18 February 2000

Maximise crops, minimise weeds

CAREFUL attention to spring barley management and especially herbicide use can help maximise the crops potential and minimise weed problems elsewhere in the rotation, say a Dorset farmer and his consultant.

Dorset arable farmer John Tory has long battled with wild oats on his 295ha (434-acre) cereal enterprise at Turnworth Farm, near Blandford. The clay cap with flints over chalk suits high yielding, good quality spring and winter malting barley. But pockets of heavy wild oat infestation are a worry.

In an attempt to cut the overall herbicide cost and minimise the risk of herbicide resistant wild oats Mr Tory now incorporates Avadex (tri-allate) into the herbicide programme, followed by CMPP + dicamba as a cheap and cheerful follow up for stubborn weeds.

"Our spring cereal herbicide programme cost us around £29.50/ha to control wild oats, broadleaved weeds and meadow grass," says Mr Tory. "We could use Grasp (tralkoxydim) followed by Quantum (tribenuron-methyl) and a hormone mix in two applications, but this would cost around £36/ha for complete control of the same set of weeds."

Early control before the crop canopy thickens is vital, says adviser Peter Gould for agchem distributor UAP. Later applications can kill the top of the wild oats, but still allow late tillers to emerge, which may require a second application. "Post-emergence Avadex takes away that risk and provides some residual activity."

Drilling at Turnworth Farm is with a 4m Rau Accord cultivator combination and starts in January or early February. "The key is to get the right soil conditions," says arable assistant Marcus Foice.

Optic goes in at a target rate of 400 seeds/sq m, with the lighter land rolled at the first opportunity and heavier land rolled at the two-leaf stage. Avadex is applied immediately after drilling with the farms TMA 4 applicator to avoid any contractor delays.

Maltster demand for higher grain nitrogen may mean nitrogen use is upped from 125-130kg/ha to 150-160kg/ha. "With a liquid system 160kg/ha all at once is impractical," says Mr Foice. "So we split it 60kg/ha when tramlines are first visible followed by the 100kg/ha as a top dressing."

Like the herbicide strategy, attention to detail is the key with fungicides, says Mr Gould. "The farm is in a high risk rhynchosporim zone which is extenuated by rainfall of more than 46in a year."

The crop is sprayed before the lesions become visible to the eye with 0.5 litre/ha Colstar (fenpropimorph + flusilazole) and 0.25 litre/ha Amistar (azoxystrobin). A follow-up spray and again with low rate Amistar to give an extra 0.7t/ha (1.7t/acre). &#42

(Left to right) Arable specialist Marcus Foice, UAPs agronomist Peter Gould and farmer John Tory work together to optimise spring barley.