The tool that puts a handle on soil pathogens

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Photo of Rob Long

Growers and agronomists use the PreDicta® B DNA test to identify disease risk before planting and also to monitor disease levels over many years to gauge how effective their rotations are at reducing disease risk

Information gives power: the greatest value of PreDicta® B testing is when there are multiple disease issues. Testing allows diseases to be ranked in order of importance and allows advisers to prioritise management options for the greatest disease issue.
Agronomists Rob Long (B&W Rural and Crown Analytical Services, Moree) and James Miller (Penagcon, Bellata) in northern NSW also see PreDicta® B test results as a powerful tool to test practices. “If you don’t know where your disease levels are, you’re flying blind,” Rob Long says. “Testing helps us to make sure the system doesn’t get out of whack.”

Mr Long recalls how in 2014 he and a grower client were forced to grow the Clearfield variety Elmore CL Plus to deal with imazapic residues after the dry summer: “As it is a susceptible variety, the numbers of root lesion nematodes (Pratylenchus thornei) went through the roof. One poor crop choice undid five years of work in reducing numbers and we will do everything in our power to avoid planting such a susceptible variety again.

“But without the PreDicta® B test we just wouldn’t have understood the impact that one crop could have.”

Bellata grower James Miller says PreDicta® B has enabled him to stay on top of pathogens with regular testing. “It is quick and accurate and covers a massive suite of pathogens,” he says.

He is looking forward to the new test results for Ascochyta rabiei and Phytophthora, particularly given the wetter winter and spring in 2016. “We know from the last wet year in 2010 that their numbers will be up, and this will give us an excellent reference point to keep an eye on them over the coming years.’

For Kaniva, Victoria, grower Alwyn Dyer, growing durum wheat successfully allows him to access a price premium, but durum does not tolerate crown rot so he will not risk planting durum if the PreDicta® B test shows high disease levels.

With consultant Simon Mock of Clovercrest Consulting, Nhill, Victoria, he has been testing regularly before cereals and was surprised to see pre-season results for 2017 crown rot were at an all-time low. The poor season in 2015 meant less cereal stubble was carried over and the excellent conditions in 2016 allowed for good dense break crops that maximised the opportunity for stubble breakdown, reducing the carryover of crown rot. PreDicta® B has given them a better understanding of how the whole system
is working.

In Western Australia, Frank Boetel, a senior agronomist with Farmanco Management Consultants at Katanning, says he has been monitoring the same 60 paddocks over several years and can clearly see where he needs to change management options. He has watched root lesion nematode (P. neglectus and P. quasitereoides) numbers increase in recent years in continuous cereal/canola rotations in the Great Southern and south coastal districts of WA.

With significant yield losses in cereals, growers are now being advised to consider resistant lupins as a break crop instead of the susceptible canola. As a prolific user of PreDicta® B, Mr Boetel is also advising his clients on other options to reduce nematode numbers, including choosing cereal varieties that are less susceptible and controlling early weeds at the season break.

Note: PreDicta® B is a registered trademark of Bayer.

GRDC Research Codes DAS00137, DAV00128

More information:

Dr Alan McKay,
08 8303 9375,
alan.mckay@sa.gov.au;
PreDicta® B