PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
Resistant/tolerant cultivars, rootstocks.
Grasses are affected less often than broadleaved
plants and show little obvious galling.
Avoid planting susceptible crops in field
contaminated with root knot nematodes.
For many plant species, resistant
varieties have been developed, eg
– Tomatoes, the hybrids 'Red Supreme' and 'Rich
Reward' are tolerant to root knot nematodes.
– Rootstocks with resistance to root knot have been
used in the grape and stone fruits industries.
– Many pasture legumes, eg white clover are very
susceptible to root knot nematode.
– As new varieties of many crops are continually
being marketed, eg strawberries, they need to be
evaluated for their resistance to the various strains
of root knot nematode. Some varieties may be more
susceptible than others.
Plant activators activate a plant’s natural
resistance mechanisms. Certain amino acids
mixed into soil or sprayed onto plants may
increase local and systemic-induced resistance
to root knot.
Plant quarantine
Australian Quarantine and Inspection
Service (AQIS). Many species and strains
of root knot nematodes occur overseas which do
not as yet occur in Australia.
Interstate and Regional Plant Quarantine.
There are no restrictions on the movement of
plants or plant material infested with root knot
nematodes within Australia.
Local quarantine. Inspect tubers, rooted
seedlings and other plants if they are obtained
from a nursery or some outside source. Destroy
all plants in a batch if even of a few plants only
are infected. Preferably grow your own
seedlings and other propagating material.
Nematodes may be introduced in soil or manure
deliveries. Avoid spreading infested soil to clean
areas or planting infested plants in clean areas.
Disease-tested planting material.
If available, use it. If not it may be necessary to
treat propagation material (next column).
It is available for crops such as potatoes, seed
tubers being guaranteed free from virus and
other diseases, including root knot nematodes.
Disease-tested planting material must be planted
in nematode-free soil/media.
If disease-tested planting material is unavailable
only use propagation material preferably from
aerial plant parts of plants or from tissue culture.
Strawberries may become infected with one of
the 4 common species of root knot, M. hapla,
M. incognita, M. japonica and M. arenaria; the
formation of galls on strawberry roots does not
indicate M. hapla it may be a different species.
Ensure runners you plant are free from all these
species to prevent their introduction and spread.
Physical and mechanical methods.
Propagation material like bulbs and corms
can be treated with hot water, eg standard
treatment for Narcissus stocks is 3 hours at
44.4 o C. Some tulip cultivars can be successfully
treated but others are susceptible to damage.
Plants such as young rose plants with infected
roots can be freed, during dormancy, from
infection by washing off soil and dipping roots
in hot water for a prescribed period of time.
Soil can be pasteurized with aerated steam at
60 o C for 30 minutes to destroy plant parasitic
organisms but not beneficial ones. Avoid reinfestation
by planting nematode-free plant
material only in nematode-free soil/media. Most
potting mixes today do not contain soil.
Soil solarization. Root knot can be controlled
effectively in greenhouses with steam sterilizarion
of the soil or soil fumigation with nematicides.
Nematicides.
Few effective nematicides are available, Nemacur
(fenamiphos) will soon not be available for use in
turf in Australia (page 266).
One treatment provides satisfactory control for
one season only.
Nematicides are persistent and have a long withholding
period. Residues of Nemacur would be
detected above permissible levels in certain
vegetables during spot checks.
Chemical may be applied through the irrigation
system but with drip irrigation, especially on
sandy soil only the drip zone will be treated. So
nematodes beyond the drip zone will become
active when soil is moist. The whole area must be
thoroughly wet to a depth of 30-45cm. This is
difficult for growers with only drip irrigation and
with boom spraying it is difficult to put on the
volumes required.
Table 53. Root knot nematodes – Some nematicides.
What to use?
NON-FUMIGANTS - PRE- AND POST-PLANT
See page 266, Table 55
Group 1A, eg Temik (aldicarb); Vydate (oxamyl)
Group 1B, eg Nemacur (fenamiphos); Rugby (cadufos)
DANGEROUS POISON and POISON
FUMIGANTS - PRE-PLANT
See page 267, Table 56
DANGEROUS POISON and POISON
OTHERS
When and how to apply?
For use by appropriately trained operators only.
Mainly used on ornamentals
Ornamental, fruit, seed, tuber and vegetable treatments,
Only treat if monitoring indicates a need.
For use only by appropriately trained operators
prior to planting field areas. Could be used in greenhouses.
Fumigants which can be applied after planting are being
researched.
Only treat if monitoring indicates a need.
Many products are being researched overseas for controlling
nematodes in certain situations (Agrios 2005), eg
Mixing essential plant oils from plant spices into
nematode-infested soil before planting.
Abamectin, azadirachtin, methylene bisthiocyanate.
Nematode diseases 271