PATHOLOGY

1. COLLEGE OF AGRICULTURAL TECHNOLOGY
Affiliated to Tamil Nadu Agricultural University, Coimbatore
Kullapuram, Via Vaigai dam, Theni-625 562
WHITE BLISTERS OF HORTICULTURAL
CROPSOF
STUDENT COURSE TEACHER
Mr, RAHUL. A Dr. PARTHASARATHY. S
ID. No. 2015021102 Asst. Prof., (Plant Pathology)

2. RADISH
White blister or Rust: Albugo candida
Hosts :
Cabbage, Mustard, Radish and Turnip

3. DISTRIBUTION
• It has a cosmopolitan distribution and is known from
many countries.
• Where cruciferous crops are grown in Europe, Asia,
Africa, Australia, North, Central and South America.

4. SYMPTOMS
Two types of infection:
Local infection:
Isolated pustules or sori develop in leaves
and stems, pustules merge to form larger
patches. Host epidermis rupture after maturity
of pustules.
Systemic infection:
When young stems and flowering parts are
infected it becomes systemic. Stimulates
hypertrophy and hyperplasia.

5. • Results in enlarged and variously distorted
organ mostly flower parts sepals become
enlarged to several times than the normal
sepals.
• Petals enlarge and become green pistils and
anthers are distorted.
• Seed development is arrested.

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7. PATHOGEN CHARACTER
• Pathogen is an obligate parasite.
• Pathogen produces sporangia.
• Mycelium is intercellular producing knob
shaped haustoria in the host cells.
• Each sporangium has 4 to 8 zoospores.
• Sexual spore is tuberculate oospore.

8. SYSTEMIC POSITION
• PHYLUM : Heterokontophyta
• CLASS : Oomycota
• ORDER : Peronosporales
• FAMILY : Albuginaceae
• GENUS : Albugo
• SPECIES : A. candida

10. FAVOURABLE CONDITIONS
• Rain splash of spores from soil onto the plant.
• Free water (dew, fog, irrigation or rain) on leaves and
stems.
• Spores germinate at temperatures between 1 to 20C, with
the optimum range being 10 to 15C
• The blisters can be become visible from 6 to 10 days after
infection.

11. MODE OF SPREAD AND SURVIVAL
Primary spread: Oospore
Secondary spread: Sporangia and Zoospores
Over wintering may be through oospores in
plant debris in the soil and mixed with seeds
and perennial mycelium in weed hosts are
primary source of inoculum.

12. SWEET POTATO
White blister or Rust:
Albugo ipomoea - panduratae

13. SYMPTOMS
• Presence of chlorotic or yellowish blotches,
initially roundish to angular where they are
limited by veins, on the upper surface of
leaves.
• On the lower surface, white creamy pustules
produced corresponding upper surface yellow
discolouration.
• Complete yellowing and premature shedding
of leaves.

14. https://images.app.goo.gl/tppzwskragm5hjux6

15. PATHOGEN CHARACTER
• The mycelium is intracellular with typical
knob like haustoria.
• The sporangiophores are hyaline, club shaped,
unequally curved at the base.
• The sporangia are produced in chains.
• They are short, cylindrical, with more rounded
terminal and smooth.
• The oospores are light yellowish brown with
papillate epispore and curved ridges.

16. SYSTEMIC POSITION
• SUPERPHYLUM : Heterokonta
• CLASS : Oomycetes
• ORDER : Albuginales
• FAMILY : Albuginaceae
• GENUS : Albugo
• SPECIES : A. ipomoeae - panduratae

17. MODE OF SPREAD
• Primary spread : Oospore
• Secondary spread : Zoospore

18. MANAGEMENT
• Regular spraying with Mancozeb 0.25 % effectively
controls the disease.
• Controlled watering - avoid night irrigations if
possible.
• Maintain good air flow within the crop to allow
leaves to dry off quickly and minimise ideal infection
conditions.
• Maintain a balanced nutrition program to reduce any
stress on the plant.

19. reREFERENCES
• agritech.tnau.ac.in
• Thind.T.S, Diseases of fruits and vegetables
and their management, Kalyani publishers,
New Delhi.
• Arun Arya, Tropical Fruits Diseases and
Pests,Kalyani publishers, New Delhi.