3. INTRODUCTION
• Maize one of the major cereals
• Grown in irrigated conditions & rainfed
• Food, feed and fodder crop.
• Among cereals, maize in India
• Ranks 5th in total area,
• Fourth in total production
• Third in yield per hectare.
4. Major diseases of maize
•
•
•
•
Turcicum leaf blight,
Sorghum downy mildew,
Common rust and
Post-floweriisng stalk rots
5. Sporadic diseases are
• Mayadis leaf blight,
• Phaeosphaeria leaf spot,
• Brown spot,
• Fusasium wilt,
• Polysora rust,
• Cyst and lesion nematodes
6. Diseases and stage of crop
• Most diseases occur in late vegetative phase and
during grain formation.
Root and stalk rots cause premature plant death or
contribute to lodging and harvest losses through
weakened stalks.
Ear and storage rots further reduce the feeding
value of the grain and a few of these organisms
produce chemicals which are toxic to animals.
•
•
7. Yield loss by major diseases under experimental
conditions in susceptible cultivars of maize
Disease
Bacterial stalk rot
Loss (%)
100
Pythium stalk rot 100
Late wilt 50.9
Charcoal rot 39.5
Maydis leaf blight 30.3
Turcicum leaf blight 66.0
Common rust 32.0
Brown spot 27.0
Brown stripe downy mildew 63.0
Banded leaf and sheath blight 40.5
8. Estimation of losses due to major diseases of maize in India
Disease group Loss (%)
Seed and seeding blights 0.2
Downy mildews 2.0
Foliar diseases
(Turcicum leaf blight, Maydis leaf blight,
Phaeosphaeria leaf spot, rust, )
5.0
Stalk rots, root rots, ear rots 5.0
Sheath blights, smut, viruses and other 1.0
Total 13.2
9. Important diseases of maize, their distribution and economic importance
Sl.
Disease Pathogen
Plant parts
Extent
of
Distribution
Mode of
No. affected yield
loss
survival
1 Turcicum leaf
blight
Exserohilum
turcicum
Leaf 66% Jammu and Kashmir,
Himachal Pradesh, Sikkim,
West Bengal, Meghalaya,
Tripura, Assam, Rajasthan,
Uttar Pradesh, Bihar, Madhya
Pradash, Gujarat,
Maharashtra, Andhra Pradesh,
Karnataka, Tamil Nadu.
Soil, Plant
debris
2 Maydis leaf
blight
Drechslera
maydis
Leaf, Leaf
sheath, Ear
husk
30% Jammu and Kashmir,
Himachal Pradesh, Meghalaya,
Soil Plant Punjab, Haryana,
Rajasthan, Delhi,
Uttar Pradesh, Bihar, Madhya
Pradash, Gujarat,
Maharashtra, Andhra Pradesh,
Karnataka, Tamil Nadu.
Soil, plant
3 Common rust Puccinia
sorghi
Leaf, Leaf
sheath, Ear
husk, Tassel
32% Jammu and Kashmir, Sikkim,
West Bengal, Punjab (winter),
Haryana, Rajasthan, Delhi,
Uttar Pradesh, Bihar, Madhya
Pradash, Gujarat,
Maharashtra, Andhra Pradesh,
Karnataka, Tamil Nadu.
Uredospores
4 Phaeosphaeria
leaf spot
Phaeosphaeri
a maydis
Leaf 25% Sikkim, WB, UP, HP,
Maharashtra, Karnataka
Plant debris
11. Important diseases of maize, their distribution and economic importance
(Contd..)
Sl.
No.
Disease Pathogen Plant parts
affected
Extent
of yield Distribution Mode of
survival
loss
12 Sorghum
downy
mildew
P. sorghi Whole plant 100% Rajasthan, Gujarat,
Maharashtra, AP, Karnataka,
Tamil Nadu
Soil,
Oospores
13 Sugarcane
downy
mildew
P. sacchari While plant 100% UP, Bihar Soil,
Oospores
14 Brown spot Physoderma
maydis
Leaf and
sheath
27% JK, HP, Sikkim, West Bengal,
Karnataka Punjab, Rajasthan,
MP
Soil, Resting
spores
15 Banded leaf
and sheath
blight
Rhizoctonia
solani
sasakii
f.sp.
Leaf and
sheath
41% JK, HP, Sikkim, Punjab,
Karnataka Haryana, Rajasthan,
Delhi, UP, Bihar
Soil, debris
16 Cyst
nematode
Heterodera zeae Root Rajasthan, MP, Bihar, UP,
Karnataka
Soil
17 Pohysora rust Puccinia polysora Leaf & sheath 50% Karnataka, AP, Maharshstra Soil, plant
12. DM of Maize
• Number of downy mildew fungi.
• Crazy top
• Peronosclerospora philippinensis
• P. maydis, P. sorghi, P. sacchari
• Sclerophthora rayssiae zeae.
13. Symptoms :
•
•
•
•
•
•
•
•
•
Most of the timesymptoms are similar.
P
.sacchari Long, broad continuous yellowish chlorotic stripes
along veins.
Leaf shredding not seenbutin severely infection – later stage
shredding seen.
Evenon baseof tassel downy growth seen.
Miniature leaves on tassel. Ganga– 3 Multiple ears.
Branching of stem.
Mainly on top young leaves.
Compared to old matured lower leaves.
Secondary spread is seen yellow stripes.
16. •
•
CRAZYTOPOFCORN:
Symptoms
The most characteristic symptom is the development of
chlorotic streaks on the leaves. Plants exhibit a stunted and
bushy appearance due to shortening of the internodes. White
downy growth is seen on the lower surface of leaf. Downy
growth also occurs on bracts of green unopened male flowers in
the tassel. Small to large leaves are noticed in the tassel.
Proliferation of auxillary buds on the stalk of tassel and the cobs
iscommon(Crazy top).
DISEASECYCLE:
10infection:sporangiophoresand sporangia
20 in
fec
ti
o
n :o
o
s
p
o
r
e
s
19. Brown stripe downy mildew
(Sclerophthora rayssiae var. zeae)
•
•
SYMPTOMS
Lesions on the leaves develop as
narrow chloroticstripes,
variable in length,3-7 mm wide.
•
• These stripes extend in parallel
fashionandhavewell-defined margins
becauseof their beingvein limited.
• Stripes in advanced stages become
necrotic and present a brown burnt
appearanceto the leaves.
A fine downy growth can be seen on
the stripes.
•
20. Management
1) Resistantmaizecultivars,
HybridsGanga5, Ganga9,
Composites,Kisan,Tarun,Naveen, Sweta, Kanchan.
2)Plant maizeat leasta fortnight before the onsetof rains.Incidenceof the
diseasebecomeslessif plantingisdoneduringdry season.
3) Selectwell drained fieldsfor maize planting,
or arrangeproper drainageto drain out the excessrainwater.
4) Thediseasecanbeminimizedbysprayingthe foliagewith fungicides
suchasmetalaxyl or mancozeb (0.3%).
Firstsprayingshouldbedoneabout a month after plantingor assoonas
the diseasesymptomsare seen.
Other 3-4 spraysshouldbedoneat 10-15 daysintervals dependingon
severityof the disease.
5) Burnthe cropresidueafter the harvest.
6) Practicethree year croprotation to minimizethe initial inoculumloadin
the field.
22. Disease management
1) Plant diseaseresistant maizecultivars- Suwan.
Amongst the released hybrids, Ganga S
afed 2 least
susceptible.
2) Treatingmaizeseedwith a systemicfungicide,metalaxyl @
3 g/kg
3) Provideadequate soildrainageor avoidplanting in low, wet
spots.
4) Plantingshouldbedoneat least a fortnight before the onset
of rains.
5) Thediseasecanbeminimized byfoliar sprayingof fungicides
like mancozeb/ metalaxyl @3 kg/ha at frequent intervals.
6) Burnthe residuesafter the crop harvest.
24. 1. long elliptical grayish green or tan lesions on leaves
2.5 to 25 cm in length and 4 cm in width.
2. Lesions first appear as slightly oval, water
soaked, small spots on lower leaves and increase
in size and number
3. Progress upwards until a complete burning of
the foliage.
Under high humidity the whole leaf area becomes
necrotic and plants appear as dead.
4. Spores produced on the under surface are arranged
in concentric zones resembling a target like
pattern.
Turcicumleaf blight (Exserohilumturcicum)
symptoms
25. Disease management
1) Use of resistant cultivars
DMH-2, Prabha
2) Two or three foliar sprays with 0.25 % mancozeb or
zineb at 10-15 days intervals.
First spray soon after the disease appearance.
3)Application of urea followed by a light irrigation helps
to minimize the disease as this disease becomes
serious under poor management, i.e., under low
nitrogen and water stress.
27. •
blemishes, spots, silk-cut and
The infected seeds broken having
show
signsof softening,rotting,
Theseedlingsare thin, patchy growth,
•
post-emergence damping-off and
brownsunkenlesionon mesocotyl.
Water – soakedareasare alsoseenon
the collarregion.
Seedlings may wilt, collapse or topple
from the point of emergence.
Leaves become flaccid or begin to dry
•
•
•
partially or wholly and sometimes
external fungus growth can also be seen.
28. Disease management:
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•
1)Certified seeds.
2)Farmers seeds can be treated with thiram or bavistin @ 2.0
g/kg.
3)Good quality seed taken from disease-free healthy plants.
4)Eliminate seed lots showing streaking, pericarp injury or
those showing any kind of blemishes;
5)Avoid planting of light weight or chaffy kernels,
6)Avoid ridge-planting especially to prevent Rhizoctonia
infection.
7) Planting should be done preferably at a time when soil
temperature is more than 10°C.
•
•
•
•
•
30. 1. Disease appears as small and diamond shaped
lesions on leaf and as they mature, they
elongate.
2. Increase in width of lesions is restricted by the
adjacent veins
3.Finally lesions typically assume rectangular
appearance.
4.Lesions are reddish brown in colour with dark
brown borders.
5.Symptoms may be confined largely to leaves
(race O) or may develop on leaves, sheaths,
stalks,husks,and cobs.
Symptoms
31. Disease cycle
Disease is favoured by high relative humidity and
warm temperature (25-32°C).
Pathogensurvivesin plant debrisandcollateral hostslike
sorghum,wheat, barley, oats, teosinte andother grasses.
Disease management
1). Cleancultivation mayreduceearly infection.
2) Useprotective fungicidesDithane-Z-78, Dithane M-45) @2.5
g/l assoonasfirst symptomsof the disease appear.
3)Growresistant maizecultivars,suchasDeccan,Deccan-103,
Ganga-5,Deccan-101,VL-42, Ganga-4.
32. Fusarium stalk rot
symptoms
Two species, F
. moniliforme and F
.
graminearum are associated with the
disease.
The incidence of the former is more severe
in low land tropical areas while the
latter is present in cooler highlands.
The symptoms become conspicuous when
the crop enter senescence phase i.e.
kernels are in ‘blister’ stage to the
phase when dry matter is near
maximum.
33. Fusariumstalkrot
Pathogen
commonly affects the roots, crown region and lower
internodes,
when split open, the stalks show a pink-purple
discolouration In plants affected by F. graminearum,
blue purple mycelial mat of Gibberella zeae develop
on the rind.
Diseasemanagement
• Crop rotation and avoid water logging
• Seed treatment with carbendazim or thiram @ 3 g/kg
• Soil application of organic amendment will reduce
inoculum
35. Charcoal stalk rot
(Macrophomina phaseolina)
This disease is prevalent comparatively in drier maize
growing areas.
The symptoms of the disease becomes apparent as the
plants approach maturity.
Affected plants dry prematurely, the affected
internodes become straw coloured, pith becomes
disintegrated.
Presence of small pin-head like black sclerotia on
the rind of the stalks is a distinguishing character.
36. Charcoal stalk rot (Macrophomina phaseolina)
FAVOURABLE CONDITIONS Water stress at or after
flowering has been found to predispose the plants to
infection.
debris.
The fungus survives in soil and plant
The pathogen has wide host range. Development of
charcoal rot is favoured by dry weather with high
temperature (37°C) at the time of silking
Imbalanced fertilizer application and high plant
density influence disease prevalence and severity.
37. Disease management
1) Plant resistantmaize cultivars,such as Ganga 9, Deccan 101, Him128,
Kanchan,Diara Composite, Hunius Compositeand Sangam.
2) Fieldsanitation andcrop rotation
3) Seed treatment with carbendazimor thiram or carboxin @ 3 g/kg
or Trichodermaharzianum@6 g/kg.
4) Charcoalrot canbeminimizedbymaintainingmoistsoils,especially
duringdryperiodsafter tasselling byproviding copiousirrigation.
5)Apply balanced fertilizer doses and avoid high doses of N, apply
optimum level of potash,
6) Plant population should be kept at a lower level, i.e., upto 50-60
thousandplantsper hectare.
7) Croprotation with paddyor sesamum.
8) Soilapplicationof organicamendmentandgreen manuring.
39. Common rust (Puccinia sorghi)
symptoms
• It is most conspicuous when plants approach
tasseling.
•
•
•
It is recognized by small, oval to elongate pustules.
Pustules are brown in early stages of infection;
later, the epidermis is ruptured and the lesions turn
black as the plant matures.
Alternate host (Oxalis spp.) are frequently infected
with light orange coloured pustules.
•
•
susceptible under artificial inoculations
Oxalis corniculata has been found to be
with
teliospores in India.
40. Disease management
1) Select resistant maize cultivars for planting in
areas where rust becomes problem,
e.g., DHM-1, DHM-103, Ganga 5.
2) The severity of the disease during rabi season
can be reduced by spraying mancozeb or zineb
@ 2.5 g/l, or hexaconazole / propiconazole @
1 ml/l.
The first spray should be given as soon as rust
pustules appear on the foliage and then two or
three more sprays at 10-15 days intervals.
41. Banded leaf and sheath blight
(Rhizoctonia solani f.sp. sasakii)
42. Banded leaf and sheath blight (Rhizoctonia
solani f.sp. sasakii)
Symptoms of this disease which
develop on leaves and sheaths are
characteristic concentric spots that
cover large areas of infected leaves
and husks.
Themain damage in the humid
tropics is a brownish rotting of
ears,
which
brown
show conspicuous
cottony mold with
light
small,
round, blacksclerotia.
The developing ear is completely
damaged and dries up prematurely
with cracking of thehusk leaves.
43. Disease management
1) Clean cultivation and destruction of crop
debris
2) Stripping of lower 2-3 leaves along with
their sheaths reduces the initial
inoculum.
3) Spray carbendazim1 g /
l or propiconazole 1 ml /
l.
45. Bacterial stalk rot (Erwinia
carotovora f. sp. zeae)
• Symptomsappear assofteningof basalinternodes:
•
•
Plantsmaywilt andemit fermenting odour:
Earsmaybecameblighted and rot.
• Thehighincidenceof this diseaseis favoured
• by high temperature (28°C and above) and high
ambient moisture
• which commonly prevail in most of the maize
growingareas3 to 4 week after planting.
46. Disease management
1) Grow resistant hybrids and composites such as
hybrid Ganga Safed,
2) Avoidance of water logging, provide proper drainage.
3) Planting should be done in the second fortnight of
June. It helps in reducing stalk rot incidence in
northern states of the country. Planting of the crop on
ridges rather than in flat soil is advocated.
4)Provide balanced fertilizers, especially potash, which
helps in making the plants more resistant.
47. • 5) Apply chlorine water irrigation (100-1000 ppm)
when the crop is at pre-flowering stage of the crop
(4-7 week cropstage).
• This pathogen is highly sensitive to chlorine.
Efficient control of this diseasebyusingbleaching
powder (CaOCl2H2O2 containing 33% chlorine) @
3.3 g per 10 liters of water could be obtained by
drenching of basal stalk region when plants are at
knee-high stage
• Resistance to this disease has been identified in CM
104 andCM 600.
48. Maize mosaic stripe virus: M Stp V.
Vector leafhopper Peregrinus maidis
Virus diseases
Maize Dwarf Mosaic Virus
49. Virus diseases
Three viruses occur on maize in India.
These are : maize mosaic virus I, maize
mosaic and vein enation. Maize mosaic
has been found to be prevalent in several
states and the incidence ranges from 2.2
to 10.6%. Resistance of a high order has
been identified in inbred lines CM 103 and
CM 1 04. The released cultivars have not
been reported to suffer much from viruses.
50. Maize Chlorotic Dwarf Virus
Symptoms:
• Leaves may be reddish and yellow, but this will depend on
environment,hybrid, or time of infection
•Veinbanding occurs when young leaves become chlorotic within
the whorl
• Plantsmaybestuntedandinternodesmaybeshortenedor stunted
•Leavesmayalsobetorn, twisted or haveswollenveinswith a dull,
roughsurface
• Plantsmayalsobeinfected with maizedwarf mosaic virus
51. Disease Management:
Use tolerant or resistant commercial corn
hybrids.
Control of Johnson grass with herbicides may be
beneficia
52. •Maize Dwarf Mosaic Virus
Symptoms:
•Symptoms often begin as chlorotic spots and
streaks on green, young leaves, which later
develop into amottle or amosaicpattern
•Viral strain, corn genotype, and stage of corn
development at the time of infection will affect
the type ofsymptoms
•Upper internodes of corn may be shortened, and
excessivetillering mayoccur
•Ear formation and development may slow, which
may causegrain yield loss
•Hybrids infected early in their growth stage may
be stunted
53. Timeof Occurrence:
Symptoms appear six weeks after aphids feed and transmit
this virus
DiseaseManagement:
Usetolerant commercial corn hybrids
Avoidance of aphidvectors
Control of Johnsongrasswith herbicides may bebeneficial
54. CORN INTEGRATED DISEASE
MANAGEMENT
• Managing corn diseases requires an integrated approach to limit disease
and yield losses. The use of disease-resistant hybrids, crop rotations,
various tillage practices, balanced fertility, fungicides, control of other
pests and weeds, and various other cultural practices is needed to provide
the broadest spectrum of control of corn pathogens. Table 14.3 lists
diseasesknown to causeyield lossesin Illinois and the relative
effectiveness of various controlmeasures.
Planting disease-resistant hybrids. The use of resistant hybrids is the
most economical and efficient method of disease control. Although no
single hybrid is resistant to all diseases, hybrids with combined resistance
to several major diseases are available. Corn producers should select high-
yielding hybrids with resistance or tolerance to major diseases in their
area.
•
55. • Rotating crops. Many common pathogens require the presence of a
living host crop for growth and reproduction. Examples of such corn pathogens
include many of the foliar diseases (Helminthosporium leaf diseases,
Physoderma brown spot, Goss’s wilt, gray leaf spot, eyespot) and nematodes.
Rotating to nonhost crops (i.e., soybean) “starves out” these pathogens,
resulting in a reduction of inoculum levels and the severity of disease.
Continuous corn, especially in combination with conservation tillage practices
that promote large amounts of surface residue, may result in severe outbreaks
of disease.
• Tilling. Tillage programs that encourage rapid residue decomposition before
the next corn crop is planted help reduce population of pathogens that
overwinter in or on crop debris. Although a clean plowdown is an important
disease-control practice, the possibility of soil loss from erosion must be
considered. Other measures can provide effective disease control if
conservation tillage is implemented. Examples of diseases partially controlled
by tillage include stalk and root rots, Helminthosporium leaf diseases,
Physoderma brown spot, Goss’s wilt, gray leaf spot, anthracnose, ear and
kernel rots, eyespot, andnematodes.
56. • Managing fertility. Balanced fertility and fertility levels play an
important role in development of diseases such as Stewart’s wilt,
seedling blights, leaf blights, smut, stalk rots, ear rots, and nematodes.
Diseases may be more severe where there is excess nitrogen and a
lack of potassium, or both. Healthy, vigorous plants are more tolerant of
diseases and better able to produce a near-normal yield.
Using foliar fungicides. The decision to apply a foliar fungicide should
be based on the levels of disease incidence and severity and on certain
risk factors. Factors that increase the risk of foliar diseases include
these: previous crop was corn, or corn debris on the soil surface is
prevalent; weather was rainy in July and August, with high dew points;
a susceptible hybrid was planted; and the crop was planted later than
normal
•
57. Disease rating scales for foliar diseases of Maize (1-5 scale)
(Turcicum leaf blight, Rust, Maydis Leaf blight)
Grade Degree of infection
1 Very slight infection, one to two restricted spots
(lesions) on lower leaves or traces
2 Slight to moderate infection on lower leaves a few
scattered lesions on lower leaves
3 Abundant lesions on lower leaves, few on middle
leaves
4 Lesions abundant on lower and middle leaves
extending to upper leaves
5 Lesions abundant on all leaves. Plants may be
prematurely killed by blight/ rust etc.
58. Disease rating scales for post flowering stalk rots of Maize
(1-9 scale)
Grade
1
2
3
4
5
6
7
8
9
Degree of infection
Internode discolouration very slight (traces)
25% of internode discoloured
25-50% of internode discoloured
50-75% of internode discoloured
75-100% of internode discoloured
1/2 discolouration of adjacent internodes
Discolouration of three internodes
Discolouration of four internodes
Discolouration of five internodes. Plant dries
completely and lodge
59. CONCLUSION
Diseases of maize are strongly influenced by weather conditions and are
very difficult to predict.
They are best controlled by the use of resistant or tolerant hybrids and a
balanced fertility programme.
Most of the disease causing agents/ pathogens has the capacity to over
winter and tillage and crop rotation are common cultural practices which will
help to reduce sources of disease organisms, particularly if disease has
been prevalent from the previous years.
Integrated disease management practices involving, cultural, biological and
chemical approaches will be of immense help to reduces losses caused by
maize diseases.
60. •
•
REFERENCES:
Maize crop science
by S C Panda
Crop diseases
By L Darwin christdhas Henry
Thiru h lewin
orgprints.org/8206/1/Integrated_disease_management-jkohl.pd
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• link.springer.com/article/10.1023%2FA%3A1009694632036