Persistence pays to keep out blight
The rainfastness and persistence of Revus is creating significant advantages in blight control during a difficult year, according to early in-season results of trials at the Les Barges Blight Research Station in Switzerland.
In trials where blight infection in untreated plots hit 100% on 18 June, the Revus treatment programme had still effectively kept blight out of the crop. At the same time, blight which started to appear around the 13 June in plots treated with fluopicolide + propamocarb had reached at least 28% infection in 10 days. Benthiavalicarb + mancozeb and cyazofamid included in the trial had also seen blight levels building to between 5 and 10%.
Researchers highlight heavy and frequent rainfall through the end of May and early June, combined with heavy disease pressure from local early potato production, had subjected the crop to intense blight infection. Throughout the trials Revus had performed consistently well.
Syngenta Potato Manager, Tom Whitworth, adds that after last year's experience, many UK growers have heeded the BPC advice to stick to seven day intervals for blight fungicides this season. "But with the continued periods of heavy rain the trials have shown how the efficacy of less rainfast products can be severely weakened, and leave the crop dangerously exposed to infection at the end of an application interval," he warns.
"If application has then been delayed by wet weather or the time taken to get around a large acreage, there is a real risk that blight may be able to get into the crop. At times like this the persistence of Revus will help to ensure that crops still retain effective protection from blight attacks at the end of a spray interval."
Furthermore, there are reports that growers may be seeking to stretch spray application timing to reduce costs and the number of applications made over the course of the season. "If application is being delayed to 10 days or more, when growers perceive the risk of blight to be low, it is imperative that they use a persistent product such as Revus to offer protection if blight conducive weather raises the risk."
Mr Whitworth adds that using modern blight fungicides such as Revus can actually reduce the environmental impact of growing a potato crop and more than offset the frequency of a seven-day application programme. Being such an inherently powerful blight fungicide, requiring only a low level of active ingredient to give excellent results, means Revus has an Environmental Impact Quotient (EIQ) rating of just 3, compared to over 20 with some older mancozeb-containing blight fungicides, for example.
"Replacing four mancozeb-based blight applications with Revus could reduce the overall EIQ score by more than 80, which is well within the targets set for growers by retail customers," he adds.
