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Tackling the increased take-all risk in wheat
How can growers minimise the impact of the soil-borne pathogen take-all, as visible symptoms in current crops hint at increased risk for consecutive cereals drilled this autumn?
The level of take-all inoculum has been high this year, with symptoms starting to show in crops after a dry spell leading into the harvest period.
This is leading to a warning about the potential for primary infection this autumn in second and third wheats, and growers are advised to invest in a seed treatment to protect yield.
Ideal conditions
Take-all is a soil-borne fungus that e ects the roots of second and consecutive cereal crops, but it takes a certain set of conditions over the growing period to be met to see the most striking symptoms.
Over the past 12 months, these parameters have been met, with a mild and wet winter allowing the disease to get a foothold in crops.
A relatively dry spring followed, and, in many years, this would be enough to reduce disease progression, but capped soils have helped to retain moisture in the root zone on more bodied soils.
In turn, this has led to signi cant secondary spread of the disease from roots infected in the autumn to new roots produced in the spring, damaging their ability to supply water and nutrients to above ground biomass.
Now, with hot and dry weather prevailing, distinct patches of a ected plants are visible in second and third cereals, with stunted plants and ‘white heads’, where ears are empty of any grain – the tell-tale sign of take-all damage.
Nutrient struggles
One agronomist that has seen takeall symptoms in commercial crops is Syed Shah, southern regional agronomist with NIAB, and he expects the disease to impact on nal yields.
“It’s been worse on lighter, drier soils and where early nitrogen wasn’t applied, with the take-all e ect on rooting meaning that plants struggle to get the nutrients they need,” Mr Shah explains.
In his area across Sussex, ProCam’s crop production manager Mike Thornton (pictured) hasn’t seen signi cant take-all symptoms himself, but ProCam colleagues have shared images of its impact on wheat crops elsewhere in the country.
He says it has been worse in wetter parts, where rooting may have been lazy or compromised by compaction.
“Then, when the dry time arrived from April onwards and the water table dropped, problems started to become evident.
“When plants aren’t taking up nitrogen, they drop tillers and the remaining ones produce poor grains and we’ll start see its true impact when the combines make a start,” says Mr Thornton.
soils and where early nitrogen wasn’t applied, with the take-all e ect on rooting Mike Thornton (pictured)
However, Dr Shah says some of his clients are considering planting more second or third wheat crops given on grassweed control in the previous wheat crop,
Rotational options
Mr Thornton reckons that after some rotational disruption over recent seasons, growers across his area are increasing their oilseed rape area to break long runs of cereal crops. However, Dr Shah says some of his clients are considering planting more second or third wheat crops given the relatively strong wheat price and the crop o ering relatively consistent results. Much will depend on grassweed control in the previous wheat crop, but with new chemistry in Luximo (cynmethalin) giving an edge over ufenacet against blackgrass, it may o er further encouragement when considering consecutive cereals.
“Last year, second wheats outyielded rst wheats in many cases due to the crop being drilled later and su ering less disease.
“Even if you achieve 7.5t/ha with a second or third wheat, it will still pay for itself given the strong grain price,” he explains.
In these situations, crops will be vulnerable to take-all and he says Latitude (silthiofam) and phosphite-based seed treatment to encourage rooting are two things he recommends as a matter of course in most situations.
“There is nothing you can do about take-all later in the season, so why would you compromise the crop by not using Latitude?” says Dr Shah.
Mr Thornton agrees and says although the right variety choice can help a crop withstand the e ects of take-all and is an important piece of an integrated control strategy, the genetics still need support.
Latitude will reduce primary infection that can spread and create the patchy symptoms that characterise the disease.
“If you opt for a second or third wheat, I will say use Latitude. I can’t see a reason why you wouldn’t because it’s a disease that can halve yield.
“If you are going to grow and invest in these crops, you should do it properly and get things right from the start. There is no going back afterwards,” he adds.
Nutrition key
Dr Shah says higher seed rates, drilling into a good quality seedbed and consolidating after drilling is key in second or third wheats, along with
...from previous page early nutrition, both in the autumn and the spring. and the spring.
Where phosphate soil indices Where phosphate soil indices are lower than 2.5+, he advocates are lower than 2.5+, he advocates applying 50–60kg/ha applying 50–60kg/ha of P2O5 fertiliser to fertiliser to the seedbed prior the seedbed prior to drilling. At 2.5+ to drilling. At 2.5+ and above, then any and above, then any fresh phosphate can fresh phosphate can wait until the spring. wait until the spring.
It can then be It can then be combined with rst combined with rst nitrogen applications in nitrogen applications in the form of di-ammonium the form of di-ammonium phosphate just ahead of phosphate just ahead of when crops start to grow in when crops start to grow in the early spring. the early spring.
“I always recommend an early “I always recommend an early application of 50–60kg/ha of N in application of 50–60kg/ha of N in second or third wheats too. second or third wheats too.
“There is little point in waiting “There is little point in waiting until the crop is actively growing, until the crop is actively growing, particularly if using urea. The risk particularly if using urea. The risk of leaching is very low, and it takes of leaching is very low, and it takes 10–14 days before it becomes 10–14 days before it becomes available to plant, so get it on so available to plant, so get it on so it’s there when the plant needs it,” it’s there when the plant needs it,” explains Dr Shah. explains Dr Shah.
Latitude cost bene t calculator
Given the high levels of inoculum seen this autumn, the investment in Latitude is justi ed, as a return Latitude is justi ed, as a return on investment is highly likely given the potential likely given the potential yield loss and high grain price.
Certis Belchim’s Cost Bene t Calculator online tool is a good way of seeing that ROI in black and white, with growers entering the cost growers entering the cost of Latitude from their supplier, target seed rate and expected grain price.
It will then show a margin over Latitude cost in a moderate take-all risk situation, which the rm’s Tim Eaton (pictured) says is favourable, even in years where the grain price is closer to £150/t. closer to £150/t. “In addition to the “In addition to the protection against take-all, protection against take-all, we’ve also seen that plants we’ve also seen that plants make much better use of nitrogen inputs when treated with Latitude, reducing the potential for leaching. “It’s an economic and environmental win-win,” environmental win-win,” he adds. he adds. The calculator can be found at www.certiseurope.co.uk/cropfocus/latitude#c6127 FG
Take-all: How it a ects susceptible cereal crops
• Second or consecutive cereals drilled early in mid- to late-September are most susceptible to primary infection, as the take-all fungus is more active in the soil • As root growth kicks o in spring, take-all jumps from older infected roots to new ones, moving through the crop to form ‘patches’ of infection • Roots become black and brittle, compromising water and nutrient uptake, stunting growth, and reducing or stopping grain development altogether • Cultural controls such as rotation, later drilling, ne and rm seedbeds all reduce risk. Any products that promote rooting and root health can help, such as phosphite seed dressings and foliar sprays • Just one fungicide seed treatment exists that has true activity on the take-all fungus, with Latitude (silthiofam) reducing primary infection in the autumn and protecting yield.
CONSISTENT AND HIGH-QUALITY
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