Potato production

Potato is grown in more than 100 countries, under temperate, subtropical and tropical conditions. It is essentially a “cool weather crop”, with temperature being the main limiting factor on production: tuber growth is sharply inhibited in temperatures below 10°C (50°F) and above 30°C (86°F), while optimum yields are obtained where mean daily temperatures are in the 18 to 20°C (64 to 68°F) range.

For that reason, potato is planted in early spring in temperate zones and late winter in warmer regions, and grown during the coolest months of the year in hot tropical climates. In some sub-tropical highlands, mild temperatures and high solar radiation allow farmers to grow potatoes throughout the year, and harvest tubers within 90 days of planting (in temperate climates, such in northern Europe, it can take up to 150 days).

The potato is a very accommodating and adaptable plant, and will produce well without ideal soil and growing conditions. However, it is also subject to number of pests and diseases. To prevent the build-up of pathogens in the soil, farmers avoid growing potato on the same land from year to year. Instead, they grow potato in rotations of three or more years, alternating with other, dissimilar crops, such as maize, beans and alfalfa. Crops susceptible to the same pathogens as potato (e.g. tomato) are avoided in order to break potato pests’ development cycle.

With good agricultural practices, including irrigation when necessary, a hectare of potato in the temperate climates of northern Europe and North America can yield more than 40 tonnes of fresh tubers within four months of planting. In most developing countries, however, average yields are much lower – ranging from as little as five tonnes to 25 tonnes – owing to lack of high quality seed and improved cultivars, lower rates of fertilizer use and irrigation, and pest and disease problems.

Soil and land preparation

The potato can be grown almost on any type of soil, except saline and alkaline soils. Naturally loose soils, which offer the least resistance to enlargement of the tubers, are preferred, and loamy and sandy loam soils that are rich in organic matter, with good drainage and aeration, are the most suitable. Soil with a pH range of 5.2-6.4 is considered ideal.

Growing potatoes involves extensive ground preparation. The soil needs to be harrowed until completely free of weed roots. In most cases, three ploughings, along with frequent harrowing and rolling, are needed before the soil reaches a suitable condition: soft, well-drained and well-aerated. http://www.fao.org/potato-2008/en/potato/cultivation.html

Climate and soils

Potato basically requires relatively mild temperature during early growth and cool weather during tuber development.

It does well under well-distributed rains or moist weather situations to high temperature, humidity rains are not conducive to potatoes as these lead to insect-pest, disease, viruses epidemics.

Impeded drainage or lack of aeration also is considered harmful as it restricts the tuber development.

Therefore, climatic conditions are very crucial for determining the potato yield.

Its general and specific climatic requirements are delineated as under.

General climatic requirements

Potato is a temperate or cool season crop which needs a low temperature, lower humidity, less windy and bright sunny days. It thrives best in cool regions where there is sufficient moisture and fertile soil.

Potato needs about 25°C at the time of germination, about 20°C for vegetative growth but between 17-20°C for tuberization and tuber development. It is noticed that higher temperature has an adverse effect on the tuber growth, whereas temperature above 30°C stops tuber formation completely.

It is probably because at higher temperature the rate of respiration increases and the carbohydrate formed by the process of photosynthesis is consumed rather than stored in the tubers. Under higher temperature the plants are elongated leaves become wrinkled and plants have silky appearance. Tubers do not develop under such situations.

Cloud days, rains and high humidity are very congenial for spread of fungal, viral and bacterial diseases, and such conditions are not good for the crop.

 

 

Specific Climatic Requirements of Potato

Potato is a crop of temperate climates and its importance is great both for human consumption and for industrial uses. There are different varieties of potatoes which are classified on the basis of the length of the vegetative period. There are early varieties with 90 days vegetative period; others are medium verities with 90-120 days of vegetative period and still others are late varieties with over 120 days of vegetative periods.

 

Temperature

Potatoes are planted when the soil temperature at a depth of 4 inches is 8 ° to 10 °C. When they are planted at a higher temperature, the tubers are damaged, but when they are planted at a lower temperature, the sprouting is retarded. It has been estimated that a mean daily air temperature of 10 ° C, the length of the period from sowing to sprouting is 27 days. But when the mean daily air temperature is 22 ° C, sprout appears after 12 days.

Experiments have shown that a most favourable temperature for the potato tubes is 18 ° to 20 ° C. At 22 ° to 25 ° C the formation of the tuber is retarded and beyond 29 ° C it completely stops. Mild frost to the extent of -1° C partially damages the potato leaves, but when the temperature falls below -2° C, the exposed parts of the most of the varieties are destroyed.

 

Moisture

The water requirements of the potato crop during its vegetative period are not very high. It has been estimated that rainfall of 15 to 20 cms or an equivalent amount of irrigation is sufficient for the normal crop. At the time of germination, the crop requires little external moisture, because the potato tubers themselves contain adequate amount of water. However, as the leaves grow after sprouting, the water requirements of the crop increase.

The optimum soil moisture for the potato crop is 65 to 80 percent at the field capacity. Just after sowing and before sprouting, heavy rains adversely affect the crop. Alternate dry and rainy weather leads to an excessive growth of potato plant and encourages the formation of the off-shoots in the young tubers. Potato requires a high light intensity if the crop remains in shade or if it is too densely planted, the yield is adversely affected. http:www.ikisan.in/ap-potato-climateandsoils.html

Variety

Click here to view potatoes https://en.wikipedia.org/wiki/List_of_potato_cultivars

Seed Rate:

Potatoes are propagated by tubers, planted either whole or cut into pieces. To obtain maximum yields, healthy, disease-free tubers, free from mixture of other varieties, should he use. Seed rate depends on tuber size; 800-1000 kg/ha is generally recommended. Choudhary et al (1990) conducted a trial comparing improved seed of the Swat and Kaghan varieties brought from the Kaiam Integrated Development Project with seed from the local market. Potatoes grown from the improved seed gave better soil coverage, had a lower incidence of virus attack and higher tuber weight and gave higher yields than those from the locally purchased unimproved seed.

Irrigation:

Potatoes need frequent irrigation. The first irrigation should be given immediately after sowing, and thereafter at one week intervals. After tuber formation, the frequency of irrigation is decreased. Care must be taken while irrigating that the water does not reach fee top of the ridge.
Irrigation should be stopped a few days before harvesting.

Manures and Fertilizers:

Potato has a high nutrient requirement; a yield of 25 tons of tubers/ha depletes the soil of 119 kg of N, 50 kg of P and 225 kg of K. In light soils and places where organic manures are not easily available, green manuring is beneficial. Well-rotted FYM at 30 t/ha should be incorporated into the soil three to four weeks before planting. Research on fertilizer requirements conducted in the Punjab and Sindh suggests that 100 kg N, 80-100 kg of P2O5, and 50 kg K2O per hectare are sufficient- to obtain good yields.

http://agriinfo.in/default.aspx?page=topic&superid=2&topicid=942

 

Harvesting

For most commercial varieties, yellowing of the potato plant’s leaves and easy separation of tubers from stolons indicate that the potato crop has reached maturity. If the potatoes are to be stored rather than consumed immediately, they are left in the soil to allow their skin to harden – hard skin also help seed potatoes to resist storage diseases. However, leaving tubers for too long in the ground increases their exposure to the fungal disease black scurf and increases the risk of losing quality and marketable yield. To facilitate harvesting and stop tuber growth, potato vines should be removed two weeks before the potatoes are dug up. Depending on the scale of the production, potatoes are harvested using a spading fork, a plough or commercial potato harvesters that unearth the plant and shake or blow the soil from the tubers. During harvesting, especially if it is done mechanically, it is important to avoid bruising or other injuries, which provide entry points for storage diseases and reduce the commercial, processing quality and storability of the tubers. In suitable environments and where growing conditions are adequate, commercial yields are in the range of 40–60 tonnes per hectare. In many developing countries, however, they are far below this figure, with national averages of about 10- 20 tonnes per hectare. http://www.fao.org/3/a-i1127e.pdf

 

Planting

Stages in crop development

1. Planted seed tuber
   2. Vegetative growth
   3. Tuber initiation
   4. Tuber bulking

 

1                      2                                  3                                              4

 

Potato tuber moth: Phthorimaea operculella

Marks of identification:

Potato Moths are small narrow winged greyish brown in colour, measure about 12 mm long. Full grown caterpillars are pinkish white or pale greenish in colour and 14-20 mm long.

Nature of damage by potato tuber moth

• It bores into petioles and terminal shoots
• The main danger is to tubers both in the field and under storage.
• The caterpillars bore the tubers and feed on the pupal as a result of damage the potato tubers rot.
• The presence of black excreta near the eye buds helps to detect its presence in the tubers.

Larvae                                                                        Leaf damage

 

                                                             Tuber damage

Management of potato tuber moth:

In field: –

Timely earthling up of the crop to cover the exposed tubers helps in reducing the intensity of infestation.

Two sprays with 0.05% quinalphos or 0.1% carbaryl at 15 days interval starting 60 days after planting controls the pest effectively.

Heaps of harvested potatoes should not be kept exposed in the field but covered with straw and infested tubers should be rejected before storage.

Release Copidosoma koehleri 50 000 adults/ha/release, Chelonius blackbernii 15000 adults/ha/release an egg-larval parasite to reduce 50-55% infestation.

However, if harvest should be delayed and leaves have senesced, apply on the soil surface any one of the following:  Lambda cyhalothrin 600 ml/ha or Indoxacarb 30 WG 130 g/ha or Runner (methoxyfenozide) 240 SC 600 ml /ha

In storage

• The potatoes should be stored in well-ventilated cool and dry places with temperature not exceeding 21⁰ Fumigate the tubers with CS₂at the rate of 1kg/27 cu.m for 48 hours at 70⁰F or ethyl bromide at the rate of 1 kg/27 cu.m for the least three hours before storage.
• Covering of tubers with 1″ layer of dry sand is stated to be a cheap and highly effective remedy against the pest
• Walls of godown should be sprayed with 1% Malathion at an interval of 3 months.
• Treatment of seed potato tubers with 5% Malathion at the rate of 125 gm/100kg is also reported to offer good protection against the pest. Such treated potatoes, however, should not be used for consumption.
• If cold storage facilities are available, the produce can be safely stored for a longer period.

 

Potato Cut worm: Agrotis ypsilon

Marks of Identification:

Potato cutworm Moth is medium sized (22-26 mm longer), stout with greyish brown wavy lines and sports on fore wings and creamy white wings. The moths are active at dusk and are attracted by light. Full grown caterpillars are 40-48 mm long dirty black in colour and have habit of coiling at slightest touch.

Nature of damage

It damage plants and tubers, especially after dark

They attack young plants by severing their stems, pulling all parts of the plant into the ground and devouring them particularly at 25 – 35 days after planting (DAP)

Signs of damage on tubers are boreholes, larger than those made by potato tuber moths

 

Damage during seedling stage                                              Larvae with symptom of damage 

 

 

Management of Potato cutworm

• Heaps of green grasses may be kept at suitable interval in infested field during evening and next day early in the morning along with caterpillars to destroy
• Clean cultivation and mechanical destruction of caterpillars also help in reducing pest infestation
• Irrigation also brings them on the surface and birds shall predate them
• 5% Carbaryl poisonbait at the rate of 25-60 kg/ha controls the pest effectively
• Soil application of chlordane or Heptachlor dust at the rate of 50 kg/ha found effective against the pest.
• Apply any one of the followings insecticides Coragen 20 SC 300 ml /haor Tracer 48 SC 200 ml/ha or Indoxacarb 30 WG 130 g/ha

 

Epilachna beetle of Potato: Epilachna viginatioctopunctata

Marks of identification:

The epilachna beetles of potato are special in shape, pale brown in colour and motted with black spots. The grubs are yellow with hairs on their body

 

Nature of damage by epilachna beetles

Both grub and beetle eat the chlorophyll of the leaf in between the veins and cause characteristic skeletonised patches on leaves

Epilachna beetle in Potato

 

Management of epilachna beetles

• Hand packing of grubs and collection of beetles by hand nets during early stages of attack, helps in reducing the intensity of infestation
• Conservation and augmentation of natural parasitoids viz. Pediobius foveolatus, Pleunotrogrus faveolatus and Tetrastichus sp
• Application of Neem, Mahua, ground nut cakes are efficient in suppressing the pest population
• Spray ofMalathion 50 EC in 200 liters of water per acre provides up to 82 percent kill of this pest.

 

 

 

 

Aphids in potato: Myzus persicae

Marks of Identification:

Aphids are tiny yellowish soft-bodied insects, the adult is along 1mm long and has two projections called cornicles on the dorsal side of abdomen

Nature of damage by Aphids

Direct damage:

• It puncturing them and sucking their juices.
• They damage the young and soft parts of plants, such as new leaves and shoots.
• Signs of damage are leaves not opening properly and being smaller in size.
• Severe infestation can cause shoots to wilt and dry out.

Indirect damage:

Aphids have wings and can move from plant to plant spreading viral diseases (potato virus Y and potato leaf roll virus), picked up from infected plants

Aphids secrete a sugary liquid that stimulates black sooty mold growth. It can cover the surface of leaves which affects the way they absorb sunlight

 

 

Management of Aphids in Potato

• Apply any one of the following insecticides Actara (thiamethoxam) 25 WG 600 g/hain the furrows at planting or spray Confidor (imidacloprid) 70 WG 125 g/ha or Actara 25 WG 80 g/ha after 6 weeks
• In case of seed crop, apply 5 kg of Thimet 10G (phorate)to the soil at the time of the first earthing up
• Encourage the activity of Dieretella spp, Ahelinus and Ahidius parasitoids and ladybird beetles and syrphid predators

 

Jassids of Potato: Empoasca fabae:

Marks of Identification:

The adults are greenish yellow with front wings having a black spot on each, at the apical margin and two black spots on the vertex of the head. The nymphs are also green. They walk diagonally.

Nature of damage by Jassids in potato crop

Both nymphs and adult suck the sap from the lower surface of the leaves

The damaged leaves curl upwards along the margins and turn yellowish and show burnt patches. This affect adversely plants growth and yield

 

Hopper burn symptoms – burnt patches

 

Management of Jassids in potato

• Seed treatment withimidacloprid (Gaucho) or Cruiser @ 5 grams per kg In the field, spray with imidacloprid @ 1 ml in 3-4 liters of water or fipronil @ 2 ml per liter.
• Spray the crop with 300 ml of Rogor 30EC (dimethoate)or metasystox 25EC (methyl-demeton) or 75 ml of dimecran 85SL ( phosphomidon) in 80-100 liters of water per acre. If necessary, repeat the spray after 10 days.

 

Thrips of potato: Helicothrips indicus:

Marks of Identification:

The adults are minute, delicate insects, less than 1 mm long and are light yellow in colour. Wings have fringe or hairs throughout and hence they are called fringed, winged insects. The nymphs are still smaller, minute and wingless.

Nature of damage by thrips in potato

Direct damage

• It damages the undersides of leaves by scrape the epidermis and such the oozing sap
• They damage young and soft parts of plants such as new leaves and shoots
• As a result, leaves curl downwards and change to a blackish- silver colour
• Severe infestation causes young leaves to wilt and dry out

Indirect damage

It can carry and spread spotted wilt virus diseases

 

 

Spotted wilt virus                                                             Thrips underside of leaves

 

Management of Thrips of potato

Spraying with Tracer (spinosad) 48 SC 300 ml/ha or 0.02% phosphamidon, 0.03% dimethoate, methyl demeton or thiometon control the pest effectively.

In the field, spray with imidacloprid @ 1 ml in 3-4 liters of water or fipronil @ 2 ml per liter.

Sufficient watering – Thrips thrive in dry conditions and watering will increase moisture and inhibit their development.

Using black silver mulch – Light reflected from the silvery surface illuminating the undersides of leaves can repel thrips.

 

White grub of potato:

Marks of Identification:

White grubs are the larval form of beetles. They are large reaching 2-3 cm in length, are shaped like the letter C, and have three pairs of legs on their thorax. Their heads are hard and ruddy-brown in color, and they have strong mandibles.

Nature of damage by White grub of potato

Tubers damaged by irregular holes. More than two holes are often found in one tuber.

These holes are not so deep, as white grubs do not enter and live inside tubers.

Severe infestations usually occur in fields previously covered with grasses.

Management of white grub of potato

• Collecting larvae when tilling soil, planting, weeding and hilling up.
• Avoiding using un composted organic fertilizer, as it is a suitable breeding ground for this pest.
• Avoiding to plant potatoes in fields that were previously covered with grasses.
• Flooding field prior to planting, where possible farmers can consider temporarily flooding fields, particularly on severely infested fields.
• Making use of bird predators to reduce white grub populations.

http://www.krishisewa.com/articles/disease-management/137-potato-insect-pests.html

Yield potential
In subtropical areas, you can plant in April/May. Usually the yield isn’t wonderful but can fill a need – especially in remote areas. Temperatures above 30°C can reduce yield. Cool seasons on the Highveld certainly make a big difference in yield potential. The effect of high temperatures can be partially negated by frequent, light irrigation. Since high temperatures on the Highveld are related to dry periods, if the irrigation method enables you to irrigate frequently it will make a big difference.

Yield potential is affected by many other variables, such as soil and air temperature, soil fertility, day-length and sun intensity. You can experiment with planting dates and varieties to maximise your yield, but this will also have to fit into the most profitable harvest date. It doesn’t help if you get a higher yield only to get a lower price if the higher yield doesn’t make up for the lower price. All these factors need to be taken into consideration so as to get the variety and planting date to work best for you. https://www.farmersweekly.co.za/crops/vegetables/climate-soil-and-potatoes/