2. Cultural
Strategies for
Nematode
Management
Nematode Management With Plants
No plants โ fallow
Nonhosts โ crop rotation
Green manure cover crops
โข Trap crops
โข Resistant cultivars
โข Timing of planting and harvest to avoid
damage
โข = โescaping in timeโ
Antagonistic plants
3. ANTAGONISTIC PLANTS
A number of plants are antagonistic to nematodes. Mechanism of
โantagonismโ is not always clear.
Need more study as potential sources of suppression.
Used as a rotation crop, cover crop, or an intercrop.
Some are simply โnonhostsโ due to some biochemical or physical
incompatibility between the nematode and the plant.
4. ANTAGONISTIC PLANTS
โข However, others appear to produce some
kind of chemical exudate that acts
nematicidal.
โข In other cases, the growing plant is not
particularly nematicidal, but the
decomposing plant, when incorporated as
a green manure, displays nematicidal
properties.
โข Rapeseed is a host for Pratylenchus
penetrans but a green manure amendment
of rapeseed tops can reduce
โข P. penetrans populations.
โข It may also be possible that the growing or
decomposing plant encourages microbial
antagonists.
5. ANTAGONISTIC
PLANTS
Will go through the more prominent examples.
Literature often hard to retrieve since most research is done and
published in undeveloped countries.
Information often comes from anecdotal observations.
Interest has increased as nematicides are lost.
โAntagonistic plantsโ have not been studied extensively in
countries but are commonly studied in developing countries.
6. Marigolds - Tagetes
Few nematodes reproduce well on marigolds. Apparently does not affect the eggs of cyst nematodes.
French marigolds - growth period of 3-4 months (16 varieties tested) necessary to reduce Pp populations.
marigolds reduced Pratylenchus penetrans; yield of the following crop of Daffodil was doubled.
Population decline is due to nematicidal action of root-diffusates (terthienyl and bithienyl compounds)
dose = 0.2-5 ppm!
Kill in soil?
Have to be careful!
Sap and diffusates can burn skin, can also be phytotoxic.
7. EFFECTS OF GREEN MANURE COVER CROPS ON
PRATYLENCHUS PENETRANS
4500
4000
3500
3000
2500
2000
1500
1000
500
0
D-ESSEX TRUDAN STEPTOE SAIA
Unclipped
Clipped
NEMATODES/POT
Population Densities 16 weeks after Planting
**
Plants were clipped to 10 cm at 8
and 12 weeks to simulate mowing
Initial Density
TANGIA
Marigold
8. C
r
u
c
i
f
e
r
a
e
Sinapsis alba = white mustard
Brassica hirta = white mustard, called yellow mustard
Brassica nigra = black mustard
Lepidium sativum = cress
All inhibited emergence of Globodera rostochiensis
Suppress Meloidogyne chitwoodi, Stubby-root?
Attributed to isothiocyanate (remember MIT?) from
glucosinolates in root diffusate.
9. Asparagus
Produces glycoside โaspargic acidโ
Inhibits juvenile emergence from cyst eggs and is
toxic to several nematodes.
Reduced numbers of Paratrichodorus minor and
systemic nematicidal properties when sprayed on
tomato roots.
10. Crotalaria
Crotalaria juncea โ Sunn Hemp
Being used as a cover crop in tropical and
Crotalaria spectabilis (Rattlebox) = suppress
when used in various cropping sequences.
May be due to the alkaloid monocrotaline =
pyrrolizidine ester
Inhibited mobility of Meloidogyne incognita.
However, other plants with this compound are
susceptible.
11. Neem
๏ตMany medicinal properties :
โNatureโs Drugstoreโ Parts of the
plant as well as seed-cakes (seed
remnants after oil is removed) are
highly nematicidal. .
12. Nee
m
Inhibit hatching of M. incognita.
Intercropped seedlings suppress Meloidogyne incognita and Rotylenchulus
on tomato as well as Tylenchorhynchus brassicae on cabbage and cauliflower but
living nematodes remained high. Root exudates seem to be toxic to many
13. Neem
Mixed
cropping with
neem is often
impractical.
An organic amendment with neem seed-cakes is a
little more practical.
Neem may serve as a model for developing new
control strategies and new nematicidal compounds
that could be commercially produced.
This stresses the importance of plant diversity and
looking for naturally occurring compounds.
Often nematode control with an antagonistic plant
can be enhanced by incorporating it as a green
manure.
14. Cultural
Strategies for
Nematode
Management
Nematode Management
With Plants
No plants โ fallow
Nonhosts โ crop rotation Green manure cover crops
Antagonistic plants
โขTrap crops
โขResistant cultivars
โขTiming of planting and harvest to avoid
โข= โescaping in timeโ
15. Trap
Crops
Plants which are good hosts for
sedentary parasites. Nematodes
are allowed to infect the plants,
and then the plants are killed,
trapping the nematodes inside
where they die before they can
eggs.
Particularly effective for species
that require a host exudate to
hatch (i.e. cyst nematodes)
Does not work for ectoparasites
or migratory endoparasites that
are not โtrappedโ in roots.
Initial concept was to use
susceptible commercial
which could result in
increase if the plants were not
killed before females laid eggs.
16. Trap
Crops
Recently, cultivars have been
specifically as trap crops (radish for
sugar beet cyst nematode). These
cultivars may be attractive to the
nematode for invasion but may lack
nutritional requirements for females
develop and lay eggs.
This allows the plant to be grown
longer and provide some of the other
benefits from cover crop such as
building organic matter, weed
suppression and increasing
microbial populations.
Practiced more in developing
17. Susceptible Tobacco as a Trap Crop to
Reduce Tobacco Cyst Nematode
%
of
Starting
Density
140
120
100
80
60
40
20
0
3 WKS 4 WKS 5 WKS 6 WKS 13 WKS
Period of Growth Before Plant Destruction
LaMondia, 1996
18. 140
120
100
80
60
40
20
0
Tobacco as a Trap Crop
to Reduce Tobacco Cyst Nematode
Susceptible
Resistant
%
of
Starting
Density
3 WKS 4 WKS 5 WKS 6 WKS 13 WKS
Period of Growth Before Plant Destruction
LaMondia, 1996
19. Cultural Strategies for Nematode
Management
Nematode
Management With
Plants
No plants โ
fallow
Nonhosts โ
crop rotation
Green
manure
cover crops
Antagonistic plants
โขTrap crops
โขResistant cultivars
โขTiming of planting and
harvest to avoid
damage
โข= โescaping in timeโ
20. Nematode
Management by
Early Planting
and Harvest
Nematodes are limited by
cool soil temperatures.
For crops that tolerate
temperatures
planting early can give
crop a โhead startโ before
temperatures allow
nematode activity to
substantial damage.
Once the crop develops a
sufficient root system it
tolerate a moderate
of nematodes when they
become active.
Earlier planting can also
result in an earlier harvest
and crops can be removed
before damage can occur.
21. Examples
Planting early when it is cool
allows the plant to develop a
robust root system that can
tolerate a larger nematode
population when soils warm
Sugarbeet seed germinates at
spring temperatures before
beet cyst nematode (Heterodera
schachtii) becomes active.
22. Examples
Fall-planted cereals are larger than
spring-planted cereals when
begin infecting roots so plants
nematodes better, are not as stressed,
and yield reduction is less.
Cereal cyst nematode (Heterodera
avenae) hatch and infect roots in the
spring.
23. Examples
The first generation J2 of
Northern root-knot
(Meloidogyne hapla) infect
roots of potato when soil
temperature is warm
Second and later generations
infect tubers as well as
potato is planted and
harvested early, you can
most or all nematode
of tubers.
Any nematodes in tubers will
not develop in storage
temperatures are too cool,
symptoms will not be
expressed.
24. Examples
Columbia root-knot nematode also can
continue to develop under some storage
temperatures so symptoms can be
storage.
Therefore, second generation J2 emerge
and infect tubers before they are large
to harvest.
This will not work for Columbia root-knot
nematode which becomes active at cooler
temperatures and infects potato roots much
earlier.
