15 cm deep to protect tubers from easy infection •Hilling up the plant rows will also reduce tuber infestation. Good soil coverage provides better protection for the potato tubers. •At the beginning of the harvest where late blight is confirmed, harvest potato when the vines are completely dead because the fungi-causing blight will not survive in dead vegetation. •Dry tubers and remove infected ones before storing to reduce additional losses from soft rot diseases. •Keep plants dry

TREATMENT

Destroy and burn any potatoes that have signs of the fungi

DISEASE 6: BROWN ROT OR BACTERIAL WILT

Any fungus or bacterial plant disease characterized by browning and tissue decay.

CAUSES •It spread by infected potatoes •This disease usually develops in areas with poor drainage SYMPTOMS Symptoms include, stunting, wilting and yellowing of the plants. Wilting of leaves and collapse of stems may be severe in young potato stems; dark, small lines are visible. When tubers are cut, grayish white droplets of bacterial cream come out of them.

PREVENTION •This involves mainly the planting of healthy seed in clean soil and the planting of tolerant varieties, in rotation with non-susceptible crops, as well as the application of various sanitation and cultivation practices. Such an integrated disease management approach can lead to significant reduction, or even eradication of bacterial wilt. •Plant disease free tubers •Use crop rotation TREATMENT Disinfect tools used to cut e.g. knives

DISEASE 5: LATE BLIGHT

Late blight is favored by temperatures accompanied by heavy dew or rain. The disease attacks leaves, stems and tubers. The disease consists of small, pale to dark green spots that change into brown or black lesions, depending on the humidity of the air. Under conditions of high humidity and cool temperature, lesions look water soaked and expand rapidly.

It is more damaging during cool, wet conditions. It can affect all plant parts.

CAUSES Fungal

SYMPTOMS

A newly infected leaf has small, light to dark-green and irregular to circular-shaped water soaked spots. The lesions usually appear first on the lower leaves and continue to grow near the leaf tips or edges where moisture is retained for a longer time. During cool and moist weather, the lesions expand rapidly into large, greasy dark-brown or black spots. As they meet, the entire leaves become blighted and die within a few days. Infection can spread down to the petioles and stems of the plant causing it to wither and die.

An infected potato tuber has irregularly-shaped and slightly-depressed brown to purplish lesions on the skin surface. Underneath the skin, a tan to reddish-brown, dry, and granular rot occurs that extends its infection to the center of the tuber.

PREVENTION

•Plant only diseased-free seed and tubers. •Practice proper field sanitation. Properly remove culled potatoes and destroy all volunteer potato plants. •Do not plant potato near tomato or other solanaceous crops field, or vice versa. •Proper plant spacing is important to have proper aeration among the plants and proper sunlight penetration. •Sow tubers in holes more than 15 cm deep to protect tubers from easy infection •Hilling up the plant rows will also reduce tuber infestation. Good soil coverage provides better protection for the potato tubers. •At the beginning of the harvest where late blight is confirmed, harvest potato when the vines are completely dead because the fungi-causing blight will not survive in dead vegetation. •Dry tubers and remove infected ones before storing to reduce additional losses from soft rot diseases. •Keep plants dry TREATMENT Destroy and burn any potatoes that have signs of the fungi

DISEASE 7: POTATO LEAF ROLL VIRUS

CAUSES Aphid transmitted

SYMPTOMS •Leaf rolling (folding) of the upper leaves •Leaves don’t broaden

PREVENTION •Plant potatoes in areas free from aphids •Avoid areas with high rate of virus infection i.e. incase of infected areas, leaves show on every germination •Timely planting to avoid infection by aphids •Plant resistant varieties

TREATMENT

Remove infected plants Control aphids by early weeding and use of organic sprays. Get 50gm of neem tree leaves + 3 cloves of garlic, crush them and add 5 litres of water. Ferment for 2 days (48 hours). Dilute with 2 and a half litres, add 1 tea spoon of powdered soap, sieve and spray on the plant at 7 days interval.

COMMON PESTS: PREVENTION & MANAGEMENT

PEST 1: ROOT KNOT NEMATODES These are microscopic worms that live in the soil and feed on plant roots. Infested tubers are unattractive, but edible when peeled.

SYMPTOMS •Damaged and stunted of crops. •Poor growth of plants and poor color of foliage. •The damaged roots cannot supply sufficient water and nutrients to the aboveground plant parts, and the plant is stunted and eventually dies. •Small root swellings to develop on the tubers.

PREVENTION & CONTROL •Once the garden is affected, transfer to a nematode free area. •Use varieties that are resistant to root knot nematode. •Establish a rotation system with certain varieties of plants like tangerine and lemon which reduce root knot nematode populations in soils. •Reduction occurs by starving the nematode. Keep these plants free of weeds and grass to prevent nematodes from feeding on roots. •Destroy roots immediately after harvesting

TREATMENT •Tilling the soil, moistening, and then covering with clear plastic for six to eight weeks •Continuous tilling helps nematodes to be brought to the surface so as they die due to the effect of the sun •Spray the crops with a mixture of 2litres of urine, 2handfuls of marigold, ½ a cup of red chilies, 1handful of tobacco, 1 piece of brown or white bar soap, 1/2kg of ash. PEST 2: MOTHS

Moths are usually white flying insects, whose larvae feed on plant leaves. Black moths are small insects with white markings on the wings and body that attack crops while in the storage. SYMPTOMS .Proper ventilation and hygiene in the store. .Use of proper spacing. .Timely weeding

PREVENTION & CONTROL

•Plant pest free crops to avoid spread •Weed around the garden TREATMENT

Use 3-5 kg of pounded neem seeds without covers, add 10 litres of water and store for 3 days. Dilute 1 litre with 9 litres of water. Add 100 ml of soap then stir and spray. Once a week until no signs are seen.


PEST 3: LEAF MINERS Leaf miners are usually the larvae of flies, moths, or beetles that feed or “mine” between the upper and lower epidermal leaf surfaces. The larvae tunnel through the leaf creating a narrow, whitish colored serpentine (winding) mine (Figure 1) or blotch (blister) (Figure 2) type mine. The tunnel is clear, except for the trail of black fecal material left behind as larvae feed.

SYMPTOMS •Spotted, damaged leaves and stems. •Poor quality damaged fruits •Plant stunting

PREVENTION & CONTROL •Remove weeds regularly. •Plant disease resistant varieties. TREATMENT •Prepare 1 kg of neem leaves dipped into 2 liters of water and left overnight. Boil for 15-20 minutes until 1/4 is left. Dilute with 10-15ml of water. Use the solution to spray. •Get 1 kg of dry red pepper, pound it and mix with 5 liters of cold water. Sprinkle on the affected plants.

PEST 4: WIRE WORMS Wireworms are very thin, yellow, pink or orangish worms that feed on potatoes. Wireworms also feed on other plants in the vegetable garden such as lettuce, beans, peas, beets and carrot plants. Although wireworms can damage large portions of individual potatoes, the undamaged portions of the vegetable are still edible even though you may find them unappetizing after removing the wireworms. Damage from wireworm infestation appears in the form of potato plants' growth being stunted or incredibly slowed as compared to normal growth patterns of potato plants.

The potato itself may look as if it has had several dark brownish to black holes punched into it. These are the sites in the tubers which the wireworms have tunneled in and out of to feed. If you have a wireworm infestation in your potato plants or your vegetable garden you will find clusters of wireworms both in the tubers and in the surrounding soil but rarely will you see wireworms above ground because they only feed on underground portions of the potato plants. http://www.essortment.com/all/potatoesdisease_rdja.htm SYMPTOMS •Damaged tubers •Rotting of the tubers •Poor quality tubers. •Damaged leaves and the stem.

PREVENTION & CONTROL •Use well drained land. •plant on ridges •Proper storage on well created platform. •Plant on ridges.

Treatment Sprinkle ash mixed with cow dung on the crops TIPS FOR PEST & DISEASE CONTROL •Plant undamaged tubers. •Avoid planting where legumes have been previously harvested. •Early plant to prevent disease attacks. •Weed on time. •Clear bushes around the garden to prevent pest attacks. •Plant at the right spacing. •Plant tubers from healthy looking disease free plants

HARVESTING

Harvesting of the Irish Potato is done after 75 to 140 days from planting to maturity. The period however depends on the variety.

Irish Potatoes are generally mature when the plant starts to turn yellow. Immature potatoes will often skin and bruise easily. When digging potatoes, if the skin is not set and is easily removed, delay the harvest. Avoid harvesting the potatoes when the soil is wet to avoid potato diseases.

To harvest irish potatoes, cut off stems 2 weeks before harvesting to harden the tubers. Dig them out with a forked hoe.

Tips: •Avoid harvesting when the soil is wet to prevent fungal diseases. •Avoid cutting the stem tubers by scooping at a distance of 1.5 ft from the plant. •Make heaps at different distance for easy collection and avoiding unnecessary losses.

POST HARVEST

•Use baskets, boxes and basins for transportation of Irish potato tubers. •Remove the harvested tubers carefully from the bags or sacks and sort to remove damaged ones. •Store in an appropriate facility, with the following features. •Well ventilated wooden store. •Roof (water proof) •Raised platform(crib) •Provide enough aeration and light.(air in =air out) •Door for security and other pests. •Use rat guards on stands.

Storage/home use: Constantly (periodically) check the tubers and remove the damaged, rotten /spoilt ones.

Tubers for seeds: Disinfect with lantana camara, neem, ash, marigold, tephrosia and eucalyptus tree leaves to repel pests and store on top of dry grass. Prepare for the next planting.

For sale: Select the damaged ones from good ones before taking to the market for sell.

For consumption.

•Direct cooking: sort dormant ones, peel, wash, prepare as desire and serve when hot or cold. •Chips: wash, peel, slice, deep into boiling cooking until soft and serve with salads when still hot. •Crisps: peel, wash, slice sun dry and fry. •Vegetable: peel, wash and boil together with other soup e.g. meat or chicken and serve while still hot.

Common Diseases

Below is a list of different techniques for prevention and management of diseases that commonly affect this crop. If you want to add a technique, open the editor and edit the "Diseases" section.

Common Pests

Below is a list of different techniques for prevention and management of pests that commonly affect this crop. If you want to add a technique, open the editor and edit the "Pests" section.


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