Agriculture

1. Symptoms and taxonomic characters of
Ustilago, Sphacelotheca,
Tolyposporium, Tilletia and
Exobasidium

2. Ustilago spp
• Smut pathogen
• 200 species on crop plants
• Name Ustilago from latin word ustus mean burnt –
black powdery mass of spores on host plant parts-
burnt appearance.
• U. tritici- Loose smut of wheat
• U. maydis- Maize smut

3. Loose smut of wheat
• Ear head emergence stage
• Emerge out earlier than
healthy one
• Smutted spikelet covered
by a silvery membrane
contains black dry
powdery mass of smut
spores.

4. Pathogen
• Facultative saprophytes
• Internally seed borne nature
Smut- teliospores- Olive brown,
Spherical or oval shape

5. U. maydis- Maize smut
Corn kernels to swell up into tumor-
like galls, whose tissues, texture and
developmental pattern are mushroom
like.
Galls are made up of hypertrophied
cells of the infected plant, along with
resulting fungal threads, and blue-
black spores.
Light greyish silvery appearance.
Other name: blister smut of maize,
boil smut of maize, common smut of
maize

6. Sphacelotheca (Sporisorium spp)
In Sorghum
• Grain smut/ Short smut/Covered smut - S. sorghi
• Loose smut- S. cruenta
• Long smut- S. echrenbergii
• Head smut- S. reilianum
Whip smut of sugarcane- S. scitaminae

7. Sorghum smut
Characters Grain smut/
Short
smut/Covered
smut
Loose smut Long smut Head smut
Symptoms All grains
smutted
Loose ear
head with all
smutted grains
Few grains are
smutted
Entire ear
head smutted
into single gall
Sori Oval/cyclinderi
cal, small
Oval/cyclinderi
cal, small
Cyclinderical
slightly curved
long
Very large
Spores Oval and brown
and smooth
walled
Spherical ,
dark brown
with pitted
walls
Globose,
Brownish
green with
warty walls
Spherical
angular, light
brown

8. Grain smut/ Short smut/Covered smut
The individual grain replaced by smut sori.
The sori are covered with a tough creamy skin.
Loose smut
Earhead gives a loose appearance than healthy.
The sorus is covered by a thin membrane which
ruptures very early, exposing the spores even as the
head emerges from the sheath.

9. Long smut
Sorus covered by thick creamy-
brown covering membrane
Head smut
Entire ear head into a smutted gall
appearance

10. Whip smut of sugarcane

11. Pathogen
Spores are echinulate, light
brown and spherical,
measuring 6.5 – 8.5 µ in
diameter.

12. Smut spore- teliospores
• Germination- Promycelium/metabasidium
• Meiosis – Diploid nuclei- 4 haploid nuclei
• Septum formation- 4 hyaline uninucleate
spores- called- sporidia

13. Sporidia cause systemic infection by
• Floral infection - cumbu (Tolyposporium
penicillariae)
• Seedling infection- Flag smut of wheat
(Urocystis tritici)
• Shoot infection- Sugarcane whip smut
(U.scitaminae)
• Embryo infection (ovariculous smut)- Loose
smut of wheat

14. Exobasidium vexans
Kingdom: Fungi
Phylum: Basidiomycota
Class: Exobasidiomycetes
Order: Exobasidiales
Family: Exobasidiaceae
Genus: Exobasidium
Species: E. vexans

15. Tea blister blight
• Small, pinhole-size spots are initially seen on young leaves less
than a month old.
• As the leaves develop, the spots become transparent, larger,
and light brown.
• After about 7 days, the lower leaf surface develops blister-like
symptoms, with dark green, water-soaked zones surrounding
the blisters.
• Following release of the fungal spores, the blister becomes
white and velvety.
• Subsequently the blister turns brown, and young infected
stems become bent and distorted and may break off or die.

17. Pathogen
• Hemibiotrophic
Asexual spore- Conidia
Conidia singly at tip of conidiophores, hyaline,
ellptical, slightly curved
Sexual spores- Basidiospore -Hyaline, ovate
single celled

18. Tilletia spp
• Tilletia indica and T. laevis - karnal bunt of
wheat
(T. indica- teliospores with warty (ridges on
their walls and T. laevis- smooth walled
teliospores)
• Tilletia horrida- paddy bunt

19. Tilletia indica
• Karnal bunt of wheat was first identified from
Botanical Research Karnal, Haryana in 1931 by
Mitra
• Partial bunt disease/ hill bunt/common bunt/
stinking smut
• 1847- named by Tulasne brothers to honour
Tillet (worked on stinking smut of wheat)

20. • The smut fungus Tilletia indica, a basidiomycete,
invades the kernels and obtains nutrients from
the endosperm, leaving behind waste products with
a disagreeable odor that makes bunted kernels too
unpalatable for use in flour or pasta .
• Wheat containing 3% bunted grains is unfit for
human consumption.
• Highly infected grains show remarkable decrease in
the seed viability.
• The disease is characterized by a fishy odour, which is
due to the presence of trimethylamine secreted by
teliospores.

21. • Karnal bunt pathogen is seed-, soil- and air-
borne.
• The disease reduces seed quality, changes the
chemical composition of infected grains, and
makes seed inedible.

23. Pathogen
• Teliospores- reticulate, echinulate, verrucose,
tuberculate to smooth.
• Teliospores germinate and form holobasidium
with multiple retraction septa and a whorl of
aerial primary sporidia at terminal.
• Most of the sporidia conjugate while attached
with basidium and formed Y shaped dikaryotic
hyphae.

25. Paddy- Bunt or Kernel Smut or black smut -
Tilletia barclayana (Syn: Neovassia horrida /
T. horrida)
Minute black pustules or
streaks are formed on the
grains which burst open at
the time of ripening.
The grains may be partially
or entirely replaced by the
fungal spores.

27. Wheat stem rust pathogen?
a. Puccinia graminis tritici
b. Puccinia striiformis
C. Puccinia recondita

28. Alternate host for wheat stem rust
pathogen?
A. Thalictrum
B. Barberry
C. Isopyrum

29. In case of wheat leaf rust or brown rust, completion of
spermagonia and aceia will takesplace in which crops
A. Thalictrum
B. Barberry
C. Isopyrum
D. A +C

30. Five stages of life cycle of rust
pathogen?

31. Autoceious rust?

32. Heteroceious rust?

33. Macrocyclic rust?
Microcyclic rust?