FOR DOWNLOAD CONTACT - eduvish24@gmail.com FUNGAL DISEASES OF POTATO This ppt includes major fungal disease of potato includes Late blight of potato,Early Blight of potato, Black scurf of potato,Leaf blotch of potato and their symptoms , pathogenic characters, epidemiology, management like cultural and chemical management.

1. FUNGAL DISEASES OF
POTATO
PRESENTED BY ,
VISHALI NS

2. FUNGAL DISEASES OF POTATO
➢ Late blight of potato
➢ Early Blight of potato
➢ Black scruf of potato
➢ Leaf blotch of potato

3. LATE BLIGHT -Phytopthora infestans
ECONOMIC IMPORTANCE
➢ Historically and pathologically it was the most important disease.
➢ This was the disease responsible for the famous famine in Europe called
Irish famine during 1845- 46.
➢ In India it was first introduced to Nilgiri hills between 1870 and 80.
➢ A severe epidemic occurred first in Nilgiri in 1961.
➢ The main loss in yield is due to defoliation and haulm destruction. Blight
affected tubers rot in the field and storage

4. SYMPTOMS
➢ It affects leaves, stems and tubers.
➢ Water soaked spots appear on leaves, increase in size, turn purple brown&
finally black colour
➢ White growth develops on under surface of leaves.
➢ This spreads to petioles, rachis& stems. It frequently develops at nodes.
➢ Stem breaks at these points and the plant topples over.
➢ In tubers, purplish brown spots and spread to the entire surface on cutting, the
affected tuber show rusty brown necrosis spreading from surface to the center.

7. PATHOGEN CHARACTER
➢ Mycelium : hyaline ,endophytic mycelium , coenocytic ,highly branched
inter- and intracellular.
➢ Sporangiophores: hyaline ,branched with characteristic swollen ends
where the lemon-shaped
➢ Sporangia are produced, arise in cluster through stomata.
➢ Sporangia pear shaped ,hyaline ,papillate ,multinucleate
➢ Zoospores biflagellate produced at favourable conditions

8. MODE OF SPREAD AND SURVIVAL:
➢ The infected tubers and the infected soil may serve as a source of
primary infection.
➢ The diseased tubers are mainly responsible for persistence of the disease from
crop to crop.
➢ The air borne infection is caused by the sporangia.
EPIDEMIOLOGY :
➢ RH->90% , Temp.-10-25°C and Night temperature:10°C.
➢ Cloudness before rainfall and Rainfall at least 0.1mm and subsequent days
after rainfall.

9. MANAGEMENT
➢ Seed material should be selected from disease free crop in disease free area.
➢ Field sanitation
➢ Wider spacing.
➢ Reduced nitrogenous fertilizers to avoid overcrowding canopy
➢ Tuber contamination is minimized if injuries are avoided at harvest time and storing of
visibly infected tubers before storage.
➢ The resistant varities recommended for cultivation are Kufri Naveen, Kufri Jeevan,
Kufri Alenkar, Kufri Khasi Garo and Kufri Moti

10. CHEMICAL MANAGEMENT
➢ Dipping the seed tubers in fungicidal solutions like COC or 1% Bordeaux
mixture.
➢ Immediately after cutting, treat seed with a recommended mancozeb-based seed
piece fungicide.
➢ Spraying: Earlier days 1% BM sprayed in early stages at fortnightly interval when
the crop is at 15-20 cm ht.
➢ If weather is more favourable once in 7 days Mancozeb 0.25% is effective.
➢ Other fungicides recommended are difolatan, zineb 0.2% and Duter 0.1 – 0.2%,
Daconil 0.1% , COC (0.25) @ 1.5 – 2.5 kg / ha.

11. EARLY BLIGHT - Alternaria solani
➢ Early blight is a very common disease of potato and is found in most
potato growing areas.
➢ This is one of the common diseases of potato and is worldwide in tits
distributors.
➢ In India it is serious on hills as well as on the plains.
➢ It is more common in rabi crop than in Kharif crop.
➢ It appears early in the season (3-4 weeks after sowing)

12. SYMPTOMS
➢ Initial infection usually occurs on the older, lower leaves then progresses up
the plant.
➢ Brown-black necrotic spot-angular, oval shape characterized by concentric
rings.
➢ Concentric rings of slightly raised and depressed dead/brown leaf tissue give
the lesions a “bull’s eye” appearance and produce a ‘target spot’ effect.
➢ Several spot coalesce & spread all over the leaf.
➢ Shot holes on fruits.

14. PATHOGEN CHARACTER
➢ Mycelium: septate, branched, light brown
which become dark at age, intercellular and
later intracellular
➢ Conidiophores - dark coloured emerge
through stomata.
➢ Conidia - born in chain, club – shaped,
muriform with 5-10 cross septa and 1-5
longitudinal septa with long beak.

15. MODE OF SPREAD AND SURVIVAL
➢ The conidia and the mycelium in the soil or in the debris of the affected plants
can remain viable for more than 17 months.
➢ Primary infection:
○ These conidia or the new conidia found on the overwintered mycelium
➢ Secondary infection :
○ The conidia formed on the spots developed due to primary infection are
disseminated by wind to long distances.
○ The conidia from the affected plant may also be disseminated to the
adjoining plants by rain and insects..

16. EPIDEMIOLOGY
➢ Dry warm weather with
intermittent rain.
➢ Poor vigor.
➢ Temperature: 25-30°C.
➢ Poorly manured crop.

17. MANAGEMENT
➢ Disease free seed tubers should be used for planting.
➢ Removal and destruction of infected plant debris should be done because the
spores lying in the soil are the primary source of infection.
➢ Very early spraying with Zineb or captan 0.2% and repeating it for every 15
– 20 days gives effective control.
➢ The variety Kufri Sindhuri possesses a fair degree of resistance.

18. Black scurf: Rhizoctonia solani
SYMPTOM:
➢ Black speck, black speck scab, russet scab on tubers.
➢ At the time of sprouting dark brown colour appear on the eyes.
➢ Affected Xylem tissue causes to wilting of plants.
➢ Infected tuber contains russeting of the skin.
➢ Hard dry rot with browning on internal tissue.

21. PATHOGENIC CHARACTER
➢ The fungus is characterized by the right angle branching of the hyphae.
➢ The hyphae are clear in young, but turn brown with age
MODE OF SPREAD AND SURVIVAL:
➢ Rhizoctonia diseases are initiated by seed borne or soil borne inoculum.
➢ The sclerotia on the seed tubers is the principal source of infection of the
subsequent crop raised with these tubers.
➢ On return of favourable conditions the mycelium present in the soil may
develop producing new hypae.

22. EPIDEMIOLOGY
➢ Seed tubers are source of spread.
➢ Moderately cool, wet weather and temp 23 °C are the favourable for the
development of disease.
➢ Disease develops more in sandy soil than clay.
➢ Cool temperatures, high soil moisture, fertility and a neutral to acid soil (pH 7
or less) are thought to favor development of Rhizoctonia disease.

23. MANAGEMENT
➢ Disease free seed tubers alone should be planted.
➢ If there is a slight infection of black scurf that can be controlled by treating seed
tubers with mercuric chloride solution for 1.5 hr with acidulated mercuric
chloride solution for 5 min.
➢ Treating the soil with pentachloronil trobenzene at the rate of 70 kg/ ha
lowers the incidence of the disease, but it is too expensive and cumbersome.
➢ Well sporulated tubrs may be planted shallow to control disease.
➢ The disease severity is reduced in the land is left fallow for 2 years.

24. LEAF BLOTCH: Cercospora concors
SYMPTOMS
➢ Circular or irregular pale green or light purple spots first appear on lower
leaves.
➢ The spots may be covered with grayish fungal growth.
➢ The spots enlarge and coalesce to form big blotches on the lamina.

25. PATHOGENIC CHARACTER
➢ Conidiophores and conidia form on the underside of the lesions, giving
the lesions a mildewed appearance similar to late blight
➢ The conidiophores were irregular in width, grayish, and highly branched.
➢ The conidia were numerous, light to dark, straight or slightly bent,
cylindrical or obclavate, with conspicuous scars, and zero to six septa.

26. MODE OF SPREAD:
➢ Infected plant debris act as primary source
➢ Sec. Spread through conidia carried by wind, rain etc.
EPIDEMIOLOGY:
➢ Cool and wet weather favour disease development.
➢ Optimum temp for germination of conidia 20 C

27. REFERENCES
https://agritech.tnau.ac.in/crop_protection/crop_prot_crop%20diseases_veg_potato_4.html
Arora R.K , S. M. Paul Khurana.2004 .Major Fungal and Bacterial Diseases of Potato and their Management.Fruit and
Vegetable Diseases.Volume 1.ISBN : 978-1-4020-1976-0.
http://vegetablemdonline.ppath.cornell.edu/factsheets/Potato_LateBlt.htm
https://www2.ipm.ucanr.edu/agriculture/potato/Early-Blight/
https://www.biologydiscussion.com/plants/plant-diseases/early-blight-of-potato-with-diagram-plant-diseases/64337
http://www.apsnet.org/edcenter/intropp/lessons/fungi/ascomycetes/PublishingImages/PotatoTomato01sm.jpg
http://agropedia.iitk.ac.in/content/black-scurf-potato
Tian SM, Ma P, Liu DQ, Zou MQ. First Report of Cercospora concors Causing Cercospora Leaf Blotch of Potato in Inner
Mongolia, North China. Plant Dis. 2008 Apr;92(4):654. doi: 10.1094/PDIS-92-4-0654C. PMID: 30769662.

28. THANK YOU