Take-allis rearing its ugly head in many second wheat crops across the country thisseason, with clear differences in both whitehead and root infections levelsrecorded between varieties and seed treatments, according to the latest resultsfrom Monsanto Crop Protections annual tracking studies.
Reflectingthe seasons generally good establishment and growing conditions, root infection levels recorded in untreated crops at GS75are generally lower than the past two years with NIAB analyses showing anaverage Take-all index of 16 on the 0-100 scale.
Even so, study co-ordinator Manda Sansom and her team report a number of badlyaffected crops this season, especially in the Eastern Counties, together withinteresting 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, shenoted. But by GS75 infection levels in Evolution were almost half those inHoratio which Recommended List trials suggest is a much less good second wheat.So it looks like Evolutions superior performance in the slot comes, at leastin 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 infectionsat GS31, from an index of 12 in the JB Diego treated with only a single-purposedressing to just 6 where the take-all specific treatment was added.
This resulted in a highly visible halving of whitehead levels from almost50% to less than 25% recorded at GS70in late June (Figure) underlining theextent to which restricting early take-all infections can carry through tovaluable performance improvements.
Thefact that this was with a reasonable second wheat variety sown in mid-Octoberas a first wheat after barley with a full fungicide and robust nutrientprogramme emphasises how much risk the disease poses and how little can be doneto combat its development after the initial establishment phase, she pointedout.
This seasons studies reinforce the growing understanding of the disease andits development gained through the past 10 years of take-all tracking work. They also suggest there will be plenty oftake-all inoculum about this autumn to challenge wheats and barleys grown assecond cereals.
Specialist take-all seed treatment has become routine for many second wheatgrowers, including those sowing well into October Manda Sansom noted.
This is hardly surprising as our trial work over all the years shows an averagesecond wheat yield benefit of 0.7t/ha from Latitude treatment, together withworthwhile improvements in specific weights. At the same time, weve recordedan average yield response of 0.4 t/ha and valuable grain quality gains fromwinter barley treatment. At a typical cost of less than 25/ha, this isextremely cost-effective, even at current cereal values.