19 July 2002

Thumbs up for blight fungicide

A NEW blight fungicide, tested for the first time on a fenland farm last season, has won the farmers approval for its new mode of action to combat increasingly aggressive blight, ease spray decisions alongside watercourses and deliver reduced rates of active ingredient for supermarkets.

Ranman TwinPack contains new active ingredient cyazofamid, which can be used at the low rate of 80g/ha and, unlike many blight fungicides, has no LERAP restrictions on its use near water.

Late approval meant it was only available in limited quantities last year. But Roger Hunt-Pain of Bridge Farm, Northside, Thorney, Cambs managed to acquire some for field-scale testing. He grows 55ha of mainly pre-pack potatoes on black fen soil for the Solanum packing group.

He decided to include the product in his intensive blight control programme, because it appeared to offer a new mode of action. "Over time blight strains seem to be becoming more aggressive, so the old chemistry is not so good at controlling the disease."

Blight pressure on the farm is increased by a hefty irrigation regime that goes round the potato crop every seven days. An in-field weather station helps monitor local blight risk.

Numerous watercourses are a big headache. "We want to avoid using different products on LERAP headlands and it would add up to a lot of land if we left 6m around every watercourse."

At full canopy his seven-day programme normally switches to a protectant such as Curzate (cymoxanil + mancozeb), but last year four applications of Ranman alternated with Invader (dimethomorph + mancozeb).

Despite two hefty peaks to blight pressure the alternating programme gave good disease control, leaving no sign of the disease, says Mr Hunt-Pain.

Ranman was easy to use and Mr Hunt-Pain liked the low rate of active ingredient. "It is what supermarkets are getting keen on."

He also found the rapid rainfastness of Ranman suited his irrigation, allowing watering to continue later the same day.

&#8226 Another new product that impressed Mr Hunt-Pain in first field use this year was Tanos (cymoxanil + famoxadone). Used earlier in the season it provided good protection, another mode of action and was nice to use, he says. "It pours well and mixes well. Its nice to see these new products coming forward." &#42

Field-scale testing of new blight product Ranman within a programme impressed Cambs grower Peter Hunt-Pain last year.