Archive Article: 1998/01/17

17 January 1998




Wondering if that surviving blackgrass could be resistant? Gilly Johnson reports on a new quick test that claims to offer an almost instant answer.

THE RACE to provide a rapid, commercial test for blackgrass resistance hots up with a prototype system launched this month from Novartis.

The QuickTest offers a definitive answer to resistance within three to four weeks, claims the company. The fastest turnaround from the current alternative – the blackgrass seed test – is an October result from seed gathered in summer.

One crucial advantage of the QuickTest compared with the blackgrass seed test is the fact it can be used at any point when the blackgrass emerges in autumn. It tests whole plants, not just seeds, and uses plant samples taken at any time between the two-three leaf stage and ear emergence. So growers who suspect they have a problem would not have to wait until summer, when blackgrass forms seed heads, in order to check out weed populations.

"The results are consistent at any growth stage. And because it allows the testing of blackgrass in the autumn and winter, growers would then be able to adjust herbicide programmes to suit," says Novartis Andy Pigott.

The QuickTest can check for all types of resistance, including target site – the fop and dim resistance; enhanced metabolism – the IPU type resistance; and cross resistances between different products. It could be performed before or after herbicide application. A wide number of grass weed species suit this testing system, but the initial focus is to be on blackgrass and wild oats.

The logistics and mechanics of plant collection will be worked out during this seasons trial run. For a basic single product resistance test, 30 plants are required; for target site resistance, 45 plants, and for cross-resistance against three products, 60 plants are needed. These have to arrive at the Cambridge testing site in good condition, preferably within a week of collection.

Certain distributors in resistance hotspots such as Lincs, Cambs and Essex will be offering it this season, but only on a limited basis.

Full launch is anticipated next autumn. Eventual cost to growers has yet to be decided, but Mr Pigott suggests that it will work out cheaper than the current alternative – the seed test, which costs about £70 to £100/sample.

He predicts that the QuickTest could ultimately be used by growers as a DIY windowsill test.

Mr Pigott is keeping mum on the detail of exactly how the test works; Novartis has applied for a world-wide patent on the methodology, which was devised in Switzerland. But he is confident that the QuickTest is the best answer yet – "and we have looked at a number of different solutions".

Resistance guru Dr Steve Moss of IACR-Rothamsted gives a cautious welcome. "Anything that helps growers assess resistance is a good idea, but it would have to prove itself as working reliably in practice, and thats not always easy. Even with the seed test, samples have to be of good quality in order to give a worthwhile, meaningful result – the same would apply here. I look forward to hearing more about how this test works."

Dr Moss and his team at IACR-Rothamsted are developing a fast turnaround seed test, using petrie dish assay techniques. The aim is to produce resistance results by September, in time for growers planning autumn herbicide programmes. The test is scheduled for a trial run this summer, and is under close scrutiny by AgrEvo, with a view to commercial development.

Elsewhere in Europe, rapid tests for blackgrass resistance are also being sought. French scientists at the Instutut National de la Recherche Agronomique (INRA) are proposing three solutions: a 48-hour tiller technique, a more time-consuming pollen test and a seedling test.


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