Manual for Potato Clean Seed Production

7/30/2019 Manual for Potato Clean Seed Production

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MANUAL FOR POTATO CLEAN SEED PRODUCTION

Good quality seed tuber is perquisite for higher potato production. Seed alone

accounts for 50% of the total cost of potato cultivation. The combined use ofquality seed and improved agronomic practices can therefore increase existing yield

levels enormously.

Good quality seed can be produced in areas-

i) the soils are free from common scab, black scruf and brown rot (bacterial

wilt) and nematodes.ii) a period of at least 80-90 days in plains and 120days in highlands of aphid

free or aphid population below thresh hold level environment is available

for crop to grow.

Field practices

* Land selection: Well irrigated medium land with sandy loam soil type are best suited

for seed production. Seed of one variety should be multiplied in one field. A gap of 5mor 15feet should be maintained around the seed plot. Other crop may be planted in the

gap

* Land preparation: Land should be leveled and prepared in early November where

the seed crop is to be planted. It is imperative that field should be ploughed duringsummer months, and soil be kept open for some time to reduce incidence of soil bornediseases and also control perennial weeds. During first ploughing apply FYM @

3500kg/ha. Apply granular insecticide in the field and mix with the soil.

*Fertilizer application: Follow fertilizer dose 250kg N, 150kg P205 and 150kg K20.

Apply N full P and 3/4th Potash as basal dose. Add another N and 25% of the

during the earthing up. Fertilizer should apply in furrows not by broadcasting.

* Seed source: Seed source may be tissue cultured derived minitubers/ breeder

seed/foundation seed free from diseases.

* Seed size and seed rate : 20-30g seed tuber with multiple sprouts should be used asplanting material. Optimum seed rate should be 2.0t/ha. to get a good crop.

*Planting time: Night temperature around 22oC is the optimum period for Potato

planting. Early November to Mid-November is suitable period for West Bengal.


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*Planting of Potato: Take out seed tuber from cold storage 10-12 days before planting.

Spread the tuber in shade to get uniform germination. Separate out rotten and blunt-eye

potato. Plant potato with two-three viable eyes. The distance between two rows shouldbe kept 20 cm and plant to plant 15 cm. Adequate soil should be added to ridge to cover

the seed tuber.

*Irrigation: Sprinkled (Jhapta) water every 3-4 days interval from sowing to first

earthing up. Apply flood irrigation in furrows at 7-8 days interval. Take care so waterdo not cross half of the ridge. The frequency of watering may differ depending on soil

moisture status. Potato plant should not be suffered from any moisture stress during crop

growth. Watering should be stopped before 10 days of harvest.

* Intercultural Operations: Weeds are a serious problem in potato crop planted with

out pre-sowing irrigation. Pre-sowing irrigation not only useful for uniform germination

of the crop, but also helps to control the weeds to a large extent. A majority of weedspecies starts germinating in the field with pre-sowing irrigation and is latter killed

automatically by when field is ploughed to prepare for planting.

When the potato plant is 20-25 days old, the ridges and furrows are opened manually or

with a plough, and the remaining half of the Nitrogen in the form of urea is applied inthe furrows. The ridges are thereafter earthed up. Delay in earthing up may damage

stolons, eventually resulting in yield reduction.

* Monitoring and Roughing : Regular monitoring diseases, insect and off types areessential for quality seed production. At least three inspections are needed to remove off

types and diseased plants showing symptoms of mottling, mosaics and leaf-roll.

a) the first roughing has to be done after emergence and before earthling up.

b) the second roughing should be preformed after 40-45 days after sowing and

c) the third roughing are to be performed just before dehaulming the crop .

While removing the diseased plants, proper precautions should be taken to avoid thepossible transmission of diseases to healthy plants.

* Plant protection: Application of granular systemic insecticide, Furadon 5G or

Phorate 10G @ 10kg/ha at the time of planting is extremely useful to control Jassids,

White flies and leaf hoppers checking the spread of victor transmitted viruses.Insecticides remain effective for 40-45 days from day of application.

Two to three sprays of Demicron/ Nuvacron/Metasystox@ 1.0 litre/ha should be applied

at intervals of 10-12 day depending on appearance and population density of aphids.


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For Potato late blight (LB) one prophylactic spray of Diathane M-45 @ 2kg/ha

(Mancozeb @ 0.2%) should be done on both susceptible and resistant varieties.

Dithane M-45 should be repeated at an interval of 8-12days depending upon weatherconditions.

In case the spread of leaf blight is not checked by Diathane M-45, Ridomil (metalaxy)

@ 4kg/ha is sprayed on the crop at an interval of 10-15days.

* Dehaulming: The seed crop should be dehaulmed before the aphid population crossesthe critical level (20 aphids/100 compound leaves). Haulms may be pulled by hand or cut

with a sickle as close to the ground as possible. Vines should be kept on the ridges top

protect potatoes from high temperature and direct sun light. Re-growth of stems should

be checked in order to control vector transmitted viruses.

* Harvesting: Harvesting of a crop is recommended after 10-12days of dehaulming

when tuber skin is hard enough to bear handling operations. The crop may be harvested

manually with a spade or a bullock driven plough/digger or tractor. At harvest time, thesoil moisture in the field should be optimum to avoid damage to tubers.

The harvested potato should be kept in heaps for 5-7 days for skin curing., avoidbruising of tubers during harvesting and transporting from the field.

* Grading: After curing in heaps, the seed tubers are graded to get better returns in the

market. Seed potatoes are graded in four grades viz.

a. Small size below 25g (50mm)

* Seed treatment: To control surface borne diseases like common scab and black scruf

(Rhizoctonia), the graded tubers may be cleaned with water and should be sprayed with5% solution of boric acid. The treated tubers should be dried in the shade . Pack it in

leno bags. Seed should reach cold stores timely or else the rising ambient temperature

may adversely affect tubers.

Important diseases associated with seed production.

Bacterial wilt ( Ralstonia Solanacearum) : This is a bacterial disease. The bacteria enterthe plant through roots. Inside plant they multiply and eventually kill the plant. Plants

that are not heavily infected can still produce tubers. These tubers contain the

bacteria and carry the disease to the next season. The bacteria also survive in the

soil.

Symptom: Plants infected with bacterial wilt can easily be identified in the field. As a

result of bacteria multiplying in the vascular system of the plant the flow of water from


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the roots to the above ground plant becomes blocked. The sprouts wilts due to a lack of

moisture. This occurs despite the fact that there is no water stress visible in other

plants, and the soil is actually moist. If plants are infected in the later stages ofdevelopment, when tubers are developing, the bacteria will get into the tubers and

survive there. This will give following wilt symptom in the tuber.

1. Oozing eyes

2. Soil sticking to the eyes

3. Vascular brown ring and Ooze come out from the vascular ring.

4. Rotting of Tuber.

Symptomless infection: (Latent infection) :

Tubers infected with low number of bacteria, not showing any disease symptoms will

look like absolutely healthy. But once it is planted, the plant will develop wilt and die.

Control :

1.Strict roughing When a first symptom of disease appear a plant has to be removed

with its all tubers and some soil from the plant hole. Put some ash and lime in the

hole. Remove infected plant and soil and burn it.

2.Crop rotation:- Through crop rotation the bacteria causing the disease will have

nothing to survive on and will die due to lack of food. During rotation period no crops

like tomato, tobacco, Brinjal, capsicum or other Solanaceous crops can be grown.

3. Avoid run-off from infected fields.

4.Wash tools and shoes with water or bleaching powdwer.

Viruses : Seed generation caused by viruses is much less visible than bacterial wilt, butmuch more widespread. Once a potato plant becomes infected with a virus , there is no

cure. All its tuber carry virus. Virus do not kill the plants, but make the plants sick. Over

the seasons the symptoms worsen as more and more infected. This quickly results inpoor yields.

Controll:

Potato viruses transmitted by Aphids who feed on the sap from the potato plants. Also

some other sucking insects like white flies and Thrips can transmit viruses as well as

nematode and mites.


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1. Vector control :Sprays:

Application of granular systemic insecticides, Furadon 5G or Phorate 10G 2 10kg/ha at

the time of planting is extremely useful to control Jassids, whiteflies , and leafhoppers.Two-three spray of Demicron /Nuvacron /Metasystoc @ 1.0litre/ha should be given 10-

12 days intervals depending on appearance of Aphids.

Dehaulmning : The seed crop should be dehaulmed before the aphid population crooses

the critical level (20 aphids/100 compound leaves)

Use of healthy seed : Regular renewal of healthy seed potatoes reduce virus effect

Roughing : Remove plants with virus symptoms.

Minimize mechanical damage: Avoid tuber damage.

Fugus:

Late Blight- disease on potatoes is caused by fungus (Phytophthora infestans). If lateblight is controlled a whole potato crop can be lost. Late blight is rarely affecting tubers.

Plants with some late blight symptoms can safely be selected as mother plants for

seed.

Symptom: The symptoms of late blight are irregularly to round shaped lesion . They

may be surrounded by a small band of still green or yellow tissue, that is clearly

infected. Lesions are usually not delimited by the vein . Late blight can also causelesions on the stems of the plant.

Late blight is transmitted in the form of spores which are formed on the edge of the

lesions. They are transmitted over large distances by wind . From one spore landing in apotato field the whole fields can become infected quickly if the weather is right. Late

blight growth is fastest under humid and cool (5-20oC) conditions.

Control:

1. Varietal resistance : use tolerant potato variety like Kufri Jyoti.

2. Fungicides a.) Contact fungicide like Mancozeb (Dithane M-45) brand name ismost commonly known. It protect the leaves against the entry of the fungus into the

plant. b) sustemic fungicides like Metalaxyl protect the plant from inside.

Manual for Potato Clean Seed Production

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