Second wheat performance could well suffer to an even greater extent than last year, warns Rob Plaice of Monsanto Crop Protection following analysis of this season’s initial NIAB take-all root assessments at HGCA Recommended List trial sites across the country.
The GS31 assessments from seven of the eight RL second wheat sites reveal an average Take-all Index of 7.4 on the 1-100 scale in a range of varieties receiving no take-all active seed treatment. Two sites are already showing infection levels of more than 10%.
This is slightly higher than the average 7.0 Index recorded at the sane growth stage in 2010 (when only one site showed infection levels above 10%) despite the noticeably colder early winter and markedly drier spring across the main arable area of the country.
"In the absence of take-all seed treatment, average RL second wheat control yields were a record 3.7 t/ha below those of the same varieties grown as first wheats at just 6.83 t/ha last year," Rob Plaice points out. "Despite one of the lowest pre-harvest levels of take-all infection in recent years, the dry spring and early summer clearly meant crops were especially vulnerable to even relatively moderate levels of root damage.
"With England receiving less than half the March and April rainfall of 2010 in total and East Anglia barely a quarter – just 31.2 mm and 12.1 mm on average, respectively – this season is placing even more stress on root systems. So with a similar pattern of take-all build-up we can expect to see untreated yields suffering even more than they did last harvest.
"Unless crops are buoyed up by a major deluge in June, that is. In which case, the experience of 2008 and 2009 shows we are likely to see a major surge in infection levels in the run-up to harvest."
This season’s monitoring again underlines the vital importance of getting second wheats off to the best possible start in the autumn, with effective take-all protection regardless of sowing date and inoculum carry over. Particularly so since the bulk of the RL crops were sown in mid to late October, beyond what is generally assumed to be the time of peak autumn infection risk.
"The past two years have really emphasised how much better well-established crops are able to cope with the stresses of a dry spring," Rob Plaice observes. "With second wheats at such a disadvantage to first wheats in establishment – all the more so when the winter comes in so early – anything that can be done to enhance their early root development will really pay dividends in bolstering performance.
"In this context, the latest carefully controlled NIAB trials showing highly significant increases in both plant biomass and tillering in addition to major reductions in take-all infection across a range of leading varieties from treatment with the specialist take-all seed dressing, Latitude (silthiofam) are especially welcome.
"They show that the value of the treatment in promoting overall crop establishment as much as in combating early take-all development."
