Disease of Cassava By B. Sivamonica

1. COLLEGE OF AGRICULTURAL TECHNOLOGY
Affiliated to Tamil Nadu Agricultural University, Coimbatore
Kullapuram, Via Vaigai dam, Theni-625 562
CASSAVA LEAF SPOT
STUDENT COURSE TEACHER
Miss. SIVAMONICA .B Dr. PARTHASARATHY. S
ID. No. 2015021117 Asst. Prof., (Plant Pathology)

2. OCCURRENCE:
• Found in almost all the main plantation areas
(Jameson, 1970). This disease was first found in east
Africa in 1885, and later occurred in India in 1904,
and in the Philippines in 1918.
• It is extensively found in South India especially in
Tamil Nadu and Kerala.

3. DISTRIBUTION:
• Asia
• Africa – 1885 first identified
• South America
• Central America

4. ECONOMICAL LOSSES:
• It causes tuber loss to about more than 10%.
• Found more loss in China where 70% of production
is used for ethanol.

5. SYMPTOMS:
• Large brown or greyish brown spots which are
spherical or angular.
• Borders of the spots are dark brown and the centre a
lighter shade of brown or grey.
• In severe infections the leaf spots are surrounded by
a yellow halo caused by a toxin produced by the
advancing mycelium (Teri et al., 1978).
• Older leaves are more readily attacked than young
ones.
• The diseased plant shows poor growth and yield
undersized tubers.

6. Brown color spot on leaves
©pestnet.org

7. Shot holes with halo
@ CTCRI tools

8. PATHOGEN:
Cercosporidium henningsii (Allescher)
Mycosphaerella henningsii (Sivanesan – Perfect
stage)
Conidia:
C. caribeaea – small, angular, snowwhite spots,
hyaline conidia
C. henningsii - thin walled, septate, clavate and
olivaceous in colour, measures 30-35 x 4-6 microns

9. SYSTEMATIC POSITION:
Kingdom : Fungi
Phylum : Ascomycota
Subphylum : Pezizomycotina
Class : Dothideomycetes
Subclass : Dothideomycetidae
Order : Capnodiales
Family : Mycosphaerellaceae
Genus : Mycosphaerella
Species : M. henningsii

10. MODE OF SPREAD:
• Cassava is a long duration crop hence these fungi can
easily survive and reach a newly planted crop.
• Debris of diseased foliage can also harbor stomata
and conidia of these fungi.
• Conidia – dispersed through wind and rain splashes.

11. FAVORABLE CONDITIONS:
• Day temperature of 80-90 ˚F and night temperature of
60˚F favours disease development.
• Warm humid and wet conditions.

12. IDM:
CULTURAL METHODS:
• Make use of disease free cuttings and maintain
hygienic conditions in field.
• Adopt resistant varieties.
• Allow wide spacing between plants and plant early in
the wet season so that crops gain strength before
reaching susceptible stage (6-8 months).
• Rake and burn fallen manioc leaves or bury them.
• Crop rotation for every 3 to 5 years.

13. CHEMICAL METHODS:
• It is controlled with Thiophanate 0.20 %,
chlorothalonil.
• Use of copper fungicides are also recommended.
• If severe sprayings of Dithane M-45 or Dithane Z -78
of 0.2 to 0.3 percent given at about 10 days interval.
BIOLOGICAL METHODS:
• No biological methods still available to control.