2. 1-Loose smut of wheat
Symptoms:
o All grain in spikes also be damage and infected
oSymptoms appear in maturity
oAll grains are converted into black powdery masses
oHard covering of grain is converted into very thin papery membrane
oStarching part of grain convert into black masses
oTrillion of spores produced in one spike
3. Causal organism:
Ustilago Tritici
Disease cycle:
o Fungus entirely seed borne.
oPrimary infection is the source of first infection by infected
seed and debris
oSecondary infection is the result of primary infection and the
asexual spores are produced and spread by wind.
6. 2-Coversmut of wheat
Symptoms:
oPericarp remain intact
oGrain converted into black powdery masses
oAll grain in spikes are not effected only few grains effected and convert into
black powdery masses
oHard, thin and black
oThe effected grain large in size than healthy grain
8. 3-Ergot of rye
Symptoms:
ot he ovary of cereal and grass plants. no other part of the plant is infected.
o The infected ovary is replaced by a purplish black sclerotium, commonly
ref erred t o as an ergot
o Size of the sclerotium is host plant dependent .
oThey are generally 1 t o 5 times larger than the host seed
o the largest ergots (15 cm, 0. 52 in) are found in large seeded plants such as
cereal rye
11.
4- Karnal Bunt of wheat
Introduction:
First time reported from India in 1931 Karnal district of India and in
Pakistan it’s reported in 1952 by the shipment of seed from India and
spread throughout the Punjab. The incidence is 30% from Gujrat and
Sargodha and also reported from the dry areas of Punjab i: e Multan and
Rahim yar khan.
Symptoms:
Symptoms are not prominent during early growth stages of plants. They
appear at the time of heading when more green ears are emerged. Few
grain irregularly effected in the ear converted into black powdery mass
enclosed by the pericarp. Not all the grains in a stool carry the disease and
even in the same ear only few grains are smutted. Since the embryo is not
always damaged such partially affected grains can germinate and even
produce a healthy plants
12.
13. casual organism:
Disease cycle:
•Fungus survive in the soil as teliospores and remains viable for years. At the time of
harvesting and threshing the teliospores dispersed and cause contamination. By the
sowing of infected seeds the contaminated seedlings produced than the teliospores
present in the soil germinate and produce single spore which cause the infection.
Neovossia indica
15. Management:
•Resistance verities
•Crop rotation with fodder crops
5- Downy mildew of maize
This disease is reported from India Pakistan and other parts of the world
casual organism:
Sclerospora sorghai,
16. Symptoms:
•Sorghai produce white streaks narrow long along the entire length of the leave. When the
intensity of the disease increases these stripes coalesce and form whitish yellow patches. In
some cases as a result of secondary infection the streaks are short and narrow not on entire
length. The number of stripes coalesce and margin loss to form patches. The downy growth
of fungus appears on both sides of leaves and lateral stages. There is browning of tissue,
Pickering of young leaves also noticed. Wearing cholorotic stripes. Necrosis and cholorisis at
lateral growth not on early growth. The major damage of downy mildew is complete loss of
the plant in early growth stages. Varying degree of number of grains losses during formation
of cobs with varying infection.
•
•Disease cycle:
•Oospores survive in the soil and remain in plant debris. It’s a soil borne fungus. It’s viable
when next season and produce unicellular conidia spores and cause infection and then
secondary infection is due to production of conidiophores and in one growing season they
form several successive generations. . The loss of viability at temperature 250C and 90%
relative humidity. Germination is essential for the formation of conidia and moisture and
night hours are important
•
17. Management:
Planting of resistance verities. Destruction of alternate host and other crops.
Use of fungicides like M-45 after 10 days sowing of crops with 7 days interval
is recommended. It can be controlled 100% with seed treatment with Ridomil
MZ75 (wet able powder)@4g/kg of seed.
6- Powdery Mildew of Cereals
The symptoms of this disease is very much alike in all type of cereals. The
fungus growth appears on the upper surface of the leaf. The fungus develops
numerous superficial colonies. The mycelium forms flocculent growth at first
white when conidia are formed the color will change into the grey to reddish
brown when cleistothecia are produce. Infected plants remains stunted due to
reduction in size and number of leaves.
Symptoms:
18. casual organism:
Blumeria graminis
Disease cycle:
The fungus is soil borne in the form of cleistothecia (it can survive in 13 years
at low temperature. The ascospores best germinate at 16-200C but the
optimum temperature for conidial growth is 150C. Cultivation of mix verities
delay and reduce the chance of powdery mildew
Management:
Treatment of crops stubble is recommended. Use of systematic fungicides like
vitavex but use triazole fungicides. Payten and baliton @0.1-0.2% for 100%
control
19. 7- RATOON STUNTING OF SUGARCANE
Symptoms:
•Diseased stool (single plant) stunted growth, reduce tillering and internodel
length is reduce. Stunting of canes with yellow leaves. These symptoms may
be due to nutritional deficiencies or may be lack of and may be due to poor
growth.
20. casual organism:
Clavibacter xyli subsp. Xyli
Management:
Diseased free sets should be sow.
Selection of seed from commercial crop.
Dipping the sets in hot water at 500C for 2 hours and pre-soaking.
21. 8- Aspergillus boll rot of cotton
Symptoms:
The fungal invade the cotton fiber as the result of colonization. It weaken the
fiber and cause the discoloration called as yellow strain. Fungus penetrate in
the seed coat and colonize the meal portion of the seed. The production of
aflatoxins starts in the meal portion of the seed and not in the lint and fiber.
Aspergillus fulvous
Disease cycle:
Fungus colonize the dead organic matter and produce large number of spores
and entry point for fungus into the ball is exit hole of larva of pink boll worm.
casual organism:
22. Management:
Cultural practices i: e discourage the excessive vegetative growth and
moderate use of water and nitrogen.
9- Smut of pearl millet
Symptoms:
Infection is visible of scattered grains. The infected grains may be single or in
the form of clusters and it usually confined in one side of the ear. Smut sori
are pear or oval shaped. The top of the sorus is bluntly rounded to conical in
shape. The smut grains always double then normal in size. In the beginning
the color of the grains is dark green to chocolate brown and later on become
dark black on maturity. The color is due to membrane covering the sorus, the
enclosed spore mass being always black.
23. Disease cycle:
The pathogen is soil borne. The primary inoculum consist of spores balls that
have fallen on the ground. They germinate at the time of ear formation in
next crop season. On germination they give rise to sporidia which are carried
by wind. Secondary infection of late sown crops also occurred by the spores
formed in the same season.
Management:
As the pathogen survive in the soil and the inoculum from soil is air-borne,
control of the disease is difficult. So removal of smutted ears, clean seed, hot
weather deep ploughing, field sanitation, crop rotation and use of resistant
varieties
casual organism:
Moesziomyces bullatus
Management:
24. Management:
As the pathogen survive in the soil and the inoculums from soil is air-borne,
control of the disease is difficult. So removal of smutted ears, clean seed, hot
weather deep ploughing, field sanitation, crop rotation and use of resistant
varieties.
10- Stinking Smut or Common Smut or Hill Bunt of
Wheat
Symptoms:
Infected plants remain stunted about the half of the height of normal plant.
It’s a systematic disease it starts from the seedlings. The symptoms appear at
the time of heading. The smutted ears are darker green than the normal and
remain green longer. At the milk stage of grain if punch the grain with thumb
a soft black pasty mass id yield. At the time of maturity this black mass
change into oily powdery like mass. The presence of stinking can be detected
by the found of the presence of a volatile compound tri methyl amine
25. Disease cycle:
Inoculum is seed and soil borne. Spores are easily disseminated during
threshing and cause infection after 10 years. After passage into the
intersnnnjtomal track of the cattle and sheep. Moisture and temperature,
host variety, spore load, depth of sowing all these factors affect the
infection. The spores usually germinate at 0-40C.
Management:
Crop rotation
Treatment of seed with 20% copper sulphate formalin 0.5kg in 200liters of
water.
26. 11- BACTERIAL LEAF BLIGHT OF RICE
Symptoms:
Symptoms of BLB is vary with stage of infection and prevailing weather
conditions. There are two types of phases which involve in the BLB of
rice.
Leaf blight phase is most commonly seen.it is characterized by Linear
yellow to straw color stripes with wavy margins generally on both
edges of the leaves rarely on one edge. These stripes usually starts
from tip and moves downward .the leaf tip become dry and twisted.in
some cases the linear stripes may develop on the lamina on the midrib
with or with marginal stripes. In dry weather drops of bacterial ooze
which dry into yellowish beads can be seen on the leaf surface. These
drops are washed by the rains. The glumes of seed also get infected
but symptoms
are not well defined. The blight phase usually appear after 4-6 weeks
of transplanting
27. casual organism:
Xanthomonas oryzae PV. Oryzae
Disease cycle:
: There can be several modes of perpetuation of the bacterium from one
season to other season. It survives during off season in the seeds, weeds host
and infected rice straw and stubble. The bacteria survive in the soil only for
short period of time. In pond water it has been found to remain viable for 15-
18 days. Diseased wild rice growing ponds may provide primary inoculum. The
pathogen and its phage (virus) survive longer at 15-200C than at 30-450C. The
BLB bacteria may present in 54% seeds and may survive there for 120-180
days.
Management:
Healthy certified seed should be used
Proper Field sanitation
Deep ploughing and burning of plant debris
28. 12- Bacterial ear rot, Tundo, ear cockle of
wheat
Symptoms:
The first symptom appear as a wrinkling of lower leaf and twisting of central
leaf. Bright yellow sticky slimy exuded enveloping the entire ear. During
summer the color of exudate become dry and dark yellow in color and this
cause the distortion of plant pars. The galls are Produce in the seed that’s
why the name as cockle of wheat. The symptoms appears only at the time of
maturity.
casual organism:
Rathayibacter tritici previously known as Clavibacter tritici
29. Disease cycle:
Both are necessary for infection. The bacteria survives in infected seed galls.
Next year when these galls are sow transmit the disease. The nematode
survive in the soil and mechanically enter into the plant and when plant
become mature it cause infection so it cause the rooting of ears. Up to 50%
symptoms shows presence of bacteria
Management:
Sowing of galls free seed. Galls can be remove by dipping the seed into brine
solution @ 25Kg of salt into 125 liters of water. Collect the galls from the
solution and then sow. hot water treatment resoaking at room temperature
for 24 hours next day dip in the water temperature of 54-560C for 10-12
minutes. Soil treatment with carbofuran to control the nematode and also
prevent the infection from bacteria. Proper field sanitation
30. 13-Ascochyta blight of chick pea
Symptoms:
Symptoms almost appear on all Ariel parts. Circular spots on
the leaves and pods of 3-4 cm long. Elongated spots on petiole and stem and
these spots surrounded by the brownish red margins. In severe attack of the
disease the spots may coalesce and cause entire browning of affected leave.
Later on these leaves become scotched these Circular lesion occupied by
black dots. These black dots are the fruiting body of fungi pycindia. These
pycindia are appear in a circular fashion and these pycindia are arranged in
concentric circles. The lesions will also appear on stem and gram. . In dry
weather the disease spread restricted light shower the disease spread rapidly.
The perfect stage of pathogen have been correlated with part of world.
Causal organism:
Ascochyta rabiei
31.
32. Management:
Removal and destruction of infected plant
Intercropping of chickpea with cereals
Control with agralol, copper sulphate, thiaram, roomy is effected for the control
the disease.
Use of resistance verities
14- Cotton leaf curl virus
Causal organism:
Disease causing virus belongs to Gemini group.
Symptoms:
Thickening of small veins.
Thickening of large veins.
Enation (leaf like structure) on the underside of the leaves
34. 15-Red stripe and top rot of sugar cane
Symptoms:
The disease first appear as a water soaked elongated streaks
which soon become cholorotic and carry long, uniformly dark red stripes than
these stripes coalesce to form large bands. The lower half of the leaf is more
affected than the tip. The stripes occur mostly on the young and middle aged
leaves rather than oldest. Whitish flakes of dried bacterial ooze may be seen
on the lower surface of the leaves.
The casual organism:
Pseudomonas rubrilineans and another name is Acidovorax avenge subsp.
Avenae
Disease cycle:
The bacterium is not well survive in soil and plant debris.
It can infect rice, sorghum, pearl millet etc.
35. These host may serve as agents for carry over the bacterium from season to
season.
Infection starts through wounds and stomata. The bacterium is confined to
young tissues of the host. It rapidly multiplies in the parenchymatous tissues
and moves to vascular bundles.
Management:
Once the disease sets in it’s very difficult to manage. Use of resistant
cultivars is the best method to the disease in areas where its occurrence is
common.
16-Bacterial leaf strikes of rice
Symptoms:
It’s a foliar disease. The first sign of the disease is the
appearance of fine, water soaked to translucent inter-venial streaks which
may be as long as 1 to 10 cm. these strikes are restricted by the veins and
soon turn yellow and orange brown. Minute yellow beads of bacterial
exudates are abundant on the streaks. Eventually the leaves may be
completely blighted. In many susceptible verities streaks are surrounded by
yellow halo.
36. The casual organism:
Xanthomonas oryzae PV. Oryzicola
Disease cycle:
The pathogen can in infected seed from one season to other season but not in the
crop debris in soil or through weeds. The bacteria hibernate under the glumes in
mature seed. 2-3 continuous days with high humidity 83-93% or dew during
morning hours are necessary for infection. Favorable temperature is 26-310C.
17-Wilt of sugarcane
Symptoms:
The earliest symptoms of the disease is stunting. This is noticed when the
plants are half grown. The most striking symptoms is the striking symptoms is
the yellowing or withering of the top when the crop is getting ready for
harvest , followed by rapid drying of canes. The canes becomes light and
hallow. When the canes are split open in the early stage of disease
development, the tissues particularly of the lowest internode, have a brick
red color with individual vascular strands a dark red.
37. Cereal rust
a) Black or stem rust of wheat.
b)Yellow or stripe rust of wheat.
c)Brown or leaf rust of wheat
18-Black or stem rust of wheat
Symptoms.
The rusty pustules on the upper surface of leaf, stalk and leaf sheath. These
brown pustules burst release the brown powdery masses oral surface telia
later on developed in same sorus. The rust fungus effects the physiology of
wheat plant. Transpiration increase but translocation of nutrient especially
carbohydrates related respiration increase at faster rate. So, this increase
usually reflected in the form of symptoms.
Causal organism: Puccinia graminis tritici.
38. 19-Stripe rust of wheat or yellow rust
Symptoms:
This disease appear earlier than black stem rust of wheat before the grains
formation. In mild attack uredia appear on leave but in severe attack the
pustules also developed on leaves sheath, stalk and glumes. The green color
of leaf blade faded in the form of streaks which are usually consist of
urediospores of the fungi. So each row consist of series of oval lemon yellow
pustule. Pustules arranged end to end like the stitching machine. In severe
attack the serial arrangement lost and large patches covered with crowded
pustules developed.
Causal organism:
Puccinia striiformis
39. 20-Leaf or brown rust of wheat
Causal organism:
Puccinia recondita
Symptoms:
The uredia develop on leave sheath and stalk. These uredia burst on the
upper surface of the leaves as bright orange color points. It appear earlier
than stripe rust. They are gathered in small clusters, regular scattered on
leave surface. They are bigger in size than the uredia of yellow rust only
difference between yellow and leave rust is the leaf rust uredia burst earlier
exposing the powdery masses. The sometime teliospore may not develop but
if they develop, they are similar to yellow rust. Like small, oval, dull black
and covered by the epidermis. Excessive transpiration rate the plant take
much more time to produce mature ears. Heavy rusting of foliage result in
poorly develop root system Poor quality and quantity of grain and reduce the
yield of wheat straw.
40. Dispersal of Urediospore
. The dissemination of Urediospore in little initial inoculum increase the
varies infection center being continuous by disseminated by wind so, it
increase the infection center subsequently because of long distance dispersal
of Urediospore, it’s difficult to know whether the primarily inoculum has been
brought from nearby place or by hill area. The dispersal distance of uredia
spore 38km/h when wind will be about 1760km/h.
Epidemiology:
Humidity and temperature plays an important role. Germination of
Urediospore effected by temperature the optimum temperature is 240C and
very low temperature is not favorable for Urediospore germination. If wetness
is prevail for long time than usually 6 hours at 60-65% humidity is required for
pustules production, so for the germination of Urediospore in free water or
dew deposit on leaf surface for two hours is essential for all three types of
rust
41. Management:
. Sowing of two different crops at sometimes there is only hypothesis may
minimize the primary inoculum. Nitrogen increase the incidence of rust
disease whereas potash decrease, so balance application.
Use of resistant varieties.
. Use of systematic fungicide.
. Soil and seed treatment with fungicide.
