Australia
May 16, 2013
Root lesion nematodes (RLN) may be costing northern region graingrowers up to $500 per hectare in lost yield across a range of common wheat varieties.
That’s the message from Richard Daniel, Northern Grower Alliance (NGA) chief executive officer who is involved in Grains Research and Development Corporation (GRDC)-funded ground-truthing research into the disease in collaboration with Department of Primary Industries Queensland (DAFF) and NSW Department of Primary Industries (NSW DPI) plant pathologists.
Root lesion nematodes (RLN) are a costly problem for northern region graingrowers producing key wheat varieties
“Rising populations of the nematode species Pratylenchus thornei (Pt) can significantly reduce yield and economic returns in Pt intolerant wheat varieties and wheat variety selection is a critical tool for growers,” Mr Daniel said.
“Trials conducted near Yallaroi, NSW in 2012 showed this nematode reduced the leaf area index, crop biomass, yield, grain quality and nitrogen recovery in wheat, and also is increasing the severity of crown rot.”
He said apart from the economic impact in 2012, wheat variety choice also has a flow on effect in the ‘disease level’ left behind.
Wheat variety choice resulted in up to a 10-fold difference in final Pt population levels and planting two successive years of ‘very susceptible’ varieties resulted in a 10-20 fold increase in final Pt population figures compared to two moderately resistant selections.
“Variety choice is critical for minimising yield losses in the year of production but also just as important in managing the disease threat level for subsequent crops,” Mr Daniel said.
There was no apparent yield impact in a range of either canola or faba bean varieties. Chickpea yields were more variable at this site, however overall there was a concerning reduction in yield across a range of key chickpea varieties by ~15-20pc or 0.35-0.4 tonne/ha at an economic cost of $175-200/ha.
“Pt is a major constraint in the northern cropping region, not only due to the large potential impact on yield, but also its broad geographic distribution,” Mr Daniel said.
“Successful management involves practices including on-farm hygiene and soil testing to identify problem paddocks, however crop and variety choice are likely to be the major tools used for management.
“The most important step though is to test your soil and know what level of disease threat you actually face.”
The 2013 Wheat Varieties Guide is now available and can be downloaded from http://www.grdc.com.au/Research-and-Development/National-Variety-Trials/Crop-Variety-Guides#Queensland.
To download the NGA research paper including data and analysis, visit http://www.grdc.com.au/Research-and-Development/GRDC-Update-Papers/2013/02/Rootlesion-nematode-management-the-cost-of-getting-it-wrong.
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