PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
Tree suckers
A sucker is a shoot growing from adventitious buds at
the base of stems or rootstocks of some grafted trees
and shrubs, below ground stems, roots of trees,
shrubs, climbers, etc. Some trees produce suckers
from buds on the tree trunks, eg Prunus.
Tree types
Some species are prone to produce suckers from
underground roots, eg elm, eucalypt, poplar, black
locust, wattles, willow, wisteria.
Impact
Unsightly, may grow into garden beds, turf areas, rose
gardens.
Conditions favouring
Roots of some trees, eg cherry (Prunus spp.) may
sucker after injury, eg by digging, cultivation.
Some trees and shrubs sucker after heavy pruning, eg
citrus, lilac.
Drought may cause dieing back of upper portions and
suckering at the base and on trunks and branches.
Fire from control burning or which kills the upper
part of the tree.
Management (IWM)
Are you a commercial grower or home gardener?
1. Prepare a plan that fits your situation.
2. Crop, region. Recognize variations.
3. Identification of suckers must be confirmed. Know
what species of tree you are dealing with. Consult a
diagnostic service if unsure (page xiv).
4. Monitor development of suckers during the growing
season and their impact (page 429). Record results as
recommended.
5. Threshold. How much damage can you accept?
Have any thresholds been established? If so, what are
they, economic, aesthetic, environmental? Do you
need to calculate your own threshold?
6. Action. Take appropriate action when any threshold
is reached.
7. Evaluation. Review IWM program to see how well
it worked. Recommend improvements if required.
Control methods
Physical & mechanical methods.
Tree suckers in a home garden or small orchard
can be diligently dug out over a period of time. Cut
of cleanly where the base of the sucker arises from
the root. Note suckering on the trunks due to
drought, etc should also be cut off cleanly allowing
sap to go up the stem.
Herbicide treatments.
Herbicides used depends on whether the suckers
are still attached to the parent tree or not (Table 83
below).
Table 83. Tree suckers – Some herbicides.
What to use?
SUCKERS NOT ATTACHED TO PARENT TREE
Surrounded by turf, eg
Group I, eg Blackberry &Tree Killer , Garlon (triclopyr)
Not surrounded by turf, eg
Group I, eg Blackberry &Tree Killer , Garlon (triclopyr)
Group M, eg Roundup , various (glyphosate)
SUCKERS STILL ATTACHED TO PARENT TREE
Usually label rates apply to the control of suckers not attached
to the parent tree. Rates used to control suckers still attached
may be lower than label rates
Surrounded by turf or desired plants
When and how to use?
General procedures.
Suckers up to 1 metre high may be sprayed directly.
Larger suckers or those growing in close proximity to
desired species may be cut off at ground level and the
freshly cut surface treated with herbicide.
Care should be taken when spraying with either triclopyr
or glyphosate to avoid causing damage to nearby desired
broadleaved plants from spray drift.
Triclopyr will damage broadleaved plants during the
growing and dormant periods; grasses are normally
unaffected and establish quickly after treatment.
Systemic herbicides may be translocated
through the roots to the parent tree or shrub
causing injury.
A permit may be required for an off-label use.
Not surrounded by turf or desired plants, eg
Group N, eg Basta (glufosinate-ammonium) (partially
systemic) is registered for application as a directed
spray for sucker control in blackberry, boysenberry,
loganberry and raspberry plantations. Contact with
non-target plant parts will cause damage.
Seek professional advice.
466 Weeds - Examples of weed situations