[ASC-media] EARLY SPOTTING LEAVES NO EFFECT: Crop Doctor

BRENDON CANT brendon at iinet.net.au
Wed Jul 25 03:02:28 CEST 2007


EARLY SPOTTING LEAVES NO EFFECT 25.07.07


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Graingrowers should be aware that visual herbicide phytotoxic symptoms in
early crop growth stages do not necessarily lead to reduced yield.

 

Grains Research and Development Corporation (GRDC) supported Department of
Agriculture and Food WA researcher, Dr Harmohinder Dhammu, evaluated the
herbicide tolerance of recently released wheat varieties.

 

He discovered that despite early severe spotting or necrosis on leaves,
there was often no significant negative effect on crop biomass at flowering
stage or grain yield at harvest.

 

In Katanning, two weeks after spraying carfentrazone + MCPA, severe leaf
spotting appeared on all varieties, with a loss of 40 percent of the leaves.

 

However, despite these early visual symptoms, crop yield was not affected. 

 

In contrast, no visual symptoms were observed with this mixture at Merredin,
but significant yield reduction occurred in the varieties Kalka and
Wyalkatchem.

 

Similarly, metsulfuron caused some early plant stunting in all varieties at
Katanning without affecting crop yield, while at Merredin, metsulfuron didn’
t produce any visual symptoms, but yield reduced in most varieties. 

 

Binnu and Bullaring had the most promising results of the GRDC supported
trials, similar to or better than Wyalkatchem, showing good tolerance to
commonly used herbicides.

 

No yield loss was recorded using the herbicide mixture metolachlor + diuron
at Katanning and Merredin.

 

Dr Dhammu also discovered that tank mixing diuron with metolachlor, rather
than applying metolachlor alone, improved crop safety.

 

Mixing these two herbicides also increased the spectrum of weeds controlled.

 

www.grdc.com.au

 


The Crop Doctor is GRDC Managing Director, Peter Reading, Tel 02 6272 5525


Further Information: Dr Harmohinder Dhammu, Tel 08 9690 2217

GRDC REF: CDJuly071.doc/DAW0134/Rainbow

Brendon Cant & Associates
Public Relations & Marketing 
Suite 5
4 Gugeri St
Claremont WA 6010
Tel 08 9384 1122


 

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