This document discusses loose smut and flag smut of wheat. Loose smut is caused by the fungus Ustilago nuda tritici. It is seed-borne and causes entire wheat heads to be converted into black spore masses, reducing yields by 2-3%. Flag smut is caused by Urocystis tritici and produces grey-black lesions on leaves and stems. Both diseases are favored by humid conditions. Management strategies include seed treatment, growing resistant varieties, and crop rotation to break disease cycles.

1. STUDENT COURSE TEACHER
GAYATHRI.D Dr. S. PARTHASARATHY
ID. No. 2016021010 Assistant Professor (Plant Pathology).
COLLEGE OF AGRICULTURAL TECHNOLOGY
(Affiliated to Tamil Nadu Agricultural University, Coimbatore)
(Accredited to Indian Council of Agriculturral Research,New Delhi)
Kullapuram, Via Vaigai dam, Theni-625 562
LOOSE SMUT AND FLAG SMUT OF WHEAT

2. LOOSE SMUT
SIGNIFICANCE
• Loose smut caused by Ustilago nuda tritici. It is
one of the major diseases on wheat. There was
loose smut epidemic during 1970-75 in Punjab,
Haryana and Western U.P.
• In Sonalika, the incidence was 5 to 6%.
• Incidence is more in North than in southern parts
of India.
• Country wide loss is about 2-3% in total yield.

3. DISTRIBUTION
• All wheat growing regions of India.
• Particularly in the Punjab, Uttar Pradesh and certain
districts of Madhya Pradesh.

4. SYMPTOMS
• The destructive nature of the disease lines in the fact
that every head of the affected plants maybe
converted into a black mass of spores and no grains
are formed.
• Significant reduction in height and number of tillers.
• Symptoms appears after ear emergence.

5. SYMPTOMS
• Except awns all parts of ear converted into smut
spore.
• Black powder in ear –covered by silvery membrane.
• Group of smut spore called “sorus”.
• High respiration.
• Low dry weight of plant.

6. LOOSE SMUT OF WHEAT
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7. LOOSE SMUT OF WHEAT
cropgenebank.sgrp.cgiar.org

8. Kingdom Fungi
Phylum Basidiomycota
Sub phylum Ustilaginomycotina
Class Ustilaginomycetes
Order Ustilaginales
Family Ustilaginaceae
Genus Ustilago
Species U.tritici (Pers.)
SYSTEMIC POSITION

9. PATHOGEN -CHARACTERS
• Loose smut caused by Ustilago nuda tritici. It is a
internally seed borne fungal disease.
• It cause systemic infection.
• The chlamydospores of the fungus are pale, olive
brown, spherical to oval in shape, about 5-9 micro
diameter and are adorned with minute echinulations
on the wall.

10. PATHOGEN CHARACTERS
• They germinate readily in water, each spore
producing one four celled germ tube(promycelium).
• The promycelial cells fuse and give rise to the germ
tubes that enter the ovary through the stigma and
become established in the embryo, remaining
dormant until seed germination.
• Its presence is revealed only when the plant matures
and a smutted ear emerges.

11. MYCELIUM CHARACTERS
• The Primary mycelium consists of hyaline, slender,
septate hyphae with a single haploid nucleus in each
cell. (Monokaryotic or haplo mycelium).
• The Secondary mycelium consist of hyphae with two
haploid nuclei in each cell. (Dikaryotic hyphae).

12. MYCELIUM OF LOOSE SMUT
www.biologydiscussion.com

13. DISEASE CYCLE
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14. EPIDEMOLOGY
MODE OF SPREAD
PRIMARY SPREAD
(Dormant mycelium)
•
• It is internally and externally seed borne and is
systemic. The fungus is carried over in the seed as
dormant mycelium. When the planted seed
germinates the mycelium becomes active.
• It grows along with the plant and when the panicle is
produced the mycelium reaches the ovaries and
transforms the ovaries into a mass of black smut
spores.
• m the infected heads land on the later emerging florets and
infect the frequent rain showers, high humidity and temperature. The disease is
internally seed borne, where pathogen infects the embryo in the seed.

15. SECONDARY SPREAD
(Teliospores)
• Secondary spread occurs through wind borne smut
spores. The sporidia infect the healthy flowers. The
mycelium enters the ovary and remains in the seed as
dormant mycelium.

16. FAVOURABLE CONDITIONS
• Cold climate (16 -22°C).
• Humid weather - 60-85%.

17. MANAGEMENT
• Treat the seed with Carboxin (Vitavax) @ 2g/kg seed
before sowing.
• Grow resistant varieties like Sonalika, Kalyan 227,
PV18, WG307, NP13 and C302.
• Burry the infected ear heads in the soil, so that
secondary spread is avoided.
• Spraying of fungicides like Carboxin (Vitavax)
0.125% or Tebuconazole (Folicur) 0.2%.

18. • Hot water treatment (Jenson, 1886): Soak the seeds in
water @ 26-30°C for 5 hours to induce dormant
mycelium to grow. Then immerse the seeds in hot
water a @ 54°C (129°F) for 10mins to kill the
mycelium.
• Solar treatment (Luthra and Sattar, 1954 in Punjab):
Soak the seeds in cold water for 4 hours from 6AM to
10AM in the forenoon on a bright sunny day
followed by spreading and drying of seeds on brick
floor in bright sun (44°C) for 4 hours from 10AM to
5PM in the afternoon.

19. FLAG SMUT
SIGNIFICANCE
• Flag smut caused by Urocystis tritici(U.agropyri) was
an important disease in Victoria.
• Flag or stem or stripes smut, of wheat was 1st
observed in South Australia in 1868.
• Typical loss range in Australia is 5-20%.
• In India the losses due to flag smut is 3-5%

20. DISTRIBUTION
• World: Japan, South East Asian countries, India,
Pakistan, Middle East countries, Europe, South Africa
and the U.S.A.
• India: Haryana, Madhya Pradesh , Delhi, Rajasthan
and Himachal Pradesh.

21. SYMPTOMS
• The early symptoms include “Leprous” spots.
• The symptoms can be seen on stem, culm and leaves
from late seedling stage to maturity.
• The seedling infection leads to twisting and drooping
of leaves followed by withering.
• Grey to greyish black sori occurs on leaf blade and
sheath.
• The sorus contains black powdery mass of
spores.

22. Flag smut of wheat
www.alamy.com

23. SYSTEMIC POSITION
Kingdom Fungi
Phylum Basidiomycota
Class Ustilagomycetes
Order Urocystidales
Family Urocystidiaceae
Genus Urocystis
Species Agropyri (Preuss) 1867

24. PATHOGEN -CHARACTERS
• The pathogen is seed borne as well as soil borne
disease.
• Aggregated spore balls, consisting 1-6 bright globose,
brown smooth walled spores.
• surrounded by a layer of flat sterile cells.
• Basidiospore germinates to produce primary
mycelium.

25. Spore balls
www.discoverlife.org

26. DISEASE CYCLE
en.wikipedia.org

27. EPIDEMOLOGY
MODE OF SPREAD
• The pathogen is seed borne as well as soil
borne disease.
• Basidiospore germinates to produce primary
mycelium.
• Primary infection occurs by sowing infected
seeds or by resting spores present in soil.

28. FAVOURABLE CONDITIONS
• Temperature of 18-24°C.
• Relative humidity 65% and above.

29. MANAGEMENT
• Treat the seeds with brine solution.
• Use cleaned seeds.
• Avoid seeds from infected area.
• Fallow 3 years crop rotation in disease sick plots.
Rotation helps to break the cycle of disease.
• Roughing and burning of infected plants.

30. MANAGEMENT
• Treat the seeds with carboxin(Vitavax) or
tebuconazole(Folicur) or triadimefon(Bayleton) @ 2g
/kg.
• Grow resistant varieties like Pusa 44 and WG 377.
• Dry seed-dressing with non-systemics such as copper
carbonate and systemics such as carboxin,
oxycarboxin (Plantvax) and pyracarbolid have also
been used .

31. REFERENCES
• Rangaswami, G and Mahadevan, A.2016. Diseases
of Crop Plants in India. Rekha Printers Private
Limited, New Delhi.
• Singh, R. S., 2018. Plant Diseases. Scientific
International (Pvt.) Ltd, New Delhi.