IDM in potato Integrated Disease Management

1. Integrated Disease management of Potato
R. Yonzone
Asst. Professor

2. Major Diseases of Potato
1. Bacterial wilt :Ralstonia solanacearum- Pseudomonas solanacearum
2. Late Blight: Phytophthora infestans
3. Early Blight: Alternaria solani
4. Common Scab: Streptomyces scabiei
5. Black Scurf: Rhizoctonia solani
6. Black Leg and Soft rot: Erwinia carotovora
7. Black Heart : Disorder
8. Leaf curl disease: Viral disease

3. Bacterialwilt :Ralstonia solanacearum-
Pseudomonas solanacearum
Symptoms:
 The symptoms of bacterial wilt infection can be
seen on all parts of infected plants.
 Infected plant begins to wilt, starting from the tips
of the leaves or where the stems branch out, and
then spreads to all parts of the plant.
 Leaves become yellow at their bases, then the
whole plant wilts and dies.
 When Stems are cut a brown colored ring will be
visible.
 When a tuber is cut in half, black or brown rings
will, however, be visible.
 If left for a while or squeezed, these rings will
exude a thick white fluid.

4. Late Blight: Phytophthora infestans
Symptoms:
 This disease damages leaves, stems and
tubers.
 Affected leaves appear blistered as if scalded
by hot water and eventually rot and dry out.
 When drying out, leaves turn brown or
black in color. When infections are still
active, spots appear on the underside of
leaves blanketed in what looks like flour.
 Affected stems begin to blacken from their
tips, and eventually dry out.
 Severe infections cause all foliage to rot, dry
out and fall to the ground, stems to dry out
and plants to die.
 Affected tubers display dry brown-colored
spots on their skins and flesh.

5. Early Blight: Alternaria solani
Symptoms:
 The early blight is first observed on the
plants as small, black lesions mostly on
the older foliage.
 Spots enlarge, and by the time they are
one-fourth inch in diameter or larger,
concentric rings in a bull's eye pattern
can be seen in the center of the diseased
area.
 Tissue surrounding the spots may turn
yellow. If high temperature and humidity
occur at this time, much of the foliage is
killed.
 Lesions on the stems are similar to those
on leaves, sometimes girdling the plant if
they occur near the soil line.

6. CommonScab: Streptomyces scabiei
Symptoms:
 Pathogen infects young developing
tubers through the lenticels and
occasionally through wounds.
 Symptoms of common potato scab
are quite variable and are manifested
on the surfaceof the potato tuber.
 The disease forms several types of
cork-like lesions including surface.
Damaged tubers have rough, cracked
skin, with scab-like spots.
 Severe infections leave potato skins
covered with rough black welts.
Initial infections result in superficial
reddish-brown spots on the surface
of tubers.
 As the tubers grow, lesions expand,
becoming corky and necrotic.

7. Black Scurf: Rhizoctonia solani
Symptoms:
 Rhizoctonia canker occurs when stolons
contact soil borne fungal bodies.
 Pathogen infects plant tissue and causes
stolon blinding thus reducing tuber
production and yield.
 It also infects tubers causing black scurf
but this is purely cosmetic, reduces tuber
appearance and does not reduce yield.

8. Black Leg and Soft rot: Erwinia
carotovora
Symptoms:
 Black leg is a rot of the lower stem
region.
 This is encouraged by cool, damp
conditions.
 Soft rot occurs when the bacteria
gains access to the tuber through
wounds & other entry points.
 Symptom can range from cultivator
damage to fungal lesions.
 bacteria dissolve the cell walls and
liquefy the tuber invaders.
 No distinct smell is present in true
soft rot.

9. Black Heart : Disorder
Oxygen deficiency of internal tuber
tissue
Disease symptoms:
 Black heart occurs primarily in
storage when the tubers do not
receive enough oxygen.
 Blackening of the tuber center
follows acute oxygen deficiency
associated with either low
temperature in confined storage or
high field soil temperatures.
 The tissue dies from the inside out
and turns jet black.
 Smell is absent.
 Affected tubers rot later.

10. IDM METHODS
1. Seed Quality and Certification:
 Disease-free stem cuttings or tiny pieces of meristem tissue are cultured and
propagated under sterile conditions to produce large numbers of disease-free plantlets
or mini tubers
 Certified seed tubers production
2. Biological Control :
 Bacteria antagonistic to Erwinia caratovora are being developed as seed piece
treatments for reducing seed piece decay and blackleg.
 Among rhizobacteria Agrobacterium radiobacter, Bacillus subtilus and Pseudomonas
spp. are antagonistic to potato cyst nematodes (Globodera pallida and G. rostochiensis
although Pasreuria penetrans attach PCN.
 Larkin reported that soil-application of aerated compost tea (ACT) and the combination
of ACT with a mixture of seven different micorrhizal fungus species belong to Glomus
spp. reduced stem canker, black scurf, and common scab on tubers by 18% - 33% and
increased yield 20% - 23% in the barley/ryegrass rotation, but not in the other
rotations

11. 3. Resistant Cultivars:
 Cultivars resistant or tolerant to disease can help reduce losses caused by some
soil-borne pathogens and provide long-term, economical protection.
 New potato breeding selections are assessed for resistance to several viruses,
leaf-roll net necrosis, root-knot nematodes, Verticillium wilt, scab, blackleg, early
blight, and several physiological disorders.
 Kufri Ashoka, kufri Chandramukhi, Kufri Bahar and Kufri Pukhraj varieties of potato
are highly susceptible to late blight.
 Kufri Jyoti, Kufri Sutluj and Kufri Badshah are moderately resistant.
 Central Potato Research Institute, Shimla has released potato varieties like, Kufri
Chipsona-1 and Kufri Chipsona-2 for cultivation in northern plains of the country.
 These varieties are also moderately resistant to late blight and are suitable for
processing.

12. 4. Chemical Control with Pesticides :
 Fungicides can reduce damage caused by certain foliar pathogen such as
powdery mildew, late blight, and severe early blight.
 To be effective, they usually must be applied before infection occurs or when
the disease just begins to develop.
 Soil fumigants may be used to control nematodes or Verticillium.

13. 5. CULTURAL PRACTICES:
 Cultural practices including seed selection and handling, planting, irrigation,
fertilization, vine killing, careful harvesting methods have a significant impact.
 Water management helps prevent Rhizoctonia and piece decay early in the growth of
the plant, reduces tuber malformation and symptoms of Verticillium wilt during the
season, the severity of scab, and helps prevent tuber rots as plants mature and die.
5.1 Sanitation:
 Potato cull piles should be destroyed or sprayed to ensure that no Phytophthora
sporangia will be blown from there to the potato plants in the field.
 Waste potatoes must be handled correctly to eliminate these and other potential
dangers.
 Tubers should be cut with disinfested knifes to reduce spread of ring rot among seed
pieces and the seed pieces usually treated with a fungicide, a bactericide, and an
insecticide to protect them from pathogens on their surfaceor in the soil.

14. 5.2.CropRotation:
 Crop rotation is useful for control of soil-inhabiting pathogens that have limited host
ranges and require host plant residues for survival.
 Rotation is less effective for pathogens such as Verticillium spp. or Phytophthora
erythroseptica, which can survive in the soil for a long time in the absence of host.
 Rotation with legumes, corn, or other unrelated crops will reduce the population of
soil borne potato pathogens.
5.3. Seed Treatment:
 Seed piece decay frequently involves a Fusarium fungus acting synergistically with
bacteria.
 Therefore, chemical seed treatments, which primarily act as fungicides, are useful
when conditions favor development of Fusarium on seed pieces.

15. 5.4. Irrigation:
 Too little water will reduce yields, induce tuber malformations, or increase severity of
scab or Verticillium with symptoms.
 Sprinkler irrigation provides conditions in the canopy that are favorable for certain
diseases such as early blight, late blight, and white mold (Sclerotinia spp.).
 To reduce spread of these diseases, foliage should be allowed to dry out between
irrigations.
5.5. Fertilization
 Recommended fertilizer should be used.
5.6. Harvest:
 Before harvest, the infected plants must be killed with chemicals to destroy late
blight inoculum that could be in contact with the tubers when they are dug up
5.7. Storage:
 Uniform airflow throughout the pile is important

16. Stages of crop and Stratigies
1. Pre sowing:
2. Sowing

17. 3. Vegetative/ seed/tuber stage
4. Tuber initiation stage:
 Leaf spot complex: Follow common cultural, mechanical and biological practices
 Early blight: Follow common cultural, mechanical and biological practices
Chemical control: Mancozeb 75% WP@ 600-800 g in 300 l of water/acre or
hexaconazole 2% SC @ 1.2 l in 200 l of water/acre (second spray after 21 days interval)
or kitazin 48% EC @ 0.20% or 200 ml in 200 l of water or propineb 70% WP @ 300 g in
100 l of water or 0.30%

18.  Late blight: • Follow common cultural, mechanical and biological practices
 Cultural control:
• Use short-duration varieties.
• The model specifies that 7 days moving sum of RH > 85% for at least 90 hr coupled
with a 7 day moving sum of temperature between 7.2 and 26.6°C for at least 115 hr
would predict appearance of late blight within 10 days of satisfying the conditions.
 Chemical control:
• Spray captan 50% WG @ 600 g in 200 l water (second spray after 5 days interval) or
captan 50% WP @ 1 Kg in 300- 400 l water/acre or captan 75% WP @ 666 g in 400 l
water/acre (second spray after 8 days interval) or chlorothalonil 75% WP @ 350-500 g
in 240-320 l of water/acre (second spray after 14 days interval) or copper oxychloride
50% WP @ 1 Kg in 300-400 l of water/acre

19. 5. Vegetative and tuber development
stage

20. 6. Harvesting