Improvement in potato blight control

Independent trials have found on average, a 19% improvement in potato blight control, simply by adding a low-cost drift retardant to the fungicide tank mix.

Yields were also improved by an average of 2.2t/ha, which at potato prices of £200/t, equates to £440/ha improvement in margins at an application cost of just a few pounds per hectare.

The specialist drift retardant, Crusade, will be launched to the market this summer by its manufacturer, Interagro.

“The product has been rigorously tested, and its launch follows two years of independent trials conducted by SRUC’s Dr Ruairidh Bain, as well as in-field studies by Eurofins, Agrii and a range of fungicide manufacturers, including market-leader BASF,” explains Emma Ralph from Interagro.

Emma Ralph.

Dr Bain described the launch as “exciting” for the potato industry, because products like these don’t increase the amount of fungicide being applied, rather they provide the industry with a valuable ICM option.

The Crusade trials were conducted in 2014 and 2016 as part of Dr Bain’s highly regarded potato blight research and carried out as part of SRUC’s extensive field trials at Scottish sites.

These two seasons were very different according to Dr Bain, with epidemiology developing fairly gradually in 2014, whilst in 2016 potato crops were challenged early, with blight present in the crop as soon as the Crusade-including sprays were started.

“We studied Crusade tank-mixed with six different fungicides, four SCs and two WGs. When Crusade at 0.5 l/ha was added to Percos the results were really quite outstanding,” he explains. “For five out of the six fungicides, there were statistically significant improvements, the sixth showed a positive trend.

“What’s most interesting is the consistent positive responses with all of the fungicides we have trialled. We already know that adjuvants can make a real difference to fungicide performance, but most are fungicide specific, whilst Crusade gives the flexibility both in terms of product compatibility and timing,” he notes.

Interagro’s Emma Ralph is equally excited about Crusade and reports that other independent trials wholly concur with Dr Bain’s findings.

“Crusade has been developed to minimise drift and support full coverage and optimum dose of fungicide to all parts of the crop which we know is so vital to protect against blight. By reducing the number of fine droplets prone to drift and helping the fungicide to spread after application, we get better coverage to the full haulm with improved penetration into the crop”.

“Field observations and grower experience confirm that Crusade also cuts drying times for partner fungicides, which brings real practical advantages, namely enabling growers to continue spraying in showery conditions,” she explains. “The trials and extensive use on-farm in 2016 also demonstrated impeccable crop safety, even with Shirlan, known to cause phytotoxicity when mixed with mineral oil.

“With current blight strains producing sporangia earlier and in greater numbers than older strains, maximum coverage with fungicide is crucial. Where coverage is not optimal there tends to be scattered infection across the crop, which moves the risk of tuber infection to the whole crop.

“Growers understand the principles of effective blight control – the right fungicide choice, at sufficient dose, applied at tight intervals – but we all know that sometimes things don’t go to plan and spray programmes are compromised,” she adds.

In terms of product compatibilities, Crusade has improved blight control with all partner fungicides – including Hubble, Percos, Presidium, Electis, Shinkon and Shirlan in the trials concluded, as well as a range of other partner fungicides in commercial field programmes.

“Of key benefit to growers is the flexibility Crusade provides. As well as the wide tank mix flexibility and low dose rate, there is no maximum growth stage cut-off and Crusade can be used throughout the blight fungicide programme,” she notes.

Crusade can be used on all potato crops at a dose rate of 0.25% v/v. At a water volume of 200 l/ha this equates to 0.5 l/ha. At water volumes of 300 l/ha, the application rate is 0.75 l/ha.

Interagro recommends that Crusade is added to the water in the sprayer tank before any other products.

Crusade is available to purchase now from Agrii.