Minute,orange-yellow coloured,raised pustules appear with powdery masses on the lower surface and corresponding upper surface yellow colour leaves

1. CC
CCACASTOR RUST
OR
COLLEGE OF AGRICULTURAL TECHNOLOGY
(Affiliated to Tamil Nadu Agricultural University, Coimbatore-3)
Kullapuram (Po),ViaVaigai Dam, Theni-625 562
Course teacher: Student:
Dr. Parthasarathy. S Miss. C. Pon Alagammai.
Asst.Professor (Plant Pathology) 2015021095

3. Name of the disease :
Castor Rust.
Casual organism :
Melampsora ricini.

4.  Castor oil plant (Ricinus communis L.,
Euphorbiaceae) originates from tropical Africa and has
seeds that contain ricin, an extremely toxic protein.
 The seeds also yield oil, which has industrial and
medicinal uses.

5. • In Australia, castor oil plant is a weed in all States and,
in southern Australia, is grown as an ornamental.
• One rust, Melampsora ricini E.A. Noronha, has been
recorded on castor oil plant, in Africa, Asia and
southern Europe (Punithalingam 1968).

6. 1. M. ricini is known only in its uredinial
and telial states.
2. In Australia, M. ricini was first collected
(BRIP 25782) in Brisbane in August, 1999.
3. Within weeks the rust was found in Perth.

7. 4. Telia were observed as light brown spots, 0.5-
1.5 mm diameter, on the lower surface of young
expanding red leaves.
5. Teliospores are prismatic, 25-65 x 5-13 ym,
with walls 1-1.5 mm.
6. Expanding leaves with telia had few uredinia.

8. 7. At least seven other rusts of plants in the
Euphorbiaceae are known in Australia (J. Walker,
unpublished).
8. Of these, the rust on Euphorbia peplus L., a member
of the Melampsora euphorbiae Castagne complex (Sydow
& Sydow 1914), is most similar to M. ricini.

9. Significance:
 Controlling the rust with hyperparasites has been
attempted but not found to be economic importance.
 It is suggested that at the first sign of infection,
diseased leaves should be destroyed

10. Symptoms:
1. Minute, orange-yellow coloured,
raised pustules appear with powdery masses on
the lower surface of the leaves and the
corresponding areas on the upper surface of the
leaves are yellow.
2. Often the pustules are grouped in concentric
rings and coalesce together to for drying of leaves.

11. 3. Pale leaf spots eventually develop into spore-
producing structures called pustules.
4. The pustules are found most commonly on the
lower leaf surface and produce huge numbers of
microscopic spores.

12. 1.
5. Some cases there may be dozens of pustules on
a single leaf.
6.Severely affected leaves often turn yellow and
fall prematurely.

13. 7. Pustules also sometimes form on leaf stalks
(petioles), stems and, rarely, on flowers and fruit.
8. Heavy infection often reduces the vigour of
the plant. In extreme cases (e.g. with antirrhinum
rust) the plant can be killed.

14. Castor rust Uredospores

15. Etiology:
1. The hyphae of the causal organism
Melampsora ricini collect beneath the epidermis of the
leaf and form a minute cushion.
2. The uredospores arise beneath the epidermis on
the tips of branched hyphae.
3. Stout club-shaped paraphyses are also formed
in the sorus.

16. 4. At maturity the epidermis ruptures releasing
clouds of spores.
5. The uredospores are round or elliptic, warty and
orange in colour and measure 25-29 X 19-25µ.
6. They germinate by germ tube which comes out
from the pores and infects fresh leaves of castor.

17. 7. It was observed that the rust culture could not
be maintained on host plants under Delhi conditions
beyond the beginning of April because of rise in
temperature.
8. Melampsora ricini is pathogenic to Euphorbia
obtusifolia, E. ipecacuanha, E. giniculata and
E. marginata besides 24 strains and varieties of
R.communis.

18. Systemic position:
Kingdom: Fungi
Phylum : Basidiomycota
Class : Urediniomycetes
Order : Uredinales
Family :Melampsoraceae
Genus :Melampsora
Species : M.ricini.

19. Spread:
1. Chiefly by urediospores, and sometime by
winds.
Distribution:
1. The disease occurs in Bombay, Deccan
districts, Coimbatore and Nagpur.
2. It usually appears in Bombay between
November and February on castor sown in June.

20. 1. The damage caused by this disease was very
severe in moist localities and at places where the
disease appeared quite early.
2. In Hyderabad the disease appears only in
December when the capsule formation has already
started so that little damage is done to the crop.

21. Favorable condition:
Common in India – Nov-Feb-Annual crops.
Geographical distribution:
Africa (Algeria, Congo, Egypt, Ethiopia,
Kenya, Libya, Malawi, Morocco, Mozambique,
Rhodesia, Sudan, Tanzania, Uganda); Asia (Ceylon,
Cyprus, India); Europe (Italy, Lusitania, Portugal).
(From literature and Herb. IMI)

22. Hosts:
On Ricinus communis; also by inoculation on
1. Euphorbia geniculata,
2. E. ipecacuanha,
3. E. marginata and
4. E. obtusifolia.

23. Management:
• The disease is reported to be successfully controlled
by spraying the crop with fine sulphur powder @20-
30kg / hec.
• Spraying of Tridemorph 1 ml/litre of water or
Mancozeb 2.5 g/litre of water minimises disease
spread.