17 September 1999


IRISH farmers have a notable first on offer to them this autumn, a take-all control product that promises to revolutionise many farms crop rotations.

The product is Latitude (proposed active name silthiopham) and manufacturer Monsanto staged its lavish global launch in Dublin last month. But despite the global banner, only Ireland has the seed-treatment available this autumn.

Judging by one Co Dublin growers response, uptake will be widespread. "It will make a huge improvement to growers like us," says Jim Bergin. He grows 260ha (600 acres) of cereals, potatoes and vegetables at Bally Boughal, near Swords, north of Dublin.

Second and even third cereals have to be grown, so that the potato rotation is sustainable. But wheat in that situation is hard-hit by take-all on the limey, heavy soil.

"It can take up to 3t/ha in yield. In the last three years we have gone away from second and third wheats because of the disease," he says.

Gross margins

Oats and barley are grown instead, and whilst these crops are hit by take-all too, the impact is less severe. Nonetheless, gross margins fall far short of first wheats.

Monsantos trials show an average yield response of 1t/ha (0.4t/acre) in high take-all risk wheats, (see table) and 0.48t/ha in moderate risk crops. Both situations merit the Latitude treatment, says the firms field development manager for fungicides, David Leaper.

"But it is not really appropriate in a low risk crop. First wheats dont get the same level of primary infection that second cereals do, so there is little to be gained from treating them," he suggests.

Mr Bergin is not so sure. The seed treatment delays the onset of the disease, which makes earlier drilling possible – about two weeks earlier according to Monsanto. That spreads the workload, and in turn reduces the seed rate necessary, cutting both seed and fuel costs.

"We can sow twice as fast, so use half the amount of diesel," he comments.

Lower seed rates also aid disease control culturally. Plants are further apart so transfer of the fungus from one plants root system to the next is less likely. "There is quite a lot growers can do to cut take-all culturally," says Dr Leaper.

That point is stressed by Monsanto, who says the product is a tool to take-all management, and not a complete control in itself. Cultural measures should still be taken, especially as take-all incidence is very variable, depending on the season.

Delaying drilling, ensuring the seedbed is firm and not manganese deficient, and avoiding liming on second cereals will all reduce the build up and consequent yield impact of the disease. Extra, and more frequent, spring nitrogen helps plants compensate for diseased roots.

Mr Bergin believes Latitude will be widely used, not least on his own farm where oats and barley will be replaced with second wheats. "I can see us using it right across the board, even on first wheats if it allows us to drill a bit earlier," he concludes. &#42

Take-all risk assessment

Check previous cropping to establish a risk profile. A = wheat or barley,

B = rye, oats, triticale, grass, set-aside, C = broad-leaved break.

2 Yrs Ago Previous Crop Risk Ave Yield Response t/ha

B/A A High 1.0

C A Moderate 0.48

A B Moderate 0.48

C/B B Low 0.25

A C Low 0.25

C/B C Zero Nil

NB: Yield responses based on average of 5 years work, 170 trials.

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