MORPHOLOGICAL AND TAXONOMICAL CHARACTERS OF LATE BLIGHT OF POTATO

1. PRESENTED BY
A.TAMIL SELVAn
TOPIC: MORPHOLOGICAL AND TAXONOMICAL CHARACTERS OF
LATE BLIGHT OF POTATO

2. Causal Organism:Phytophthora infestans
ORIGIN: Central Mexico rather than Andes
 The pathogen was first described by
M.J.Berkeley in the 1846 and subsequently
named Phytophthora infestans by Anton de
Bary in the 1870

3. PATHOGEN: Phytophthora infestans
Domain: Eukarya
Kingdom: Chromista
Phylum: Oomycota
Class: Oomycetes
Sub class: Perenosporomycetidae
Order: Pythiales
Family: Pythiaceae
Genus: Phytophthora
Species: P. infestans

4. General Characters of Pythiales
Coenocytic
Inter –intra cellular
Paragynous antheridium
Fertilization takes place in large number
of species

5. Characters of Phytophthora infestans
Water mold
Mycelium: Hyaline, aseptate, branched, inter cellular
Cell wall is made up of cellulose
Sporangiophore – zig zag in shape,
 Dicotomously brached ,
 Determinate type
 Sexual spore:Oospore
 Asexual spore: Zoospore

6. Phytophthora infestans
Pear shape or lemon shaped sporangia with a
papilla
Zoospores are formed in sporangium itself
Both direct and Indirect germination of
sporangia
Papilla

7. Pytophthora infestans
Amphigynous antheridium
Sexual spore- Oospore

8. Life cycle of Pytophthora infestans
Indirect germination
Cool,12-15 C
Sporulation
at 15 25 C-
0
0
0

9. Symptoms of Phytophthora diseases
 Dark brown to black water soaked lesions
develop on upper surface of leaves.
 Lower surface shows white velvet growth.
 Rotting of leaf, petiole and stem and results in
death.
 Infected plants emit foul odour followed by
rotting of tuber.`

10. Symptoms of Phytophthora diseasesLate blight of potato:

11. Causes of Phytophthora infestans
 In 1845- Irish Famine, late blight of potato caused by Phytophthora
infestans
 Ireland- approximately 1 million people lost their lives due to
starvation
 People shifted to maize cultivation
 Million of people emigrated from Ireland
 To North America which include John Fitzgerald Kennedy, the 35 th
president of USA

12. Favourable Condition Of Phytophthora
 The pathogen is favored by Moist,cool environments
 Sporulation is optimal at 12-18 C in water-saturated
or nearly saturated environments
 Zoospore production is favored at temperatures below
15 C.
 Lesion growth rates are typically optimal at a slightly
warmer temperature range of 20 - 24 C
0
0

13. Management Of Late Blight Of Potato
 Protective spraying with Mancozeb or Zinbe 0.2 %
should be done to prevent infection of tuber
 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 Alenkar,Kufri khasi Garo and Kufri
Moti

14. REFERENCE:
 Late blight of potato - TNAU Agritech Portal
www.agritech.tnau.ac.in