Common Physiological Disorder, Pests and Diseases of Potato.

Common Physiological Disorder, Pests and Diseases of Potato.

Black or hollow heart of potato.
In this disorder, central tissues of the affected tubers show dark grey or black discoloration due to sub-oxidation (black heart). In advanced stages of the disorder, the affected tissues dry and separate to form cavities brought about very rapid growth of tubers.  The symptoms are internal, therefore, it can be seen only after cutting the tuber. It is more common in large-sized tubers.


Cause of Black or hollow heart of potato.
1. High soil temperature (Above 33-degree Celsius ) during growth and maturity of tubers.

2. Rapid growth and development of tubers followed by sudden irrigation.

3. Unfavorable supply of oxygen during storage and transport.

4. Storage of tubers at high temperature. Even 3 -4 degree Celsius temperature is not safe to store the potato.

Control for  Black or hollow heart of potato.
1. Follow close spacing, remove the foliage and avoid over-fertilization.

2. Irrigation of the crop frequently to maintain soil temperature below 33 degrees Celsius.

3. Provide proper ventilation in storage and during transportation.

Black or hollow heart of potato.

Greening of potato.
The tubers turn green colors when exposed to direct sunlight. The green pigment produced is Solanin which is slightly poisonous and makes the tubers unfit for consumption.

Control for Greening in potatoes.
Earthing up should be done to avoid the exposure of tubers to direct sunlight.

Potato Sprouting problem in Storage.
Sprouting of potato tubers in storage is the major problem of storage which deteriorates the quality and makes the product unfit for consumption. The intensity of sprouting depends on the variety, maturity, storage temperature and relative humidity.

Control for Potato Sprouting problem in Storage.
1. Grow those varieties that sprout late.

2. Spray the crop with maleic hydrazide @3000 ppm at 15 days before harvesting.

3. Store the potato tubers in cold storage 2-4 degree celsius and 90-95 percent relative humidity.

Poor / Uneven Potato Sprouting in the field.
It is the practical problem being faced by farmers. The following factors are responsible for poor /uneven sprouting of seed tubers in the field.

1. If seed tubers are planted just after the removal from cold storage as they have dormancy.

2. Select unsprouted seed tubers for planting.

3. Deficiency of moisture in the field at planting and sprouting.

4. Cutting of tubers in small pieces leads to loss of apical dominance which results in poor/uneven sprouting.

5. Several micro-organisms like Fusarium and Rhizoctonia (fungi), Pseudomonas and Corynebacterium  (bacteria) attack the planted seed tubers and decay them.

Control for Poor / Uneven Potato Sprouting in the field.
1. Use the tubers for planting after breaking the dormancy.

2. Keep the tubers at room temperature for 15 days in 30cm thick layers to induce sprouting and select those tubers having thick, green and multiple sprouts.

3. Cut the seed tubers in pieces just before planting and dip them in Agallol-6 or Aretan @ 0.3 percent for two minutes.

4. Avoid over- flooding and maintain proper soil moisture in the fields at planting and sprouting.

Poor / Uneven Potato Sprouting in the field.

Potato Dormancy Problem  -
Potato tubers have dormancy which does not sprout when planted soon after harvesting. Therefore, the dormancy causes delay and erratic crop stand in the field. It becomes a serious problem particularly when two crops are to be taken in rotation and tubers produced in hills are used to raise the crop in the plains of India just after harvesting.

How to control Potato Dormancy .
1. The cutting of tubers in pieces during the advanced stage of dormancy may help in avoiding/breaking the dormancy.

2. Cut the freshly harvested tubers in pieces having at least two healthy eyes and dip them immediately in 1%  solution Thiourea for one hour. The planting should be done just after treatment or keep in wet gunny bags for one night.

3. When the hill potatoes are to be used as seed, they should be dipped in a 1 ppm solution of gibberellic acid for one hour. Dry them in shade and fill in small gunny bags and keep them for 10-12 days in dark and ventilated space to induce sprouting.

Serious Insects in Potato field.

Aphid in the potato field.
The nymph and adults suck the sap from tender parts of plants. The infected plants remain stunted, leaves curled and plant vigor is reduced. They excrete honeydew on which black sooty mold develops which checks the photosynthesis. They also act as a vector for several viral diseases like potato mosaic, leaf roll virus, etc.

Aphid Control in potato field-

1. Incorporate  Phorate 10G @ 15 kg/ha in the soil at planning in the furrows.

2. Spray the crop with Imidacloprid 17.8 SL @0.5 - 0.6 ml/liter water.

Aphid in the potato field

Jassid in the potato field.

The tiny insects suck the sap from foliage and result in yellowing curling of leaves and finally cause hopper burn to the plants. They transmit several mycoplasma diseases. A. dravidans transmits the purple top roll and Witche's Broom.

Jassid Control in potato field.
1. Incorporate  Phorate 10G @ 15 kg/ha in the soil at planning in the furrows.

2. Spray the crop with Imidacloprid 17.8 SL @0.5 - 0.6 ml/liter water.

Cutworm in the potato field.
Among the different species of cutworm, the A. ipsilon is the most common and devastating one. The caterpillar cut the young seedling at the base near the soil.

Cutworm Control in potato field.
Apply Phorate 10 G @ 15-20 kg/ha in the soil before sowing.

Beetle in the potato field.
It is a polyphagous insect and both larvae and adults feed on the leaf chlorophyll in a characteristic manner causing leaf skeletonization.

Beetle Control in the potato field.

Spray Malathion 50 EC @1.5-2.0 ml/ liter water.

Leaf Eating Caterpillar in the potato field.
Bihar hairy caterpillars, tobacco caterpillars and Lucerne caterpillars feed on the foliage gregariously and defoliate the plants.

Control - Spray Malathion 50 EC @1.5-2.0 ml/ liter water.

Potato Tuber moth.
It is a serious pest of potato both infield and storage. After hatching, the caterpillar bores and makes tunnels into the tubers. The infested tubers ultimately rot and become unfit for human consumption. The caterpillars continue to feed in the storage.

Control.

1.Select healthy and insect free tubers for planting.

2. Proper earthing should be done so that tubers are not exposed to oviposition female moths.

3. Spray the crop with Basillus thuringiensis (0.05%)

4. Sort out the affected tubers before storage.

Potato Tuber moth

5. Treat the gummy bags used for storage with Neem Kernal extract at 10%

White Grub in Potato.
The attack of white grub is mainly confined to hill regions. Anomala dimidiata is the most common white grub infestation of the potato.

Control.

  1. Follow clean cultivation procedures.

2. Incorporate Phorate 10 G @ 15 - 20 kg/ha in the soil before planting.

Root-knot nematode in Potato.
Galls are formed on the attacked roots. The infected plants grow slowly and remain stunted and weak. Leaves become yellow, wilt and drop.

Control.

  1. Give deep and thorough summer cultivation.

2. Locate the resistant varieties.

3. Follow crop rotation excluding Solanaceae crops.

4. Grow trap crops like marigold.

5. Apply Phorate 10 G @ 20-25Kg/ha in the soil.

6. Fumigate the soil with MNemagon @ 20-25 Kg/ha.

Golden Cyst Nematode in potato.
In India, this nematode is confined to only the Nigiri hills of Tamil Nadu. Additional rootlets are produced near the soil surface in infected plants. The leaves turn yellow and finally die.

Control.
1. Follow plant quarantine measures.

2. Give deep ploughing during summer.

3. Grow resistant varieties like Kufri Swarna, Kufri Sherpa and Kufri Thanamali.

4. Follow crop rotation avoiding Solanaceae crops.

5. Incorporate Phorate 10 G @ 20 -25 kg/ha at the time of planting in the furrows.

6. Fumigate the soil with Nemagon @ 20-25 kg/ha.

Fungal Disease in Potato.

Early Blight of Potato.
The disease is characterized by the appearance of dead spots with concentric rings on the leaves. The fungus is a soil born and warm moist weather that is favorable for the development and spread of disease.

Control.

  1. Grow resistant /tolerant varieties like Darjeeling Red Round, Kufri Jeevan, Kufri Naveen, Kufri Sinduri, Kufri Pukharaj, Kufi Himso etc.

2. Follow crop rotation.

3. Adopt Phytosanitary measure.

4. Spray Dithane M-45 or Captan @ 0.25% at 10 days Interval.

Early Blight in Potato.

Late Blight of Potato.
Circular or irrigation water-soaked spots appear on the leaves which soon turn to brownish-black lesions. These lesions enlarge and coalesce, killing the entire leaf. White downy growth of fungus appears on the underside of leaves. Decayed leaves emit offensive odor. The cool moist environment is favorable. The primary source of inoculum is the disease infected seed tubers.

Control.
1. Use healthy, disease-free and certified seed tubers for planting.

2. Locate resistant/ tolerant varieties.

3. Make four prophylactic sprays of Blitox 0.3%  or Dithane M-45 days interval.

4. Spray the crop with Dithane M-45 0.25% at 15 days interval starting from the appearance of the disease.

Black Scurf of Potato.
Superficial growth of fungus develops on the infected tubers. The black colored sclerotia bodies are formed on the skin of tubers whereas the flesh remains unaffected. The affected plants are killed and a stem canker may be formed, therefore, it is also known as Rhizoctonia stem canker. The source of inoculum is soil and infected tubers.

Control.
1. Use disease-free seed tubers for planting.

2. Follow clean cultivation.

3. Grow resistance varieties.

4. Adopt crop rotation with maize, sunhemp, dhaincha , etc.

5. Incorporate Brassicol and sawdust @ 30 kg and 25 q/ha respectively in the soil at the time of planting.

6. Allow dipping the seed tubers in Agallol-3 or Aretan @ 0.3% for 10 minutes before planting.

7. Dip the seed tubers in 1 % acetic acid having 0.05% zinc sulphate before storage.

Black Scurf of Potato.

Charcoal Rot of Potato.
The stem of the infected plants rot and skin turns ash-colored. In the case of tuber rot, small black spots develop at the site of lenticels and eyes. Tissues to a depth of 2-5 mm turn black and become unfit for consumption. The pathogen is soil as well as tuber born. Dry and warm (28-35 degree Celsius ) weather is favorable for the development and growth of fungus.

Control.
1. Obtain disease-free tubers from hilly areas for planting.

2. Keep the soil moist by frequency irrigation to lower the soil temperature.

3. Grown early maturing variety.

4. Harvest the crop before the soil temperature.

5. Treat the seed tubers with Agallol-6 or Aretan @ 0.25% before storage.

Powdery Scab of Potato.
The small, smooth, circular and light brown lesions develop on the surface of fibers which are later raised as pimples. Finally, the pustules burst and release a black-brown powdery mass of fungus. The disease is restricted to only hilly and valley regions.

Control.
1. Select health, disease-free and certified seed tubers for planting.

2. Dip the seed tubers in Agallol-3 @ 0.3% for 10 minutes or mercury chloride solution@ 0.1% for 1.5 hours before planting.

Powdery Scab of Potato.

Wart of Potato.
It is a serious soil-borne disease but restricted to only Darjeeling hills (West Bengal) and surrounding areas. The disease attacks all underground parts except roots. Affected parts exhibit lumpy or warty outgrowth. The wart is distorted, proliferated branched structure grown together into a mass.

Control.
1. Follow quarantine measures.

2. Avoid cultivation of potato on wart affected soils.

3. Grow wart resistant/tolerant varieties.

4. Soil Sterilization Should be done with copper sulphate or 5% formalin before planting.

Sclerotium rot of Potato.
The characteristic symptoms of the disease are wilting of infected plants and rotting of tubers during transport and storage. It is prevalent in warmer India.

Control.
1. Follow long term rotation with maize, sorghum, etc.

2. Before planting dip the seed tubers in Agallol or Aretan at 03.% for 10 minutes.

Bacterial Disease of Potato

Bacterial Wilt  of Potato
It is characterized by the appearance of wilting, stunting and yellowing of foliage followed by the collapse of the plants. Browning of the xylem in the vascular bundles occurs. The infected tubers are discolored. The pathogen is soil-born.

Control.
1. Use healthy and disease-free tubers for planting.

2. Follow at least 3 years of crop rotation with maize, cowpea, soybean, French bean and grasses.

3. Use a disinfected knife for cutting tubers.

4. Treat the seed tubers with Streptocycline solution (0.02%) for 30 minutes before planting.

Common Scab of Potato.
The infected tubers show the superficial rough areas of corky tissue, sometimes raised above and often slightly below the healthy skin in case of shallow scab. In a deep scab, lesions are 1-3 mm deep but darker than a shallow scab. The organism survives for many years in the soil and remains active at a Ph range below 5.4 or above 7. Low soil moisture also favours the multiplication of pathogens.

Control.
1. Grow resistant/ tolerant varieties.

2. Locate healthy and disease-free tubers for planting.

3. Follow 4-year crop rotation excluding sugar beet and carrot.

4. Treat the seed tubers in the solution of Agallol- 6 or Emisan-6 at 0.25% for 30 minutes before planting.

5. Keep the field in well-irrigated condition during tuberization.

6. Maintain the soil reaction between 5.0 and 5.3.

Common Scab of Potato.

Soft Rot of Potato.
The infected plants remain dwarf and stunted. Leaves turned yellow and curled. Brown-black or jet black rotten areas develop on the base of the stem called “black leg”. The affected tubers become dark both inside and outside. The internal tissues become soft resulting in the disintegration of the whole tuber. The pathogen is also prevalent in storage.

Control.
1 Select disease-free seed tubers for planting.

2. Follow long term crop rotation.

3. Uproot affected plants and destroy them.

4. Treat the seed tubers in Streptocycline solution at 0.01% before planting.

- Advertisement -
KrishiHub

Written by KrishiHub

Technology-driven Agricultural ecosystem for Indian farmers
You've successfully subscribed to KrishiHub Agri Library
Great! Next, complete checkout to get full access to all premium content.
Welcome back! You've successfully signed in.
Unable to sign you in. Please try again.
Success! Your account is fully activated, you now have access to all content.
Success! Your billing info is updated.
Billing info update failed.