Western Australia
May 14, 2008
Source:
GRDC's The Crop Doctor
Weed resistance to herbicides is
part of the spectrum of challenges facing today’s graingrowers.
The good news is that
GRDC
supports many projects in this
area in order to manage resistance and develop effective
strategies for weed management.
Recent GRDC-supported research by Drs Abul Hashem, Catherine
Borger and Shahab Pathan of the
Department of Agriculture
and Food WA (DAFWA) indicates that brome grass, Bromus
diandrus, is becoming a resistant weed.
Dr Hashem said 2007 glasshouse experiments at DAFWA’s Merredin
Dryland Research Station showed brome grass had multiple
resistance to Group B and C herbicides.
Seeds that survived an application of herbicide were collected
from roadside plants at a site west of Beverley. Plants grown
from the seed were in the ‘resistant’ plant group and were
compared with a control or ‘susceptible’ plant group.
At the label rate of 210 grams of active ingredient per hectare
of Group C herbicide, metribuzin, less than two per cent of the
susceptible population survived, compared with 85 per cent of
the resistant brome grass population.
At the label rate for the Group B herbicide, sulfosulfuron, 85 -
94 per cent of the resistant brome grass survived, while only 2
- 10 per cent of the susceptible population survived.
When treated at the label rate of imazapic plus imazapyr (Group
B herbicides) 83 per cent of the resistant population survived,
while five per cent of the susceptible population survived.
Dr Hashem indicated that brome grass, currently a minor weed
species, could quickly invade cropping areas, potentially
causing serious losses in grain yield if control failure occurs
due to resistance development.
Dr Borger recommended growers, where possible, should implement
integrated weed management practices, including using the full
spectrum of herbicides available with different modes of action.
Physical practices, such as using a chaff-cart, burning header
row, using green and brown manuring, delaying sowing and
occasionally using full-cut cultivation to reduce weed density,
were also control options.
www.grdc.com.au/weedlinks
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The Crop Doctor is
GRDC Managing Director,
Peter Reading |
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