Agriculture Reference
In-Depth Information
tuberosus
Caldas), quinuas (
Chenopodium quinua
Willd.), and barley (
Hordeum vulgare
L.), have
proved successful for PCN control (Franco
et al
.,
1999). However, the high genetic variability in
these crops needs to be considered.
The possibility of reproduction (or not) in
the plant by the target nematodes or other PPNs
must be established in order to use trap cropping
as a strategy. Additionally, with PCNs, the use of
trap cropping during the same year of the potato
crop will not be effective, because of the dia-
pause these nematodes undergo. Trap cropping
is an option where PCN infestations are very
large and need to be reduced quickly, because
the technique is costly and requires very careful
management (Lane and Trudgill, 1999).
nematicides. Fumigant nematicides release toxic
gases that kill dormant juveniles inside cysts, egg
masses, or active nematodes, and they must be
used prior to planting, while granular nemati-
cides can be applied at planting. These com-
pounds prevent the hatched juvenile nematodes
from finding and invading the growing potato
roots. Fumigants are better suited for reducing
high nematode population levels (Lane and
Trudgill, 1999). However, nematicides (particu-
larly fumigants) are not specific and can have
broad effects on the soil communities, which in
turn can have detrimental effects on plant
health and development. Non-fumigant nemati-
cides (granular) are more influenced by how
well the granules are incorporated, and the best
way to do that is by using a powered rotator cul-
tivator (Lane and Trudgill, 1999). Global posi-
tioning systems have been investigated for use
with targeted application of nematicides in “hot-
spots” in the field; however, this has been of
limited success because the nematode infest-
ation is likely to be present elsewhere in the field
below detectable levels. Non-fumigant nemati-
cides are usually more effective than fumigants
in the control of stubby-root nematodes because
they are applied deeper in the soil. The best re-
sults are obtained at planting, when most stub-
by-root nematodes are in the upper soil layers,
provided that irrigation or rain does not wash
them into deeper levels (Strand, 1986).
Control of
G. pallida
, which has an extended
hatching period compared with
G. rostochiensis
,
influences the efficacy of nematicide control
(Hockland, 2010). For this reason, it is import-
ant to identify correctly the PCN species found in
the field. In other cases, the vertical migration of
species can be an important factor in the effect-
ive performance of pesticides applied in soil.
Populations of
M. chitwoodi
have been detected
as deep as 180 cm (Santo
et al
., 1985).
Seed pretreatment and disinfestation
The possibility of potato disinfestation has been
studied for
P. brachyurus
by treating the tubers at
50°C for
40-60
min (Koen, 1969). Excess soil
adhering to the tubers must be left in the field,
and removal of soil by high-pressure washing or
brushing until practically free of soil is not
wholly effective but should minimize the risk of
spread (Hockland, 2010). Low-temperature pre-
treatment of potato tubers for short periods has
been reported to increase plant tolerance of sub-
sequent low field temperatures, decrease PCN
multiplication, and increase crop productivity
(Matveeva
et al
., 2010).
Nematicides
Nematicides, if used, must be included in an in-
tegrated pest management program (IPM) and
not used as the only solution to PPNs. Also, due
to toxicological and environmental issues, their
use is being restricted in many countries and
their availability reduced. National require-
ments in terms of nematicides can also differ; for
example, in Spain the use of fumigants is not
permitted, only ethoprophos and oxamyl (MAA-
MA, 2012).
Two main kinds of nematicides are avail-
able in potato: fumigant and non-fumigant.
They have a restricted range of application con-
ditions (i.e. soil type, water conditions, tempera-
ture), and these conditions are generally more
restrictive for fumigant than for non-fumigant
Plant resistance
Host-plant resistance is an environmentally
friendly method of nematode control; however,
cultivars are often not available with the appro-
priate agronomic characters, and repeated use
of resistant cultivars in the same field can lead to
the selection of other PPN species, or virulent
pathotypes, negating their utility. PCNs and
