Nematodes in Grapes

1
Nematodes in Grapes

• Introduction
• Nematodes account for an estimated 14 of all
  worldwide plant losses, which translates into
  almost 100 billion dollars annually.
• Nematodes are translucent, microscopic
  roundworms, typically measuring 0.25 to 1 mm in
  length and only about 0.1 to 0.2 mm in diameter.
• Most nematodes in soil are beneficial components
  of the soil ecosystem, where they feed on
  bacteria, fungi and other micro-invertebrates,
  stimulating and regulating the turnover of
  nutrients.
• Their abundance ranges from about 1000 per liter
  of degraded or infertile soil, up to 50,000 per
  liter of highly fertile soil.

Root knot nematode invading plant roots Courtesy
www.agr.hokudai.ac.jp
End
Next
2
Symptoms of damage

• Plant-parasitic nematodes use hollow spear-like
  mouthparts called stylets to feed.
• Nematodes feed on root cells and disturb the
  uptake and movement of nutrients and water from
  the soil into the plant.
• The main symptoms of nematode damage are stunted
  growth, poor vigour and yellow leaves. These
  symptoms can be confused with nutrient
  deficiencies or moisture stress.
• Most species cause direct damage, including
  gall-like malformations that impair root function
  (root-knot nematodes) or dieback of root tips and
  
• formation of lesions on the roots (e.g
• root-lesion nematodes).

www.plantprotection.hu/modulok.
End
Previous
Next
3
Symptoms of damage

• A few nematode species do not cause much direct
  damage on their own, but can transmit viruses
  while they are feeding (e.g., dagger nematodes).
• When nematode population densities are large,
  root systems will be sparse, there will be few
  fine roots, and the damaged roots will appear
  reddish, brown or black rather than a healthy
  white colour.
• If root-knot nematodes are present, it may be
  possible to see characteristic swellings or galls
  on feeder roots.
• Vines severely damaged by plant-parasitic
  nematodes are stunted and have reduced yields.

End
Previous
Next
4
Life cycle

• The reproduction is by meiotic parthenogenesis.
• Males are very rare. Female lay 500 to 1000 eggs
  outside her body in a gelatinous sac, in late
  summer.
• The larvae develop into first stage juveniles in
  the egg sac, and root feeding occurs after
  emergence of the second stage juvenile (J2).
• Maturation and sexual reproduction occurs at the
  adult stage.
• Feeding larvae and adults are active throughout
  the growing season.

Egg masses of M. incognita (R. Gapasin).
Newly hatched Meloidogyne J2. Photo David McK.
Bird
End
Previous
Next
5
Nematode Species

• The most common genera of nematodes are detected
  in soils from vineyards are listed below
• Citrus nematode, Tylenchulus semipenetrans
• Lesion nematode, Pratylenchus penetrans
• Root knot nematode, Meloidogyne sp.
• Reniform Nematode, Rotylenchulus reniformis
• Dagger nematode, Xiphinema index

End
Previous
Next
6
Citrus nematode Tylenchulus semipenetrans

• Females are swollen, sac like, remain attached to
  roots with head region buried in tissues. Damage
  results in
• Drying of apical leaves, buds, twigs downward.
• Vines show reduced vigour, gradual reduction in
  yield.

Females of Tylenchus sp. Courtesy
nemweb.ucdavis.edu
Root lesion nematodes Pratylenchus penetrans

• Nematodes make cavities and tunnels by destroying
  the cells.
• Thin and dense fibrous roots are the
  characteristic symptoms of stubby root nematodes.

End
Previous
Next
7

• Root-knot Nematode Meloidogyne sp.
• The affected roots exhibit severe galling.
  Galling is the result of the proliferation of
  cells of the affected roots.
• In severe attack, the vines get defoliated.
• As a result of feeding, infested roots show
• Knot-like galls on roots.
• Stunted plants with chlorotic leaves.
• Reniform Nematode Rotylenchulus reniformis
• The nematodes mostly damage the secondary
• and the feeder roots. The affected roots
  show
• Brownish discoloration. The affected portions
• rot and get sloughed off.
• As a result the nutrient uptake is affected and
• the vine appears sick.

Root galls
Females and egg mass of R. reniformis Courtesy
plpnemweb.ucdavis.edu
End
Previous
Next
8
Dagger Nematode, Xiphinema index(Nematode- borne
or nepo virus)

• Xiphinema index, plant parasitic dagger nematode
  transmits grape fanleaf virus (GFLV) .
• Spread of virus occurs by two principal modes
  grapevine-to-grapevine spread in the vineyard by
  the nematode vector and, long distance spread
  via distribution of propagation material from
  infected grapevines. 
• The disease can cripple infected grapevine with
  misshapen leaves, short internodes, and poor
  berry set.
• All cultivars of wine grapes are susceptible to
  the disease and severe economic damage with yield
  losses up to 80 percent have been recorded in
  many sensitive cultivars.

End
Previous
Next
9
Typical symptoms of grapevine fanleaf viral
disease
fan-shaped leaves mimicking the ladys fan (and
hence the name of the disease) with toothed
margins, vein-banding and yellow mosaic symptoms
infected grapevines produced small clusters with
poor fruit set, irregular ripening and shot
berries 
Courtesy http//wine.wsu.edu/research-
End
Previous
Next
10
Management

• Nematodes are best managed before planting.
  Selection of planting material from nematode free
  nurseries.
• Application of neem or castor cake.
• Application of carbofuran 3G _at_ 50 g / vine and
  watering.
• Preplant soil fumigation with DD mixture and
  using clean nursery stocks.
• In infested orchards, soil drenching with DBCP
  (Dibromo chloro propane) is found to be
  effective.
• Crop rotation with Non-host crops or resistant
  crops can be planted when nematode population is
  high.
• Use of trap crops and antagonistic crops.
  Planting Tagetes erecta (African marigold)and
  Crotolaria spectabilis in nematode infested soil
  is effective against the root-knot nematode.

End
Previous
Next
11
Lets sum up

• Nematodes account for an estimated 14 of all
  worldwide plant losses, which translates into
  almost 100 billion dollars annually.
• Nematodes are translucent, microscopic
  roundworms, typically measuring 0.25 to 1 mm in
  length and only about 0.1 to 0.2 mm in diameter.
• The main symptoms of nematode damage are stunted
  growth, poor vigour and yellow leaves.
• Nematodes are best managed before planting.
  Generally, nematode infestations result in areas
  of the vineyard with vines that lack vigour and
  have restricted growth and reduced yields.
• Manures and other soil amendments can improve
  vine vigour and frequently reduce the effect of
  nematode infestation.

End
Previous
Next