30 August 2002

Think about sowing later to hit blackgrass

CEREAL growers with blackgrass-infested land need to consider sowing later than usual this autumn to get the best from herbicide programmes.

Thats the warning from BASF after the inclement summer which has reduced opportunities for good stale seed-bed control.

Last autumn, blackgrass seeds germinated in a tight flush, says the firms Rob Gladwin. That gave growers a good chance to remove much of the problem and ease the task of subsequent herbicides through cultivations and pre-drilling glyphosate.

"This summers cold, wet weather when the seed was maturing means much of it is more dormant than usual," says Mr Gladwin. "Shed seed isnt germinating despite ideal conditions."

That means the weed will emerge over a much longer period than usual, limiting the scope for pre-drilling control and strengthening the need for a residual element in post-sowing herbicide programmes.

Last season where blackgrass was troublesome Mr Gladwins advice was to delay sowing until after Sept 15. "This year it looks as though we are going to have to move this line in the sand to late September.

"Its going to take a lot of nerve to hold off. But failure to delay sowing could mean the problem will only get worse.

"Ideally growers need to prioritise their fields according to the potential blackgrass problem and drill the worst last."

Farms using min-till techniques need to be particularly careful, says Mr Gladwin. But neither is ploughing the complete answer.

"If you go the ploughing route, remember that you may still have to deal with germinating seeds ploughed up from previous year. And bear in mind that if this years seed is brought back up next year you will merely have postponed the problem."

This autumns protracted germination will make it harder to time contact-acting herbicides accurately. "It means there will have to be much greater reliance on residuals," he concludes. &#42

BEATINGBLACKGRASS

&#8226 Seed more dormant than usual.

&#8226 Extended germination period.

&#8226 Fewer pre-sowing control chances.

&#8226 Delay drilling where possible.