foliar nematodes

1
foliar nematodes

• nematodes in soil
• move to leaves
• under conditions of high humidity
• easily spread from plant to plant

2
Seed nematodes
Nematodes feed inside young seed ovules and lay
eggs. Eggs hatch and the juveniles undergo
anhydrobiosis as the seed head dries.
3
nematodes rehydrate when seed is planted and
infect new plants
nematode
4
Pine wood nematode
symptoms
Can be serious problem in urban areas, golf
courses
nematode
Nematodes use long-horn beetles to disperse. They
enter insectlarvae and are carried in their
respiratory system.
beetle vector
5
survival strategies for soil nematodes

• stay in place and deal with it root lesion
  cyst
• move to a better place sting needle
• use multiple strategies root knot

6
dispersal
Nematode standing on its tail waiting to attach
to a passing insect.

• plant material
• soil
• wind
• water
• animals

Genera that desiccate can be carried by wind.
7
Diagnosing a nematode problem

• signs or symptoms
• field scale symptom patchy areas of distressed
  plants or weeds
• may vary in severity from year to year, but
  doesnt go away
• often the last thing people think about
• definitive diagnosis soil sample

8
Aggregated distribution
9
Nematodes and crop loss

• Nematodes as only pathogen
• Interactions with other pathogens
• Disease complexes
• Nematodes as vectors
• Bacteria
• Viruses

10
nematode / fungus interaction nematode alters
host response to fungus
fungus
nematode fungus
check
nematode
11
Leaf life span greatly reduced by the combination
of V. dahliae and P. penetrans
12
nematode / bacteria interaction nematode is
vector for bacteria
bacteria
Nematodes carry bacteria on their cuticle. The
bacteria release toxins harmful to animals
nematode
13
nematode / virus interactionnematode is vector
Nematodes carry virus particles in their
esophagus. Only some genera of nematodes are
virus vectors.
tobacco ringspot
corky ringspot
14
Managing Nematodes

• Exclusion quarantine
• example potato cyst nematode
• Sanitation nematode-free seed
• example potatoes, wheat gall nematode
• Chemical control
• mostly high value crops
• Cultural control
• example host resistance
• Biological control
• antagonism

15
SOLARIZATION
16
exploit natural enemies no- or reduced tillage
nematode trapping fungus
egg parasite
17
Predator tardigrade
18

• Nematode carries bacteria into insect
• Bacteria kills insect
• Nematode eats bacteria multiplies