September 13, 2012
Yellow Rust and Black – Grass Pressures Make Key Wheat Seed Treatment Vital
Major foliar disease threats and huge black-grass pressures mean many first and second wheats should be treated with a fluquinconazole seed dressing as routine this autumn to reduce the risk of another season of serious disease and weed losses.
This is the firm recommendation of Agrii crop protection technical manager, Chris Bean following the most damaging foliar disease season since 2007 and serious problems with annual grass weeds in many areas.
“The value of reduced rate fluquinconazole (Galmano Silver) seed treatment in improving foliar disease control became crystal clear over the past season,” he reports.
“It kept early yellow rust infections at bay extremely well. This meant growers were able to apply their T0 sprays at the optimum Leaf 4 timing. Which enabled far better T1 timing to protect Leaf 3 – wherever the April weather permitted – and, in turn, also better-timed T2 and T3 sprays.
“In contrast, where yellow rust romped ahead in the mild winter, earlier-than-ideal T0s were compounded by weather-delayed T1s to leave a gap of five weeks or more between treatments in many cases. This allowed Septoria to get an early hold on Leaf 2, seriously compromising crop performance.
“Add the research evidence we also have for significant improvements in early crop competitiveness with grass weeds and fluquinconazole seed treatment becomes especially important for 2013 wheat agronomy.”
Despite far less favourable conditions for disease development in 2011, Agrii trials on yellow rust susceptible wheats under a number of different fungicide regimes showed an average response of 0.48 t/ha from adding fluquinconazole to a standard single-purpose seed treatment.
Three years of trials at the company’s main black-grass management site at Stow Longa have further demonstrated clear value from the treatment in promoting early root and leaf area development in shy-tillering varieties.
Where black-grass was problematic, for instance, the average response to the seed treatment increased to 0.8-1.0 t/ha across a range of varieties as a result of greater crop competitiveness.
“This extra benefit has been especially valuable in a season where serious chemical control limitations have reinforced the need for the greatest possible contribution from cultural controls,” stresses Chris Bean.
“In a generally low disease season like 2010/11 we recorded typical margins over treatment costs of £57-£62/ha from fluquinconazole in rust-susceptible wheats, rising to £95-£100/ha with relatively less competitive varieties where grass-weeds were a problem.
“When all our latest trials data are processed and analysed I have no doubt the benefit to cost ratio of treatment will be very much higher in the 2011/12 crop. That’s why we consider it so important rust susceptible and less competitive varieties are widely treated this autumn.
“Low rates of highly-targeted active ingredients means seed treatments represent great value for money, as well as environmental value,” he adds. “Under the sort of climatic variability we see these days they are, of course, also extremely valuable for being non-weather dependent. And they have the extra benefit of transferring the responsibility for application from grower to seed supplier.
“Overall, seed treatments offer some of the best and most cost-effective agronomic risk insurance available for modern wheat growing. In view of particular pressures from BYDV, slugs and fusarium this season, I’d strongly advise combining Galmano Silver with Redigo Deter (prothioconazole + clothianidin) to secure the most effective seedling establishment and protection against pest and virus damage as well as early disease and black-grass control.