Protect potato performance this spring with Crusade

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A flexible drift retardant, specifically designed for use with blight fungicides, could play an important role in keeping potatoes disease free this spring, according to adjuvant and biostimulant experts, Interagro.

Keeping late blight out of potatoes is a season long campaign for growers and one that seems to be getting tougher as the years go by. With resistance to fluazinam and a regular shift in blight populations, a robust resistance management strategy which improves coverage is essential to safeguard crops and chemistry, believes Stuart Sutherland, technical manager at Interagro.

Stuart Sutherland

Stuart Sutherland

“Keeping spray intervals tight is a practice that growers have become familiar with, but it isn’t without its challenges when unfavourable conditions mean spray days are few and far between.

“Drift is the biggest cause of off-target chemical movement and increases the threat to the crop from late blight where it’s not adequately protected.”

What’s more, strong and weak fungicide actives can have weak spots due to poor coverage, and such weak spots in haulm protection are more likely to be found out, he adds.

But while full crop coverage is vital to prevent scattered infection, the “umbrella-like” structure of the plant canopy – a series of interlocking leaves – makes this very difficult to achieve. “Leaves are good collectors of vertical moving spray in the upper canopy but leaves and stems lower down can be very hard to reach – moving the risk of tuber blight to the whole crop,” warns Stuart.

So what’s the solution?

Developed to help tackle the practical problems growers face, Crusade – from Interagro – is a flexible drift retardant specifically designed for use with all potato blight fungicides to reduce drift and maximise coverage to all parts of the crop canopy.

“Crusade has been specially designed to maximise the performance of blight fungicides in potatoes, by increasing the proportion of spray droplets in the optimum size category for drift reduction and target leaf retention,” explains Stuart. “Research in the field has continually proven that adding Crusade to fungicide sprays helps to maximise coverage to all parts of the canopy, preventing scattered infection and ensuring maximum protection to the whole crop.”

In practical terms, Crusade reduces the fine droplets prone to drift, and optimises droplet size in the upper end of the spectrum that enable the spray droplets to penetrate the canopy lower down and be retained. “To get the best out of blight protection chemistry, droplets cannot be too big – because they’ll bounce off the leaf and miss the target – or too small, which could mean they may evaporate and drift off-target. They have to be just right.

“Crusade creates droplets more capable of reaching the upper and lower canopy and significantly reduces the number of fine spray droplets, smaller than 100 microns, that are the most susceptible to drift.

“With Crusade, the spray angle (usually 110 degrees) is more closely maintained, improving application, helping to ensure the correct dose is applied to the target. The addition of Crusade to fungicide sprays therefore helps to optimise coverage to all parts of the crop canopy, preventing scattered infection and ensuring maximum protection to the whole crop.”

With a flexible application timing and no growth stage cut-off, Crusade can be used throughout the blight control programme with a wide range of fungicides to help maximise blight control.

With an extremely low application rate per hectare, Crusade also offers easy handling for spray operators and avoids delayed drying on the leaf, adds Stuart. “We recommend using Crusade at 0.25% of total spray volume. It’s compatible with all common plant protection products and foliar feeds added to the tank-mix, but we do suggest adding Crusade to the spray tank first, before incorporating anything else.

View from the field

As the dry spell continues to pour over the UK, the pressure is slightly off for potato growers in terms of blight.

John Sarup

John Sarup

However, with unpredictable seasons becoming the “new normal”, having a robust strategy in place is key, should the tables turn, says John Sarup of Spud Agronomy.

“Blight is an interesting one as no one really knows what each year is going to bring – though you can almost always guarantee some form of blight pressure across the growing season,” he says. “At the moment (as of 6th May), we’re not even thinking about blight sprays because it’s so dry. But that could change very quickly.”

When, the time comes to start blight control, John says he will be teaming his treatments with Crusade – an anti-drift agent that helps to remove the barriers that stop blight fungicides performing to their true potential.

“Crusade certainly brings something to the party in terms of how it helps products reach the full canopy.  I started using it two years ago and I’ve found that when you use a fungicide on its own, it’s not the same product as when it’s used with Crusade. There is a noticeable reduction in drift and better protection to all parts of the crop canopy.”

“If you can add something to a product to maximise its efficacy, then it’s a no brainer to me.”

With proven benefits when used with blight sprays, Crusade will be a significant tool in the armoury this year, says John. “Crusade is the one for me. It’s a fantastic product that really helps to maximise product performance.”

As many soils across the country turn to dust as a result of the prolonged dry spell, there may be the temptation by growers to reduce blight spray applications or extend the window between applications, but this could prove to be a detrimental move, concludes Stuart “With the high UV intensity and rapid growth we are experiencing, lush forward crops will need protecting to keep blight out, particularly where humid conditions may become in-dispersed with a sprinkling of rain. It’s not uncommon for small areas of infection to remain hidden until late into the growing season or, worse still, develop when in cold stores.”


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