Australia
September 6, 2007
 Diseases
continue to pose serious problems for maize growers in the wet
tropics and this year Polysora or Tropical rust and Banded leaf
and sheath rot have been major concerns.
However, new varieties developed with
Grains Research and Development
Corporation (GRDC)-support show strong resistance to both
diseases.
Queensland Department of Primary Industries and Fisheries
(QDPI&F) researcher Ian Martin said 2005-06 summer trials of new
hybrids with resistance to Polysora rust were promising despite
yields being severely reduced by Cyclone Larry.
“The Kairi research site was harvestable but yields were well
down on what we were expecting prior to the cyclone,” Mr Martin
said.
Despite the setback, results identified hybrid 2143 as combining
effective rust resistance with a grain yield of 36 per cent more
than the newly-released hybrid AT1.
“Hybrid 2143 is scheduled for release under the name AT2 for the
2007-08 maize season in limited seed quantities,” Mr Martin
said.
“Hybrid 2143 yielded 1.2 tonnes per hectare more than hybrid AT1
and its rust rating of 2 means that rust was confined to the
very lowest leaves.”
Mr Martin said this was a vast improvement on QX6, released six
years ago, which had rust infection on 75pc of its leaves and
QX8, released four years ago, which had rust on about 40pc of
its leaves.
Banded leaf and sheath rot caused by Rhizoctonia solani, has
been very much in evidence this year, probably due to a very wet
February.
Hybrids in the current Atherton trial site ranged from zero to
23.7pc of plants infected. Infection rate of AT2 was 5.3pc which
was less than half the Rhizoctonia infection rate of AT1. AT2
also had very strong resistance to Polysora rust. |
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