This is small topic named:MODE OF ENTRY AND ESTABLISHMENT OF FUNGUS INTO SEEDS. which is taken from the course PRINCIPLES OF INTEGRATED PLANT DISEASE MANAGEMENT.

1. PRINCIPLES OF INTEGRATED PLANT
DISEASE MANAGEMENT
(1+1)

2. MODE OF ENTRY AND
ESTABLISHMENT OF FUNGUS INTO
SEEDS
BY: B.SUBHASH

3. FUNGUS
• A fungus (plural: fungi or funguses) is any
member of the group of eukaryotic organisms
that includes microorganisms such as yeasts and
molds, as well as the more familiar mushrooms.
• These organisms are classified as a kingdom,
which is separate from the other eukaryotic life
kingdoms of plants and animals.

4.  Pathology is the science deals with micro-organism infecting
seeds.
 Seeds are attacked by various fungi, bacteria and virus.
 Seeds are attacked in various stages,
 Seeds of the mother plant infected by the pathogen, may
also get infected by the same.
 During processing.
 At the time of transportation.
 During storage
SEED BORNE FUNGUS

5. SEED BORNE FUNGUS (cont…)
• Seed borne pathogens result in seed rots,
seedling decay, pre and post emergence
mortalities, abnormalities, discoloration,
reduced seed size and shrivelledness of seeds
• The seed borne pathogens not only affect the
market value but also nutritive value of the
products

6. MODE OF ENTRY OF FUNGUS INTO
SEEDS
•Most phytopathogenic fungi belong to the Ascomycetes and
the Basidiomycetes.
• The fungi reproduce both sexually and asexually via the
production of spores and other structures.
•Spores may be spread long distances by air or water, or they may
be soil borne.
•Many soil inhabiting fungi are capable of living saprotrophically,
carrying out the part of their life cycle in the soil.
• These are facultative saprotrophs.
•Fungal diseases may be controlled through the use
of fungicides and other agriculture practices.

7. MODE OF ENTRY OF FUNGUS INTO
SEEDS

8. Classification of establishment of
fungus into seeds
INTERNAL SEED BORNE FUNGUS
• Pathogenic fungi infect
the internal tissue of seeds,
destroying the embryo and
endosperm or gametophyte
tissue.
• Examples include L.
theobromae, which destroys
slash pine seeds in the
Southern parts of India.
EXTERNAL SEED BORNE FUNGUS
• During harvest the smutted
parts of the cereal plant are
broken apart spreading smut
spores and contaminating
healthy seed, machinery
and soil.
• Externally seed
borne smut diseases include
common bunt and flag smut
of wheat, covered smut of
barley and covered smut and
loose smut of oats.

10. LOOSE SMUT OF WHEAT
Ustilago nuda tritici
Ustilago nuda f.sp. tritici is a basidiomyceteous fungus that
affects wheat. It is also known as loose wheat smut, or
loose smut of wheat.
• Seed-borne fungal mycelium establishes itself in the embryo
of the seed at flowering.
• As the seed matures, the mycelium becomes dormant.
• When infected seed germinates the following spring, the
mycelium begins to grow and penetrates the growing point.

11. SYMPTOMS
• Generally, diseased plants are indistinguishable from the healthy
plants before heading but diseased plants produce heads earlier
than healthy plants.
• Terminal symptom in all the varieties is the production of black
powder in place of wheat grains in the ears. Almost every ear of
the diseased plant is converted into black powder.
• The black powder is a mass of olive-green microscopic spores of
the smut fungus.
• When spores are blown to flowers of healthy plants, they
germinate on the female organ, stigma and lead to infection of
the developing seed.
• The smut fungus thus reaches in the mature grain and remains
dormant there until germination of the grain.

12. LIFE CYCLE

13. MANAGENENT OF LOOSE SMUT OF
WHEAT
• Treat the seed with Vitavax @ 2g/kg seed before sowing.
• Burry the infected ear heads in the soil, so that secondary
spread is avoided.
• Seeds are typically treated with a systemic fungicide to kill
any fungus that may be inside. Since the fungus grows up
with the plant .
• The most common type of systemic fungicides used for loose
smut are from the Carboxin group of chemicals.

14. LOOSE SMUT OF BARLEY
• Loose smut of barley is caused by Ustilago nuda.
• It is a disease that can destroy a large proportion of
a barley crop.
• Loose smut replaces grain heads with smut, or masses
of spores which infect the open flowers of healthy plants
and grow into the seed, without showing any symptoms.
• Seeds appear healthy and only when they reach maturity
the following season is it clear that they were infected.

15. HOST AND SYMPTOMS
• The major symptom of loose smut is the "smutted" grain
heads, which contain masses of black or brown spores
where the grain would normally be.
• The spores completely replace the grain head so that there is
no grain to be harvested on infected plants.
• It may be possible to identify infected plants in the field
before they reach the flowering stage by looking for plants
which are taller and more mature than the rest of the field.
• The fungus causes infected plants to grow slightly taller and
mature slightly sooner than the uninfected plants in the
field.

17. MANAGEMENT OF LOOSE SMUT OF
BARLEY
Use clean seed:
•Apply systemic fungicide treatment of seeds. Contact fungicides
are not effective
•Apply heat treatment, but viability and germination rate should
be checked and compensated for
Use resistant cultivars
•Perform field checks for infected seed and prevent the use of seeds
from infected fields for further cropping
•Prevent plant diseases by optimizing plant potential and crop
resilience.
•Treat the seed with Vitavax @ 2g/kg seed before sowing.

18. Alternaria leaf spot
Scientific name: Alternaria
alternata
Higher classification: Alternaria
Class: Dothideomycetes
Division: Ascomycota
Kingdom: Fungi
•Alternaria alternata is a fungus which has been recorded
causing leaf spot and other diseases on over 380 host
species of plant.
•It is an opportunistic pathogen on numerous hosts
causing leaf spots, rots and blights on many plant parts.
•It can also cause upper respiratory tract infections
and asthma in humans with compromised immunity.

19. HOST AND SYMPTOMS
•Alternaria leaf spot is caused by the fungus Alternaria dauci.
•Infection can be initiated by seedborne or windborne spores
(conidia), which germinate in the presence of free moisture and
penetrate leaves through wounds or natural openings.
HOST
SYMPTOMS
•Cracks appearing in leaf spot
•The two species of Alternaria occur
commonly, causing the characteristic leaf
spots with concentric rings.
•The spots are mostly irregular, 4-8 mm
in diameter and may coalesce to cover
large areas of the leaf blade.
•Severely affected leaves may drop off.

20. LIFE CYCLE

21. Management
•Spraying 1 per cent Bordeaux mixture or 2 g Copper oxychloride or 2.5
g Zineb per litre of water effectively controls leaf spots.

23. FLAG SMUT OF WHEAT
•Flag smut of wheat (Urocystis tritici) differs from other cereal
smut diseases by exhibiting symptoms in the leaves rather than
the heads.
• Affected plants are often stunted and infected leaves may be
curled and distorted.
•Initially, the spore masses are invisible under the leaf surface,
but between stem elongation and heading, they break through
the surface as distinct, long, raised streaks of sooty spores on
leaves and leaf sheaths.

25. Disease Cycle
•During harvest the black spores are released from the plant
contaminating seed and soil.
•Typically spores survive in soil for 3 years, but can survive for up to 7
years.
•Soil or seed borne spores infect the new wheat plant before
emergence. Infection is favoured by early sowing into relatively dry
and warm soils.
•Optimal temperature for infection is 20°C, but infection may occur at
as low as 5°C and as high as 28°C.
•The fungus grows inter and intra cellularly between vascular bundles
of the leaf tissue and other effected plant parts.

26. MANAGEMENT PRACTICES
Preventive methods
•Use of disease-free seeds that are selected from healthy
crop.
•Seed treatment with carbendazim 2.0g/kg of seeds.
•Control insect pests.
•Split application of nitrogen is recommended.
•Removal and proper disposal of infected plant debris.
Cultural methods
•Among the cultural control, destruction of straw and stubble
from infected plants is recommended to reduce the disease.
•Use varieties that are found to be resistant or tolerant against
the disease in India.
•Avoid field activities when the plants are wet.
•Early planted crop has less smut balls than the late planted
crop.

27. COVER SMUT OF BARLEY
•Covered smut of barley is caused by the fungus Ustilago hordei.
•The disease is found worldwide and it is more extensively
distributed than either loose smut or false loose smut

28. SYMPTOMS
•The individual grains are replaced by smut sori.
•Sori are covered with creamy skin.
•Sori can be localized at a particular part of the head, or can occur over
the entire inflorescence.
•Ratoon crops exhibit a higher disease incidence.

29. LIFE CYCLE

30. MANAGEMENT
•Seed treatment with Carboxin
(Vitavax) @ 2g/kg or Captan/Thiram
4g/kg of seed.
•Collect smutted earheads in cloth
bags and destruct by dipping in boiling
water.
•Avoid rationing

31. BUNT OF WHEAT
•Tilletia caries (synonymous with Tilletia tritici) is
a basidiomycete that causes common bunt of wheat.
•The common names of this disease are stinking bunt of wheat
and stinking smut of wheat.
• This pathogen infects wheat, rye, and various other grasses.
• Tilletia caries is economically and agriculturally important
because it reduces both the wheat yield and grain quality.

33. LIFE CYCLE