Second wheats performed better than expected in last year’s RL trials. But despite generally low average take-all infection levels and the advantage of much-needed late season rainfall, control yields were still the third lowest in recent years, reveals the 2011 Latitude national take-all monitoring study.

The root assessment study, undertaken by NIAB and Monsanto at all HGCA Recommended List second wheat trial sites across the country, recorded an average late season Take All Index of 25 on the 1-100 scale.

This was almost identical to the level recorded in 2010. However, at 9.1 t/ha average second wheat yields were noticeably higher than the modern year low of just 7.0 t/ha recorded the previous year. Combined with poorer than normal first wheat control yields at 10.1 t/ha this brought the RL second wheat control yield gap back down to the 1 t/ha level of 2008.

“Interestingly, in 2008 our monitoring showed a record average Take All Index of 64,” noted

study co-ordinator, Rob Plaice of Monsanto Crop Protection. “So we definitely seem to be seeing higher yield penalties from the disease these days.

“The very much drier springs and early summers we’ve been getting of late have clearly been putting far greater pressure on root systems – especially where they are compromised by take-all  – limiting spring nitrogen uptake and encouraging early senescence.

“Thankfully, last season’s late summer rain enabled slightly later maturing second wheats to recover rather better than most first wheats. So the yield gap was restricted to just a tonne. I dread to think what would have happened had the weather stayed dry for a further two weeks!”

 While the late rain proved a saviour for many wheat crops – although sadly not for most on light land – Rob Plaice warns that it will also have led to a greater carry over of take-all inoculum to this autumn’s plantings; especially where second wheats were drilled in September.

Under these circumstances, he congratulates growers on the extent to which they are taking-up the second wheat improvement challenge by employing a take-all specific seed dressing as well as choosing varieties that perform relatively well in the slot.

“The latest research shows that more than three quarters of growers are using specialist Latitude (silthiofam) treatment as standard on their second wheats this season, progressively switching from more general fluquinconazole dressings.

“This is important because we know from our RL site monitoring that even crops planted well into October can see significant levels of infection and damage without the protection of an effective take-all seed dressing. And, with the increasingly unpredictable nature of the growing season, any damage to root system is likely to have a far greater impact on yields than in the past.

“In addition to major reductions in take-all infection, of course, carefully controlled NIAB trials also show the additional benefit of highly significant increases in both plant biomass and tillering from Latitude treatment.”