PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
Plant quarantine. contd
Australian quarantine. Many Phytophthora spp.
and other root rots pose a threat to Australia, eg
– Sudden oak death (P. ramorum) has a broad host
range of conifers, shrubs, herbaceous plants and ferns.
The Californian Oak Mortality Taskforce (COMTF)
aims to research the management of P. ramorum.
– Texas root rot (Phymatrochium onmivora) is a
destructive soilborne disease of >200 plants
including cotton, grains, fruit, eg apple and pear,
citrus, nuts, vegetables, nursery and garden plants.
– Biosecurity targets various crops and particular
diseases, including Phytophthora spp.
State/Regional. 500,000 hectares in WA are
under quarantine restrictions by the Forestry Dept.
in WA to prevent entry of infested soil on vehicles
coming from Pc-infected areas.
Local quarantine. Protocols developed for
production nurseries prevent contaminated seed,
plants and soil being brought into a nursery and
prevent contaminated plants, soil, etc being
supplied to growers, landscapers, fruit growers,
vegetable growers and cut flower producers
(BioSecure HACCP).
– Restrict movement of people, animals, vehicles
from contaminated areas to areas of highly
susceptible plants or in-ground production areas
maintained Pc-free.
– Avoid introducing Pc-infected plants, cuttings
etc to disease-free areas. Keep new plants separate
until their disease-freedom is established. This is
practical with container plants but difficult for
plants which are to be planted directly into soil.
– Movement of soil, either as deliveries, in
containers, adhering to tools, machinery. Footwear is
one of the commonest methods of introducing Pc
and other Pc to previously healthy areas.
. Disease-tested planting material.
Plant certified Pc-tested planting material
nursery stock and tube stock, into Pc-tested soil or
treated soil and irrigate with Pc-tested water and
keep it Pc–free. Monitor parent stock used for
propagation for infection and identify unwitting
introductions. Although Pc is not generally
seedborne, some other Phytophthora species may be
seedborne on some hosts.
Table 67. Phytophthora spp. – Some fungicides.
What to use?
Foliage sprays.
Group 33, eg Anti-Rot , Aus-Phoz , Phospot , various
(phosphorous as acid) – systemic
Soil applications (drenches, granules).
Group 4, eg Ridomil Gold, various (metalaxyl-m);
Fongarid (furalaxyl) – both systemic
Group 14, eg Terrazole (etridiazole) - non-systemic
Group 33, eg Aliette , Signature (fosetyl present as the
aluminium salt); Phospot (phosphorous acid) –
both systemic
Mixed formulations, eg
Group 1/14, eg Banrot (thiophanate-methyl/etridiazole)
which is effective against Phytopthora, Pythium,
Rhizoctonia & Chalara (Thielvaliopsis) –
systemic/non-systemic
Group 14/14, eg Terraclor Super X EC (etridiazole/
quintozene) – non-systemic for seedlings
Trunk injections.
Group 33, eg Phospot , various (phosphorous acid).
Stem canker topical applications.
Group M1, eg certain copper fungicides
Fruit rots.
Group M4, eg captan
Disinfectants
Seek advice regarding disinfectants for your situation (page 343)
370 Fungal diseases - Examples of fungal diseases
Nursery accreditations schemes in some states,
eg WA, ensure Pc–freedom in products sold.
When purchasing land for production of plants
susceptible to Pc, check it is Pc-free.
Physical & mechanical methods.
Disinfest irrigation water especially when it is
drawn from surface water or is recycled (page 373).
Pre-plant pasteurization of contaminated soil/media
is described on page 330.
Pre-plant soil solarization, correctly implemented,
prior to planting, may assist control of some disease
organisms (pages 330, 438).
Fungicides.
Remove/destroy infected plants before treatment.
If replanting an infected area seek advice.
Fungicides do not substitute for good cultural
practice and hygiene. Although some fungicides
(Table 67 below) are registered to control Pc, in
reality they mostly suppress and do not eradicate
Pc in soil or water. Even during foliar sprays,
sporangia and zoospores may still be produced from
some infected plants. So although sprays slow down
disease development, disease may still spread.
Longevity and the depths at which Pc occurs in soil,
precludes any attempt at chemical eradication,
although some fungicides can be used to contain
highly contagious sites and systemic fungicides can
be used to save slightly inured plants.
Fungicides such as phosphonate can protect trees
against infection, limit spread within the plant and
increase tree survival and yield. Phosphonate boosts
the plants immune system to cure and prevent new
infections.
Application. Depending on the situation, fungicides
may be applied by foliar sprays, soil drenches or
granules and stem injections. It is possible to treat
root rot disease by leaf applications but in some cases
equal or better control may be achieved by soil
applications or a combination of both soil and foliage.
Suckers have been dipped in fungicides. In WA
fungicides have been sprayed on foliage by mist
blowers and aerially from aircraft and helicopters.
Follow Croplife Science Resistance Management
strategies and label directions. Permits may be
required.
Fumigants (page 267).
When and how to apply?
Some plants injured by foliar sprays in hot weather.
Note that APVMA has suspended the supply or use of material and
products containing quintozene until 12 April 2011
Stem injection may provide rapid recovery in high value
crops and sites. Stem injections of phosphate protect
Banksia spp., E. marginata from Pc for at least 4 years
Apply to stems only whenever cankers appear after
removing dead tissue. Stem cankers are more difficult to
control than root rots.
Disinfect hands and footwear, and vehicles.