disease symptoms caused by plant parasitic nematodes

1. Nematode damage Symptoms in
Rice and Maize
Prepared by
R MOHANAPRIYA
Assisstant Professor (Plant Pathology)
JSA College of Agriculture and Technology,
Ma. Podaiyur, Cuddalore district, Tamilnadu

2. Rice
1.White tip nematode
Aphelenchoides bessyei
2.Rice root nematode
Hirschmanniella oryzae
3.Rice root knot nematode
Meloidogyne graminicola
4.Rice cyst nematode
Heterodera oryzicola
Maize
1.Lesion nematode
Pratylenchus sp.

3. Rice
White tip nematode – Aphelenchoides bessyei
Cause white tip disease.
Yield loss: 17.4- 54.1%.
Life cycle
 Quiescent stage -J2 present
beneath the hull of kernels.
 Dormant for 2 yrs.
 Feeds ectoparasitically.
 Eggs in leaf axils.
 Life cycle: 8-10 days (More
generation).
 Host: (Setaria italica, S. viridis,
Panicum sanguinale, strawberry,
tube rose)

4. Symptoms
 Seeds emerge late in seed
beds and produce small
seedlings
 Upper 2-5 cm leaf tips turn
white or pale yellow in the
tillering stage, then brown,
necrotic and frayed.
 Flag leaves are shortened and
twisted at their apical
portions.
 Panicles are shorter and
spikelets reduced in number.
 Terminal tissues of the panicle
are severely reduced and
produced small deformed
kernals.
 Maturity of panicle is delayed,
and secondary panicles may
arise from lower nodes if the
panicle is sterile.
Whitening and
necrosis of leaf tips
Twisted and crinkled
leaf tips

5. Management
• Resistant varieties such as TPS 1, TPS 2 can be grown.
• Presoaking overnight and sun drying for 12 hours at 6 hrs/day for two days, two or
three days prior to sowing to denematize the seeds.
• Hot water treatment of seed with 52 -53 degree C for 15 minutes can be used to
destroy this nematode infecting the seeds.
• Apply carbofuran 3G in nursery @ 1.0 kg a.i/ha 7 days before transplanting.
• Use nematode-free seeds and planting material.
• Rouging
• Chemical treatments of seed with Benomyl or Thiabendazole is being effective in
controlling nematodes.
• Spraying of infested crop with Parathion (.025%) and Trichlorophos (0.03%) three
times has been found to be effective.

6. Rice root nematode - Hirschmanniella oryzae
 Causes mentek / omomentek
disease of rice.
 Yield loss: 10-30%.
 Life cycle 30 days.
 Hosts: Echinochloa, Cyperus,
Monochlaria and Marsilia
Symptoms
 Arrested growth, poor
tillering, reduced number of
ear heads and grain weight.
 Reddish brown discoloration
of leaf.
 On the roots, the initial
necrosis intensifies and by the
time crop matures, the entire
root system appears brownish
and reduced in size.
 Formation of cavities in cortex
due to nematode feeding.
 The lesions and cavities
formed on the roots induce
root rot.

7. Rice root knot nematode,
Meloidogyne graminicola
 Yield loss upto 50%.
 Life cycle: 26-51 days.
Symptoms
 Swellings and galls throughout the
root system.
 Infected root tips become swollen
and hooked
 Severe growth reduction, unfilled
spikelets, reduced tillering,
chlorosis, wilting and poor yield.
 Symptoms often appear as patches
in a field.

8. M. graminicola is known to cause serious
damage to deepwater rice.
Prior to flooding, symptoms are the typical
stunting and chlorosis of young plants.
When flooding occurs, submerged plants
with serious root galling are unable to elongate
rapidly and do not emerge above the water
level.
Causes death of the plants leaving patches of
open water in the flooded fields.

9. Rice cyst nematode
Heterodera oryzicola
Symptoms
 Poor and patchy growth with
occasional death of seedlings.
 Reduced tillering in infected
plants and leaves show
discoloration and chlorosis.

10. Maize
Lesion nematode
Pratylenchus sp.
Symptoms
• The aboveground symptoms occur in
patches like that of root knot
nematode symptoms.
• Root damage by lesion nematodes
can be diagnosed by the presence of
small lesions on the root surface.
• Feeding of the nematodes on the
roots causes destruction of the
epidermis, where the root hairs are
formed.
• Cause severe necrosis and damage to
root hairs, which leads to a poor
uptake of nutrients and water by the
plant.
• Lesions caused by lesion nematodes
can also be infected with fungi and
bacteria (secondary infection).

11. Nematode damage symptoms in
pulses, oil seeds and cotton

12. Pulses
• Cyst nematode – Heterodera cajani
• Reniform nematode - Rotylenchulus reniformis
• Root knot nematode - Meloidogyne incognita

13. Pulses
Cyst nematode
Heterodera cajani
Symptoms
o Stunting, reduced leaf lamina size and yellowing on leaves.
o Flowers and pods are reduced in size and number and the root system are also
poorly developed. Foliage symptoms are not clearly visible
o Reduction in height and vigour of the infested plants can be observed when
compared with healthy plants.
o The disease is diagnosed by the presence of pearly white females on roots or
brown cysts in the soil.

15. Reniform nematode
Rotylenchulus reniformis
Symptoms
 Stunting, yellowing of leaves, wilting, reduction in size and number of
fruits are general symptoms.
 Below ground symptoms on roots include necrosis, destruction of feeder
roots.

17. Root knot nematode
Meloidogyne incognita
Symptoms
• Roots with galls of abnormal sizes are the major symptoms belowground.
• Patchy stunted growth of plants, wilt, discoloration and chlorosis of leaves,
reduced yield in quantity and quality and premature death of plants.

18. Oilseeds
Groundnut
Root-knot nematode
Meloidogyne spp.
Kalahasti malady
Tylenchorhynchus brevilineatus
Lesion nematode
Pratylenchus brachyurus

19. Root-knot nematode
Meloidogyne spp.
Distribution
In India, area under
groundnut is confined to five states
viz., Gujarat, Andra Pradesh, Tamil
Nadu, Karnataka and Maharashtra
and also Rajasthan, Uttar Pradesh,
Punjab and Orissa.
Symptoms
 Stunting, chlorosis, incipient
wilting, nutrient deficiencies and
distributed in patches of varying
sizes.
 Abnormal swelling of the roots
 Damage to groundnut pegs and
pods.
 Infected pegs are weaker, causing
the pod to be detached from the
plant during digging or harvest.

21. Kalahasti malady
Tylenchorhynchus brevilineatus
 Asociated with the Kalahasti
malady of groundnut. The
nematode may reduce the yield
of groundnut by 20-60%.
 First observed during 1976 at
Kalahasti region of Andhra
Pradesh, India and also been
reported from Tamil Nadu.
Symptoms
 Induces the disease “Kalahasti
malady”, which characterized by
reduction in pod size, brownish
discoloration of the pod surface
and appearance of small
brownish yellow lesions on pegs
and developing pods.
 Margins of lesions become
slightly elevated because of
cellular proliferation around the
site of nematode infection.
 Nematode infested pod stalks
were greatly reduced.
 Heavily infested pods become
completely discolored.

22.  The nematode does not affect the
seeds within the pods. Affected pods
become small, shriveled and show
ugly external appearance called
“Shutti kaya” in Telugu.
 Plant roots also parasitized but
discoloration is less severe than on
pods.
 High inoculum levels resulted in
symptoms like brownish to black
necrotic lesions on root surface, pod
stalks, pod surface and reduction in
pod size.
 Plants became stunted with dark
green foliage and necrotic lesions
could be seen on pod surface
 The disease is generally distributed in
patches within fields and more
severe in sandy soils.

23. Lesion nematode
Pratylenchus brachyurus
 First reported by Varaprasad and
Sharma, 1990 from Andhra Pradesh
Symptoms
 Small purplish brown to black lesions
appearing on the groundnut shell.
 The enzymes secreted through saliva
causes hydrolysis of plant protein to
hydrogen cyanide and benzaldehyde.
Both the end products are
carcinogenic and cause the lesions.
 The lesions have distinct boundaries
and first appear as small brownish
tunnels in the shell and later coalesce
to form large lesions.
 Help invasion of secondary soil
pathogens leading to greater necrosis
and rotting of pegs and pods.

24. Sunflower : M. incognita, M. javanica, Pratylenchus, R. reniformis
Castor : R. reniformis, Xiphinema sp.
Reniform nematode, Rotylenchulus reniformis
Symptoms
No diagnostic symptoms can be observed aboveground. In severe infestation,
stunting, yellowing of leaves, wilting, reduction in size and number of fruits
are general symptoms. Below ground symptoms on roots include necrosis and
destruction of feeder roots.

25. Gingelly : H. cajani
Cotton
• Stunting, delayed maturity, reduction in boll size and yield and reduction
in lint percentage.
• Stunted patches in the field having greenish leaves occur in nematode
infested cotton fields.
• The leaves of the reniform nematode infested plants have less reflectance.
• The nematode interact with Rhizoctonia solani and Fusarium oxysporum
pv. vasinfectum fungal diseases.

26. Nematode damage symptoms in fruit and
vegetable crops

27. Fruit Crops
Banana
Burrowing nematode
Radopholus similis
Lesion Nematode
Pratylenchus coffeae

28. Banana Burrowing nematode
Radopholus similis
Symptoms
Aboveground
 Dwarfing
 Yellowing and chlorosis of leaves
 Delayed flowering
 Smaller fingers, hands and bunches, reduction in bunch weight
Belowground
 Black, reddish brown lesion in root which can clearly seen when an
affected root is split longitudinally and examined immediately and
spreading to rhizome also
 Rottening of affected root system
 Toppling of trees even al low wind current due to poor anchorage.
 Splitting and cracking
 Causes Fusarium wilt disease when combined with Fusarium oxysporum
f.sp.cubens

30. Lesion Nematode
Pratylenchus coffeae
 Wounding of banana roots usually induce a characteristic
discolouration of the affected tissue.
 Brown cortical lesions develop and these are diagnostic symptoms
of the disease. These lesions are clearly seen when an affected root
is split longitudinally and examined immediately.
 Lesioning of the primary roots together with the girdling and death
of those roots which anchor the plant to the ground, makes the
plant prone to “tip over” under wind pressure.
Management:
• Deep summer ploughing.
• Selecting nematode free seed corms/suckers.
• Paring and pralinage with carbofuran 3G @ 40g/sucker (Dip the
corm in slurry solution of 4 parts clay + 5parts water and sprinkle
Carbofuran).
• Dip the corm with 0.5% Monocrotophos for 15 minutes, shade dry
for at least 24 hours and plant.

31. • Sow sunnhemp on 45th day, incorporate it after a month before flowering.
It reduces nematode build up.
• If pretreatment is not done, apply 40g of Carbofuran 3G around each plant
one month after planting.
• Remove the corms from the field after the harvest of bunches and keep
the field free of crop residues.

32. Citrus nematode
Tylenchulus semipenetrans
 “slow decline” and is considered to be one of the factors responsible for “die
back” disease of citrus trees in India.
 The annual reduction in the world citrus crop due to “slow decline” is estimated at
8.7 to 12.2 percent.
 In India it has been reported from Uttar Pradesh, Delhi, Punjab, Rajasthan,
Maharashtra, West Bengal, Assam, Himachal Pradesh, Sikkim, Orissa, Haryana,
Bihar, Karnataka, Tamil Nadu and Andhra Pradesh.
Symptoms
 Symptoms include general reduction in tree growth and vigour, yellowing and
shedding of leaves
 General symptoms of malnutrition (sparse foliage, small non uniform fruits,
defoliated branch ends) symptoms are particularly noticeable in the upper most
portion of a tree.
 Degree of decline and symptom expression may vary from tree to tree.
 Soil particles will usually cling tightly even after washing to the gelatinous egg
masses which cover the protruding part of the nematode body. So the roots look
larger in diameter in healthy roots. Actually the infested roots are slightly enlarged
at these places of infestation.

33. Management
 Application of carbofuran 3G @ 75g/ tree to control citrus nematode in
severe infestations.
 Application of 20g of Pseudomonas fluorescens / tree at a depth of 15cm
and 50cm away from the trunk once in 4 months.
 Application of neem cake @1 to 2 kg/tree depending upon the age of tree

34. Grapevine
Root knot nematode
Meloidogyne incognita
Symptoms
Aboveground
 Stunting, poor growth.
 Young shoots remain short and in severe attack the vines show defoliation.
 Reduction in leaf size, marginal drying of leaves.
 Reduced bunch weight
 The affected vines show decline in vigour with inadequate sprouting after pruning.
and perceptible reduction in the yield.
Belowground
 Small size galls along the feeder roots
 Heavily infested vines have a much reduced root system with large galls

35. Papaya
Root knot nematode
Meloidogyne incognita
Above ground symptoms
• Seedlings exhibit chlorosis, stunted growth
• Reduction in number of fruits, fruit weight and total yield
Below ground symptoms
• Galling of roots, small to medium size or sometimes even large

36. Vegetable Crops
Tomato, Brinjal, Bhendi and Chilli
Root knot nematode Meloidogyne incognita
Symptoms
 Seedling emergence, development and vigour affected
 Infested seedlings may not survive after transplanting
 Stunted growth
 Disease appears in patches under field condition
 Leaves show dwarfing, chlorosis and yellowing
 Day wilt
 Growth may be retarded

38. Potato cyst nematode Globodera rostochiensis and G.
pallida
Aboveground symptoms
 The foliage of infested plants has a sickly yellow appearance and the plant may die
prematurely
 Patchy appearance
 Stunting, yellowing, discolouration and wilting of the foliage under drought conditions
Belowground symptoms
 Early senescence and proliferation of lateral roots
 Small immature females of white and yellow stages can be observed on the roots at the
time of flowering stage.
 Reduce the tuber size and number

40. Carrot
Root knot nematode Meloidogyne hapla
Aboveground symptoms
• Stunting, chlorosis and yellowing of leaves
• The damage appears in patches under field conditions
Belowground symptoms
• Nematode induce small, more or less spherical, galls coupled with profuse
root branching originating from gall tissues resulting in a bearded root
condition
• Forking of tap root is an important symptom of this nematode.
• The infestation decreases the marketable value and girth of carrot
• Cracking and splitting of storage roots

41. Cabbage and Cauliflower
Root knot nematode, Meloidogyne incognita
Symptoms
Aboveground symptoms
• Stunted growth
• Yellowing of leaves
• Disease appears in patches under field conditions
Belowground symptoms
• Primary galls are small and induced by swelling, which coalesce to form
large secondary galls

42. Nematode damage symptoms in flowers, spices
and medicinal crops

43. Crossandra
Lesion nematode Pratylenchus delattrei
Aboveground symptoms
o Infected plants exhibit stunting with pinkish to purple and yellow coloured leaves
o The leaf tips dry and entire leaves turn yellow and shed
o The plants are devoid of side shoots and remain completely defoliated
o Inflorescence and flower size is also reduced
Belowground symptoms
o Root growth is retarded with brown to black coloured spindle-shaped lesions
o Nematode moves intracellularly and remains in cortical region
o Infestation results in dissolution of cell walls which leads to cavity formation in
cortical region
o Cell wall gets thickened and cell contents become more dense and granular.
Management
 Avoid planting crossandra in nematode infested fields.
 To control nematodes, application of phorate or carbofuran 3G @ 1kg a.i./ha a
week after planting and to be repeated six months after application with any one
of the above chemicals at 3 and 9 gm respectively per metre length.

45. Jasmine
Lesion nematode - Pratylenchus delattrei
 The lesion nematodes are migratory endoparasite invading the roots and
destroy the cortical cells. This leads to dark lesions on the root surface and
subsequently rotting of roots occur and then the nematode migrate to
invade fresh healthy roots.
 The infested plants show stunted growth and yellowing of leaves.
Management:
Apply 10g of Phorate granules near root zone and irrigate

46. Tuberose
Root knot nematode Meloidogyne incognita
Aboveground symptoms
 The affected plants exhibit yellowing, drying of leaves and retarded
growth
 In severely affected plants, the emergence of spike is also delayed /
suppressed.
Belowground symptoms
• Root growth is retarded with numerous galls on the roots

48. Turmeric
Root knot nematode Meloidogyne incognita
Aboveground symptoms
 Stunted growth
 Yellowing, marginal and tip drying of leaves
 Reduced number of tillers
 Infested plants age, dry faster and die prematurely, leaving a poor crop stand
at harvest
Belowground symptoms
 Infested rhizomes losse their bright yellow colour
 Root-knot nematodes caused galling and rotting of roots

49. Black pepper
Radopholus similis
Aboveground symptoms
 The primary symptoms of the slow wilt disease are the appearance of pale yellow or whitish
yellow drooping leaves on the vines
 Yellowing is followed by shedding of leaves, cessation of growth and dieback symptoms
 At very early stage the symptoms may disappear with the onset of south west monsoon
 However within 3-5 years of initiation of yellowing, all the leaves shed and death of the vine
takes place and hence the name „slow wilt disease‟
 In bearing vines, shedding of spikes is a major symptom
 Large number of dead spikes is seen at the base of affected vines.
Belowground symptoms
 The tender, white, feeding roots show typical orange or purple coloured lesions
 Lesions are not clearly seen on older roots, being brown in colour
 The root system exhibits extensive rotting and the main roots are devoid of fine feeder roots
that rot quickly
 Extensive necrosis of larger lateral roots develops subsequently

50. Cardamom
Root knot nematode Meloidogyne incognita
Aboveground symptoms
Nursery
• > 50% of the germinating seeds do not emerge as a consequence of infestation of the radicle and
plumule by second stage juveniles of root knot nematode
• At the two leaf stage show marginal yellowing and drying of leaves and severe galling of roots
• On transplantation to a secondary nursery they exhibit wilting of the unopened leaves
• These leaves mostly emerge after the breaking open of the pseudostem
• Upto 40 per cent of such seedlings do not establish in the secondary nursery
• In secondary nurseries the infested plants are stunted and yellowish with poor tillering, drying of
leaf tips and margins and heavy galling of roots.
Field
• Stunting
• Reduced the number of tillers
• Yellowing, premature drying of leaf tips and margins, narrowing of leaf blades
• Delay in flowering
• Shedding of immature capsules and reduction in yield
Belowground symptoms
• Galling of roots is not a conspicuous symptom on mature plants
• The infested roots, however exhibits a „witches broom‟ type of extensive branching

51. Medicinal crops
Sarpagandha, Senna, Ashwagandha, Bhumi amlaki, Makoy, Medicinal coleus (Coleus
forskohlii) and Geranium
Root knot nematode - Meloidogyne incognita
Aboveground symptoms
• Plant shows a gradual decline.
• Stunted plant growth, yellowing of leaves.
• In heavily infested soil, poor emergence and death of young
seedlings occur.
• Severe loss in biomass production
Belowground symptoms
• The root shows small galls which in case of multiple infections on
the nearby tissue may coalesce to form large galls
• Reduction in quality and quantity of economical parts such as
leaves and pods
• Nematodes induce changes in biochemical constituents present in
the roots
• Heavy infestation reduces the biomass of the roots