Maximise performance to tackle new blight strains

Maximise performance to tackle new blight strains

For the third consecutive year independent blight field trials have shown the performance of REVUS has been maximised with the addition of Crusade drift retardant technology.

Syngenta potato marketing manager, Mark Britton, highlighted the addition of Crusade in the tank mix with REVUS has shown to reduce the risk of drift and therefore improve spray deposition throughout the crop canopy.

He reported that, for the first time, the Eurofins trials in 2020 were physically inoculated with the more aggressive blight strain 36_A2, along with Pink 6, Blue 13 and Green 37 – representing a broad spectrum of the most common UK blight isolates.

Mr Britton pointed out the season-long single product treatment protocol used in the Syngenta trials at Eurofins, involving 11 applications in 2020, was designed to better assess the true intrinsic activity of fungicides, compared to using them in a programme where individual strengths or weaknesses could be masked. It would also better flag up any potential issues of changing product performance to shifting blight populations from season to season.

“Results from 2020 confirmed no concerns with the efficacy of REVUS against all the blight strains in the test, including 36_A2 which increased as a percentage of the general late blight population from 2019,” he said. “Furthermore, when used in combination with Crusade it again consistently achieved better results.

In untreated plots blight infection started to take hold towards the end of July, and developed very quickly to complete destruction of the green leaf by the third week of August. All the blight fungicides performed well up until early September, when differences clearly started to become apparent.

“Under the trial’s artificially intense blight pressure, of the fungicides that were tested, the REVUS + Crusade was the stand-out result for keeping blight at the lowest level in the trial plots,” advised Mr Britton.

With the nozzles used for the Eurofins trials being quite drifty, it is believed the addition of Crusade is helping to get more fungicide into the canopy and working more effectively.

Using an assessment of AUDPC (Area Under the Disease Progression Curve) gives the best picture of season-long product performance, where REVUS + Crusade clearly showed the lowest infection of all the products on trial. That very much confirmed the results seen in the intrinsic activity trial run in 2019, added Mr Britton.

3D Ninety keeps application on target

The Eurofins trials in 2020 also demonstrated results of REVUS applied through the drift reduction nozzle technology of the new Syngenta 3D Ninety was still further enhanced with the inclusion of Crusade, albeit by a lesser amount than with more drifty conventional potato nozzles.  

Syngenta New Farming Technologies Lead, Harry Fordham, reported the 3D Ninety nozzle’s 55° angle has shown to get more even blight protection spray distribution throughout the crop canopy.

3D90 Nozzle
Syngenta
30 July 2020

“The inherent drift reduction from the design of the 3D Ninety minimises any impact of sideways spray movement, to achieve consistent distribution across the boom. Whilst the nozzle produces a spray pattern less affected by boom height – to give better distribution through the potato crop canopy,” he advised.

“Used for REVUS application in conjunction with Crusade, it proved to give the best and most reliable results in nozzle trials at Eurofins last season.”

Mr Fordham highlighted the team had used glow-in-the-dark UV tracer dye to reveal precisely where application droplets were reaching in the Eurofins trials.

“Results showed that with a standard potato nozzle, for example, producing mostly fine droplets with low kinetic energy, the majority of the product is held on the growing point and top leaves of the canopy.

“When the Crusade drift retardant is added, we get more larger droplets, which are better able to reach down to the middle and bottom leaves of the canopy. The coverage and retention on the upper leaves is still very good, but there’s additional benefit down to the lower leaves.

“Analysis of the droplet spectrum has shown that the Crusade takes out the really small and most drift susceptible fine droplets, so it’s making the nozzle less drifty and ensuring we get more product on the crop.”

With the 3D Ninety, Mr Fordham showed applying REVUS alone the nozzle provided far more consistent coverage of product deeper into the crop canopy and evenly across top and middle leaves.

“When the Crusade was added into the mix, the coverage on the leaf surface is further enhanced, but also with more product getting down to the lower leaves.”

Translated into results in the field with the blight fungicide trials, it showed all the nozzles performed better with the Crusade in mix with REVUS. The greatest improvements were seen from the more drifty nozzles, such as the flat fan and standard potato nozzle, but even with the new drift reduction technology there were still valuable additional benefits from its inclusion.

Mr Fordham added the 3D Ninety, fitted to alternate the spray pattern forwards and rearwards along the spray boom, improves efficacy, increases work rate to take advantage of any spray opportunities and reduces drift – which is good for the environment and getting the best value from every application.

“With the Syngenta Potato Nozzle being withdrawn from manufacture, the 3D Ninety will be the nozzle of choice for potato applications when it is launched later this year,” he advocated.

The recommended water volume of 200 l/ha for both pre-emergence applications and blight sprays remains best practice in most situations, including treatments with Crusade on the blight spray mix.

Download a copy of our Crusade product guide here for trials results and further information on the benefits of Crusade.