Stringent sampling needed to assess crown rot risk
Growers in the northern region are urged to use correct sampling techniques if they are to accurately assess the risk of the cereal plant disease crown rot in the lead up to this cropping season.
This is particularly relevant leading into the 2015 season with the high durum wheat grain price last year likely to influence many growers to consider a switch to durum this year.
Durum is highly susceptible to crown rot so the cost of sowing into a high disease risk paddock is likely to be significant.
NSW DPI senior plant pathologist Dr Steven Simpfendorfer said greater accuracy in crown rot disease assessment testing would pave the way for growers to better plan their crop and varietal selection prior to winter crop sowing and avoid yield losses.
He added that the use of the DNA based soil testing services prior to sowing was showing potential in identifying crown rot in the northern region, but required a stringent sampling strategy.
“In recent years, use of the DNA based soil testing service PreDicta B® has proved a reliable indicator of nematode populations but question marks have been raised by industry over its accuracy in assessing crown rot risk within the northern region,” Dr Simpfendorfer said.
“The challenge centres on whether a soil-based test can reliably detect the presence of a stubble-borne pathogen.
“PreDicta B® is a good technique for identifying the level of risk for crown rot and other soil-borne pathogens prior to sowing within paddocks but requires a dedicated sampling strategy and is not a simple add-on to a soil nutrition test.
“The important message for industry is - if you are not willing to follow the recommended PreDicta B® sampling strategies then do not assess disease risk levels prior to sowing.”
Research funded by the Grains Research and Development Corporation (GRDC) and conducted by the South Australian Research and Development Institute (SARDI) and the NSW Department of Primary Industries (DPI) is helping boost the accuracy of the PreDicta B® test by fine tuning soil sampling techniques and recommendations.
Recent results have highlighted that adding short pieces of stubble from the base of cereal plants (‘spiking’) significantly improves the detection of the Fusarium species that cause crown rot. A further national survey also determined that all Fusarium species known to cause crown rot are being detected by the current PreDicta B® tests.
Crown rot is widespread in wheat, barley and durum paddocks in central and northern NSW and southern Queensland. Symptoms include discolouration (honey brown) of the crown, lower leaf sheaths and tiller bases and whiteheads.
Caption: NSW DPI senior plant pathologist Dr Steven Simpfendorfer says following the recommended PreDicta B® sampling strategies is the only way to accurately assess the level of risk for crown rot prior to sowing.
Dr Steven Simpfendorfer, Senior Plant Pathologist
NSW DPI, Tamworth
02 6763 1261, 0439 581 672
Michael Thomson, Senior Consultant, Cox Inall Communications
07 4927 0805, 0408 819 666
GRDC Project Code DAS00137; DAN00175