By Kellie Penfold
In the past few years, southern NSW farmers have been starting to look for alternatives to canola following continually unexplained falling yields.
But a cooperative approach between grain research organisations and growers is solving many mysteries surrounding the impact of disease.
Between the Best Bet Canola Management Project and Grenfell Greenthorpe Cropping Group Project, both funded by FarmLink Canola Plus, supported by the GRDC and the Graingrowers Association, the impact of blackleg and sclerotinia are being fully assessed and guidelines for their control established.
Peter Hamblin, managing director of Agritech Crop Research at Young in NSW, is one of the researchers overseeing the field trials at Galong and Wallendbeen (started in 2001 by Best Bet), Grenfell and Greenthorpe (started in 2002) and Ardlethan, Dirnaseer - between Temora and Junee - and Lockhart (established under the FarmLink banner).
"In Southern NSW concern has been growing that canola yields in the high rainfall area of 550 to 600 millimetres annually have declined since 1998," Mr Hamblin says.
"Growers were throwing their hands in the air and many were seriously questioning the viability of growing canola. If it wasn"t such an important part of their rotation and if legumes were worth more it could have been out the door."
Farmers, researchers and advisers established a priority list of yield impact factors, and disease is at the top.
"It has already been established canola will yield to its water-limited potential when blackleg and sclerotinia are controlled or absent," Mr Hamblin says. "The trials in the drier areas of southern NSW - Lockhart, Dirnaseer and Ardlethan - have already surprised many, showing disease is a bigger issue than first thought and you don"t need high rainfall for them to impact on yield potential."
Each site has three sowing dates and two varieties with fungicide treatments to control blackleg and foliar fungicide sprays for sclerotinia control. At this stage the trials will continue for another two seasons.
In-depth research into blackleg has led to a set of recommendations for its control. The best economic responses are delivered by the use of Jockey® as a seed dressing and Impact®, which is applied with fertiliser at sowing.
"While Jockey® is the cheaper treatment alternative at around $6 per hectare, for those who have the potential to gain greater yield by controlling blackleg, Impact® at $20/ha is worth looking at," Mr Hamblin says. "Growers at Wallendbeen and Galong have already started using Impact® with great results. The decision will come down to variety, blackleg rating, blackleg risk and cost."
The problem with fully assessing the impact of sclerotinia has been dry seasons. "We really need a wet winter and spring to properly assess the treatment this year and then another good wet year to establish theories as facts."
In 2001, sclerotinia in the trials was controlled by up to three applications of fungicide. Researchers admit this is cost prohibitive onfarm and now have to establish where growers get the "best bang for their buck".
For more information:
Peter Hamblin, Agritech Crop Research, Young, 02 6382 6711, firstname.lastname@example.org
Kirrily Condon, FarmLink Canola Plus, email@example.com
GRDC Research Codes: AGN 2, FLR 00001, program 2