PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
Unwanted individual trees
Management
Seek advice and engage a qualified arborist for
trees taller than 3 metres.
Safety is the No. 1 issue. Is the tree defective?
Be familiar with relevent legislation.
Identification of the tree must be confirmed.
Know its height, diameter and whether it suckers.
Control methods
Legislation.
Be aware that there may be conflicting legislation
and opinions influencing unwanted trees.
Tree Preservation Orders or other legislation may
apply. Seek advice if in doubt.
Weed legislation. Contact your State/Territory
authority for a copy of the current list of declared
weed species which change from time to time as
more research is carried out. When a species is
discovered to be an environmental weed, what can be
done? Such a tree does not necessarily have to be
removed it, it may merely have to be prevented from
seeding (propagating itself).
How do you prevent a tree with a 20m diameter canopy
covered in seed from propagating itself is not usually
defined. Problem arises when local council may not
allow removal and owners don’t want to pay the cost
of annual pruning to remove seeds. Negotiate annual
pruning? Who pays?
Although it is preferable to kill trees prior to removal,
in an urban situation this is not usually acceptable.
Physical & mechanical methods.
Plants which do not sucker, eg conifers, can be
removed by cutting them off at ground level.
Trees or shrubs which do sucker, eg elm,
eucalypt, poplar, black locust, honey locust, tree of
heaven, wattles, willow and wisteria can be
eradicated by cutting down the tree or shrub and by
diligently removing the suckers over a period of
time, especially in a home garden situation.
However, suckers of some species, eg elm, poplar
and wisteria, may continue to appear for years after
the parent tree or climber has been removed.
Tree remains may be chipped and applied as
mulch, occasionally non-parasitic mushroom fungi
may grow on them, bio-degrading them.
Stumps adjacent to domestic buildings
should be removed as they may attract termites, or
wood rotting fungi which may later lift pavers, etc.
Herbicides.
Trees such as conifers which do not sucker after
removal do not require application of herbicide.
Cut stumps of trees that do sucker can be treated
with herbicide immediately after felling.
Great care must be exercised in the use of
herbicides to kill woody plants. Some have a long
residual life in the soil and so represent a hazard to
surrounding plants. Strictly observe label
recommendations for application methods.
Heavy rain soon after application may cause
herbicide to wash from treated stumps onto
surrounding plants and areas.
Although triclopyr is highly toxic to broadleaved
plants during growing and dormant periods, grasses
are normally unaffected and could establish quickly
after treatment. Roundup , Zero (glyphosate) will
kill both broadleaved and grass plants.
Table 85. Unwanted individual trees – Some herbicides.
What to use?
ALL TYPES OF TREE POISONING
Group M, eg Roundup ) (glyphosate)
OR
Group I, eg Garlon (triclopyr), Tordon Herbicide
Gel, Vigilant Herbicide Gel (picloram)
is applied directly from a container onto
cut stumps.
When and how to use?
BEFORE TREE REMOVAL
Preferably apply the herbicide prior to tree removal, but this may
not be practical (page 468, Fig. 255).
Follow label Directions For Use.
Trees must be actively growing and not under stress (drought,
waterlogging, cold).
Apply herbicide to the freshly cut surface as soon as possible
after frilling or notching.
In tree injection, the herbicide is immediately delivered into the
sap stream.
Do not remove the treated tree for at least 4 weeks after treatment.
to allow good translocation to the roots.
AFTER TREE REMOVAL
Cut and paint stump treatments (for trees which sucker).
Use when circumstances make it impractical to use frilling,
notching, tree injection.
Paint sapwood area of the freshly cut stump.
May not be as effective as frilling, notching or tree injection.
Weeds - Examples of weed situations 469