The wheat book : principles and practice - Department of Agriculture ...

CHAPTER 12 – WEED CONTROL IN WHEAT THE WHEAT BOOK
INTEGRATED WEED MANAGEMENT
No one weed control method is normally sufficient by
itself for an effective weed control program at reasonable
cost. Instead, a combination of agronomic, biological and
chemical methods will usually be found to be the most
efficient and cost-effective. In recent years there has been a
trend towards over-reliance on the use of selective
herbicides for weed control at the expense of traditional
cultural methods. The widespread onset of herbicide
resistance has meant that selective control of annual
ryegrass, wild oats and wild radish in wheat is now difficult
for many farms and a whole farm integrated approach is
necessary. For the wheat crop a number of options are
available which can be employed to minimise the effects of
weeds in the wheat crop.
burning stubble and header trials to reduce weed seeds
on the surface,
light autumn cultivation to ensure even weed
germination,
non selective herbicides such as paraquat applied after
seeding and just prior to crop emergence where the
weeds have already germinated,
Using knockdown rates of herbicides or cultivation
treatments which kill all weeds prior to seeding,
delayed sowing to ensure more weeds emerge prior to
seeding,
increased seeding rate (yield losses from weeds are
minimised with sowing rates above 100kg/ha),
closer row spacing (e.g. 3” . 7cm, broadcast) to ensure
less space for weeds and more competition,
placement of fertiliser below the seed or between twin
rows of crop so that weeds are further from the
nutrient,
choosing varieties with the best agronomic adaptation
to the paddock so they are more vigorous (e.g. more
disease tolerant varieties) and competitive with weeds,
ensuring insect management and plant nutrition is
optimal so as to maximise early growth and
competition,
selective herbicides, especially in combinations or
sequences which allow for maximum control of
resistant weeds, and
hand rogueing of plants, especially wild radish.
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