Time fungicides to keep canopies disease-free

Protecting sugar beet crop canopies from disease will be key to helping backward crops make the most of late-season sunshine and build yield.

A prolonged beet drilling campaign brought on by the late winter means many crops are up to a month behind where they would be in a typical year had growers been able to complete sowing earlier. Ensuring canopies are kept free of disease so they are able to fully utilise the solar radiation through the autumn will be key to helping crops build yield.

Bayer technical manager for Norfolk, Jack Hill (pictured), says application timing and the interval between the first and second sprays will be key to maintaining clean canopies. 

“The results of nearly 10 years of trials indicates that crops do best when fungicides are applied at the first signs of disease. This is typically in July so monitor crops closely and follow BBRO bulletins as disease will be reported as soon as it is found.”

Rust remains the principal disease concern and the recent run of warm weather is likely to have created favourable conditions for disease sporulation. This is similar to 2016 and 2017, but crops were generally better established. Nonetheless, some growers were caught out in these years and struggled to give the crops the protection they needed as a result.

“The lesson of the past two years is to apply the first fungicide at full-label rate as soon as disease is detected, maintain water rates of at least 200-litres/ha to ensure canopy penetration and follow up with a second fungicide, also at the full-label rate, around 28 days later to give crops the protection they need,” says Mr Hill. 

Physiological boost

The physiological benefits of fungicides, in particular Escolta (cyproconazole + trifloxystrobin) with its strobilurin component has been found to give crops an added boost. Maintaining clean and active canopies will support photosynthesis through until lifting and give crops the opportunity to keep building yield. This is likely to be vital to crop performance this season, believes Mr Hill. 

“Trials demonstrate that crops which receive two full-rate applications of Escolta consistently out-yield those receiving other treatments because they fare better heading into the winter,” he says.

In 2017 Bayer trials found that the second application of Escolta at 0.35-litres/ha added 12t/ha over untreated to December-lifted crops, and almost 26t/ha to February-lifted crops. There was high rust pressure through the summer of 2017 and this put greater pressure on the second spray. Opting for a single application or selecting less effective chemistry didn’t give the necessary disease protection.

“Across all lifting dates the average yield response in 2017 for crops receiving two full applications of Escolta was 14.9t/ha, this is worth £335/ha with beet at £22.50/t,” he adds.