[ASC-media] SIGHTS SET ON SUMMER WEEDS
brendon at iinet.net.au
Fri Feb 4 14:58:55 EST 2005
SIGHTS SET ON SUMMER WEEDS
With the 2004-05 harvest in the bin in record time, WA graingrowers are
thinking ahead to the coming season, and, in particular, summer weeds.
Growers spend an average of $40,000 a year on controlling weeds.
According to Grains Research and Development Corporation (GRDC) supported
researcher Abul Hashem of the Department of Agriculture, excessive summer
rainfall and subsequent heavy weed growth can reduce emergence and yield of
subsequent wheat crops.
Summer weeds are opportunistic, emerging during summer fallow with adequate
They grow and utilise water and nutrients from various soil depths,
depending on the rooting depth of the weed species and should be controlled
soon after emergence to minimise loss in the yield and quality of wheat, Dr
A long term WA trial site funded by the GRDC-supported CRC for Australian
Weed Management used irrigation to simulate summer rain.
Non weed controlled plots had 22 per cent lower emergence of wheat plants,
with fewer tillers, 29 per cent lower wheat biomass and 20 per cent lower
The trials also indicated that major summer weeds, caltrope and afghan
melon, may inhibit wheat emergence and growth, probably due to toxic
chemicals released by the weeds.
This can cause fewer tillers or plants and biomass of wheat at the lower
We found summer rainfall and subsequent weed growth also led to reduced
soil nitrogen being made available for subsequent grain crops.
The reduced nitrogen caused poor crop growth, despite the difference in
soil nitrogen being low compared with total crop demand.
Nitrogen may also have been absent during the critical first six to eight
weeks after seeding, Dr Hashem said.
Authorised by GRDC and issued on its behalf by Brendon Cant & Associates,
Tel 08 9385 7779
MEDIA CONTACT: Dr Abul Hashem, Tel 08 9690 2187
Brendon Cant & Associates
Public Relations & Marketing
114 Branksome Gardens
City Beach WA 6015
Tel 08 9385 7779 Fax 08 9385 7776
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