Take-all is rearing its ugly head in many second wheat crops across the country this season, with clear differences in both whitehead and root infections levels recorded between varieties and seed treatments, according to the latest results from Monsanto Crop Protection’s annual tracking studies.

Reflecting the season’s generally good establishment and growing conditions, root infection  levels recorded in untreated crops at GS75 are generally lower than the past two years with NIAB analyses showing an average Take-all index of 16 on the 0-100 scale.

Even so, study co-ordinator Manda Sansom and her team report a number of badly affected crops this season, especially in the Eastern Counties, together with interesting varietal and seed treatment differences in associated trial work.

“Untreated crops of Horatio and Evolution grown side by side in East Yorkshire, for instance, showed the same initial level of root infections at GS31,” she noted. “But by GS75 infection levels in Evolution were almost half those in Horatio which Recommended List trials suggest is a much less good second wheat. So it looks like Evolution’s superior performance in the slot comes, at least in part, from a better ability to grow away from rather than resist infections.

“In complete contrast, the value of the specialist seed dressing silthiofam (Latitude) evident in Dorset trials resulted from a halving of root infections at GS31, from an index of 12 in the JB Diego treated with only a single-purpose dressing to just 6 where the take-all specific treatment was added.

“This resulted in a highly visible halving of whitehead levels – from almost 50% to less than 25% – recorded at  GS70 in late June (Figure) underlining the extent to which restricting early take-all infections can carry through to valuable performance improvements.

“The fact that this was with a reasonable second wheat variety sown in mid-October as a first wheat after barley with a full fungicide and robust nutrient programme emphasises how much risk the disease poses and how little can be done to combat its development after the initial establishment phase,” she pointed out.

This season’s studies reinforce the growing understanding of the disease and its development gained through the past 10 years of take-all tracking work.  They also suggest there will be plenty of take-all inoculum about this autumn to challenge wheats and barleys grown as second cereals.

“Specialist take-all seed treatment has become routine for many second wheat growers, including those sowing well into October” Manda Sansom noted.

“This is hardly surprising as our trial work over all the years shows an average second wheat yield benefit of 0.7t/ha from Latitude treatment, together with worthwhile improvements in specific weights. At the same time, we’ve recorded an average yield response of 0.4 t/ha and valuable grain quality gains from winter barley treatment. At a typical cost of less than £25/ha, this is extremely cost-effective, even at current cereal values.”