Nematode Diseases of Perennials
Symptoms & Signs
Dr. James A. LaMondia
Plant Pathologist/Nematologist
The Connecticut Agricultural Experiment
Station, Valley Laboratory
Windsor, CT
Nematodes Infecting Perennials
Meloidogyne hapla - root-knot
Aphelenchoides - foliar nematodes
Ditylenchus - stem/bulb nematodes
Pratylenchus - lesion nematodes
Nematode Diagnostics
30% (99 of 333) samples
submitted over 5 years
were infected with
Meloidogyne hapla
Perennial Ornamentals
> 2500 species in >500 genera.
Value over $1 billion in US.
Propagation by division, seed,
and cuttings.
Non-specific Damage
Symptoms of poor roots
Poor color and vigor
Reduce winter hardiness
Secondary pathogens/diseases
Nematodes Infecting Perennials
Meloidogyne hapla - root-knot
Aphelenchoides - foliar nematodes
Ditylenchus - stem/bulb nematodes
Pratylenchus - lesion nematodes
Nematodes Infecting Perennials
Meloidogyne hapla - root-knot
Aphelenchoides - foliar nematodes
Ditylenchus - stem/bulb nematodes
Pratylenchus - lesion nematodes
Nematode Diseases of Tree Fruits
Nematode Damage
Reduce tree vigor and yield
Reduce winter hardiness
Transmit viruses (TmRSV)
- apple union necrosis
- peach stem pitting
Replant Diseases
Nematodes Infecting Tree Fruits
Pratylenchus - lesion nematodes
Xiphinema - dagger nematodes
Criconemella - ring nematodes
Meloidogyne hapla - root-knot
Nematode Damage Levels
3
cm
Lesion - 25-150 per 100
soil
Ring - 50-200 per 100 cm3 soil
3
Dagger - 1-100 per 100 cm soil
(depends on TmRSV)
Apple Replant
Trees appear stunted, and growth
uneven and slow.
Associated with lesion nematodes,
soil fungi and bacteria, and poor
soil conditions.
Apple or Fruit Replant Disease
Ring Nematode
Apple Union Necrosis
Apple Union Necrosis
Problem only on size-controlling
rootstocks such as MM106 and
scions such as Red Delicious.
Shoot growth reduced, heavy set
of small fruit, not always lethal.
Tomato RingSpot Virus
History
Weed Hosts of TmRSV
Common chickweed
Lambsquarters
White-head aster
Oxeye daisy
Common thistle
Dandelion
Wild carrot
Swine or Pennycress
Leafy/prostrate spurge Red or White clover
Common polkweed
Buckhorn plantain
Common mullein
Common plantain
Sheep sorrel (red)
Curly dock
Wild strawberry
Broadleaf plantain
Peach Stem Pitting
Affected trees appear girdled, lose
vigor and eventually die.
Trees often yellow early, and set a
large number of small fruit.
Pits or grooves occur in rootstock.
Cultural Practices
• Site preparation
• Rotation crops - Brassicas or
sorghosudan/sudangrass.
• Sod strips - perennial rye or
fescue grasses and weed control.
Nematicides
• Need determined for each field
• Fumigant Nematicides
1,3-dichloropropene
metam sodium or dazomet
• Non-fumigant Nematicides
Fenamiphos or oxamyl
Strawberry Black Root Rot: Plant
and Pathogen Interactions
James A. LaMondia
The Connecticut Agricultural Experiment
Station
Valley Laboratory
Windsor, CT
DISEASE TRIANGLE
DISEASE
Environment
Effect of pathogens on root disease
and length
%BRR Structural
Feeder
None
10
526
1124
Rf alone
22
491
1440
Rf + Pp
46
411
654
Strawberry Root Types
Structural roots – 1° & 2 °
developed cortex.
Perennial roots – 2 ° tissues
root cortex sloughed off.
Feeder roots – 1 ° tissues
short-lived, quick cycles.
well
Pratylenchus recovery per g root
Root type
1997
1998
Perennial
1.2
23.5
Structural
27.8
118.1
136.6
335.0
1.2
8.4
Feeder
Soil
R. fragariae isolation %2mm roots
Root type
Spring
Harvest
Perennial
52
78
Structural
3
40
Feeder
12
27
Pp lesion
17
73
Nematode-Fungus Interactions Split
Root Experiments
pot 1
pot 2
Pp
None
None
None
Rf
Pp+Rf
Pp
Rf
Nematode-Fungus Split Root
pot 1
pot 2
%BRR
Pp
Rf
14 b
None
Pp+Rf
26 a
None
Pp
12 b
None
Rf
8 b
Nematode-Fungus Interactions
Rf and Pp associated with BRR.
Additive pathogen interaction.
Split root – local interaction.
Pp no effect on root exudates or Rf
growth in amended media.
Nematode-Fungus Interactions
Rf resident on strawberry roots.
Secondary growth > Rf infection.
Nematode lesions > Rf infection.
Pp, 2° growth cause cell death.
Rf infects dead cells  healthy.
Strawberry health
Root growth vs. root loss
Tolerance to BRR
Insect interactions, white grubs and
weevils - breeding
Management Research
Nonhost / antagonistic crops.
Effect of fertilizer/pH on BRR.
Fungicides - Root drench/dip trt
Biological control: PGPR; cvs.
IPM – nematode bioassay