Long-lasting protection and curative blight action

New potato fungicide chemistry will offer growers long-lasting protection against blight combined with a degree of curative control, according to manufacturer Certis.

Valbon, containing blight active benthiavalicarb-isopropyl plus mancozeb, will be targeted for use after the rapid canopy growth stage up until the crop begins to senesce to make the best use of its characteristics, the firm’s Peter Shakespeare says.

Its primary strength is its excellent protectant properties.

“It prevents spores that land on the crop from germinating, and reduces the formation of new spores.”

Protection is extremely long-lasting.

“It is very persistent on the leaf surface.

In trials it gave up to 19 days’ persistence, although obviously we wouldn’t recommend leaving that [interval between sprays].”

Indeed the usual 7-10 day interval between applications will apply.

“For anti-resistance reasons we will also be recommending no more than six sprays in the season, and no more than three in a row.”

Full label rate will be 1.6kg/ha.

Valbon’s curative activity – it will take out latent infections of up to 24 hours – will also interest growers.

“Curative activity is improved by adding a specific adjuvant we have in development.”

The firm hopes the adjuvant will be registered in time for use next season.

Extremely rainfast, the product also penetrates the leaf and locally re-distributes within plant tissues to protect new growth, which will be important if it is used during the rapid development stage, he notes.

But Valbon is not particularly suitable for use at the end of the season when preventing tuber blight was important.

“It has activity on zoospore germination, but only limited activity on zoospore movement, so if you get zoospores it would be better to switch to another product with activity on zoospore motility,” he admits.

Zoospores are responsible for tuber blight infections.

Commercially available in Belgium, The Netherlands, Switzerland and Austria last season, Valbon will be available for the first time in the UK this season.