This document discusses several major diseases that affect wheat crops. It outlines 5 key diseases: rusts (stem, leaf, and stripe rust), loose smut, Karnal bunt, and Alternaria blight. Rusts are fungal diseases that can cause losses up to 70% and are a major threat to global wheat supply. Loose smut infects wheat heads, replacing grains with spores. Karnal bunt causes a fishy smell in infected grains. Management of these diseases requires resistant varieties, fungicide application, crop rotation, and control of alternate hosts.

1. Crop Disease and their
management
1. WHEAT DISEASE

2. Significance
 Wheat is the sixth most important crop.
 Grown yearly on 220.4 million hectares.
 Possess net worth more than 22 billion dollars.
 World trade in wheat is greater than for all other crops combined.
 Losses up to 60 to 70%.
 Major disease of wheat and, therefore a potential threat to the world food supply.
 More than 5 billion dollars are lost due to cereal rust each year.
 Wheat black stem rust was a serious problem in ancient Greece and Rome.

3. Diseases of Wheat plant
(Triticum aestivum L.)
 Rusts ( Black or stem rust, Brown or leaf rust,
Yellow or stripe rust)
 Loose smut,
 Kernel bunt,
 Powdering mildew,
 Alternaria blight,

4. 1. Rusts
 Three forms of rusts can affect wheat
 (all are fungal forms of family pucciniaceae)
 Puccinia is an obligate (need two host) parasite.
 It is a heteroecious parasite.
 It’s life cycle completes on Wheat and Barberry.
 Wheat is a primary host. Barberry is a secondary or alternate host.

5. a) Black Or Stem Rust Of Wheat
 Causal organism: - Puccinia graminis Tritici
 1767 - Italian scientist Fontana and Tozzetti independently provided
first detailed descriptions of stem rust fungus in wheat.
 1797 - Persoon named it Puccinia graminis.
 1865 – Anton de Bary first demonstratedthe heteroecious lifecycle of a
rust fungus withPuccinia graminis.
 The disease is present almost everywhere, where wheat crop is grown.

6. Wheat stem rust infection type

7. Symptoms
 Do not produce symptoms until 7-15 days from infection.
 Elongated to irregular shaped pustules (uredinia) of brick- red urediniospores
break through the epidermis and develop on the upper leaf surfaces, leaf
sheaths, glumes and awns.
 The stem become dry and cracked.
 The plant produces less or no grains.

9. Disease Cycle

10. Favourable Conditions
 Warm ‐humid weather conditions with intermittent rains.
 Hot days 25 ‐ 30º C and mild nights (15 ‐ 20º C)
 Leaf wetness from rain or dew
 It appears in the month of March in Northern India, In
Southern and Peninsular India it appears very early in the 4th
week of November.
 Infections occur through stomata.

11. Management
 Adjustment of sowing dates.
 Growing short and long duration crops.
 Applications of balanced fertilizers to thecrop.
 Eradication of barberry trees around the wheat field
 rust resistant varieties of wheat UP 215, HD 2501, HD 238, NP 822,
NP 823 and NP 825
 Lerma Rojo, Safed Lerma, Choti Lerma and Sonalika are highly
resistant to all three rusts in thefield.
 Recommended Zineb, Maneb, Dithane Z-78 and Dithane M-45 to
control wheat rusts effectively.

12. b) Brown or leaf rust
 Causal organism: -Puccinia recondita
 HOSTS: - Wheat, barley and common barberry ( Berberis, Mahoberberis)
 The pathogen is macrocyclic rust.
 Uredospores are brown and spherical 16-28 um in diameter.

13. Wheat leaf rust infection type

14. Symptoms
 Scattered oval to circular small brown pustules (rusty-red
uredospores) containing a powdery mass of orange to
red‐orange spores develop on the upper leaf surfaces, leaf
sheaths, glumes and awns.
 The black telial pustules are usually formed on the dorsal side of
leaves
 The pustules brust early with mild displacement of the host
epidermis and deeply embedded into the host.

16. Disease Cycle

18. Favourable conditions
 Warm ‐humid weather conditions with
intermittent rains.
 Hot days 25‐30º C and mild nights (15‐20º C)
 Leaf wetness from rain or dew

19. Management
 Mix cropping and Crop rotation
 Avoid the excess use of fertilizers
 Sulphur dusting @ 35 – 40 kg/ha.
 Mancozeb @ 2 g/lit of water, dithiocarbamates and
RH-124 (1 or 2 foliar spray)

20. c. Yellow or Stripe rust
 Causal organism: -Puccinia striiformis f. sp. Tritici
 Gadd first described stripe rust of wheat in 1777.
 In 1896, Eriksson and Henning showed that stripe rust resulted from a
separate pathogen, which they named P. glumarum.
 In 1953, Hylander et al. revived the name P. striiformis.
 Losses can be 50%, but in severe situations 100% is vulnerable.
 In India, (Hills, foothills and plains of north western India and southern hills
zone (Nilgiri hills of Tamil Nadu). And In World Europe and Australia

22. Symptoms
 The first sign of stripe rust is the appearance of yellow streaks (pre-
pustules), followed by small, bright yellow, elongated uredial pustules
arranged in conspicuous rows on the leaves, leaf sheaths, glumes and
awns .
 Mature pustules will break open and release yellow-orange masses of
uredospores.
 In some varieties, long, narrow yellow stripes will develop on leaves.
 The infected tissues may become brown and dry as the plant matures or
becomes stressed.
 Severe early infection can result in plant stunting.

24. Disease Cycle

25. Favorable Conditions
 Stripe rust is most common in higher elevations and cooler climates.
 The pathogen is best sustained when night time temperatures are < 15°C.
 Stripe rust can develop on wheat at lower temperatures than other rusts.
 Optimum uredospore germination occurs at 7-15°C.
 Infection and disease development is most rapid between 10- 16° C .
 Heavy dew or intermittent rains can accelerate the spread of the disease.
 Infection tends to cease when temperatures consistently exceed 21-23° C.
 Pathogen survives in the cool temperatures of hills ( Himalayas and Nilgiris )
and the primary infection takes places by middle of January in the foot hills and
sub mountainous parts of north western India.

26. Management
 Mixed cropping and crop rotation.
 Avoid excess Nitrogenous fertilizers.
 Sulphur dusting @ 35-40 kg/ha.
 Spray Mancozeb @ 2 g/lit.
 Growing Resistant varieties.
 Lerma Rojo, Safed Lerma, Sonalika and Chotil.
 PBW343, PBW550, PBW17.

27. 2. Loose Smut
 Causal organism - Ustilago nuda tritici
 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
 Particularly in the Punjab,Uttar Pradesh and certain districts of Madhya
Pradesh.

30. 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.
 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.

33. Disease Cycle
 Infected plant emerges early.
 Infection during flowering is favored symptoms by frequent rain snow,
high humidity and temperature.
 The disease is initially seed borne, where pathogen infects the embryo in
the seed

35. Favorable Conditions
 Cold climate (16 - 22° C).
 Humid weather - 60-85%.
 Snow rain

36. 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%.

37. 3. Karnal Bunt of Wheat
 Causal organism: - Tilletia indica (Syn. Neovassia indica)
 Karnal bunt is so named because it was discovered in 1931 on wheat grown
near Karnal, India by Mitra.
 Initially, the disease was reported as Neovassia indica (Mitra) Mundkur in 1940
then it was called as Tilletia indica Mitra in 1953.
 The infected grain gives decaying fish smell due to trimethylamine.
 The disease is sometimes called partial bunt because only part of the kernel
usually is affected.

39. Symptoms
 The fungus causes a reduction in the length of ears as well as in the
number of spikelet's of bunted ears.
 Infected plants may be dwarfed
 The smell of decaying fish on grains.
 Plants ripen early than the healthy one
 The disease is not usually noticed until the grain is threshed and partially
smutted kernels are exposed.

41. MODE OF INFECTION
Primary spread of disease–The monocotyledon appeared to sporidial survival.
Secondary spread of infection and soil borne disease.

42. Disease cycle

43. FAVORABLE CONDITIONS
• High humidity favours this disease.
• Temperature ranges from (8 - 23° C)
• Frequent rainfall favours development.
• High dose of nitrogen.
• Close planting favours pathogen attack.

44. Management
CULTURAL PRACTICES:
 Grow resistant varieties such as HD 1907, L 176, HI 358, HP 743 and L 191.
 Crop rotation may help to control the pathogen, because T. indica can
survive for up to 4 years in the soil.
 The movement of farm machinery from contaminated fields may also be
restricted.
 To prevent the spread of T. indica into previously unaffected areas, the
use of disease- free seed is essential.
 Deep ploughing is done to remove spores.
 Split application of Nitrogen fertilizer reduces the incidence of the
disease.

45. • Chemical seed treatments have proved to be ineffective in killing
the teliospores of T. indica on seeds of wheat, with the exception of
mercurial compounds, which are banned in most countries.
• Bleach, in combination with heat treatment, is effective(Soaking at
35°C for 12 h was the most effective treatment).
• Carboxin + thiram and Chlorothalonil have been used as seed
treatments in the USAand Mexico.
• Foliar spray of Propiconazole was shown to be effective against
natural infection in India.
• Apply Cyproconazole @ 500 ml/ha and Bavistin @ 1000g/ha may
be recommended.

46. 4. p. m - Erysiphe
graminis tritici
2. Ustilago nauda
3. tilletia indica mitra
5. A B - ALTERNARIATRITICINA