Early Harvest And Recent Rain Provide Excellent Weed Control Opportunity

August 2006 - With the harvest a good week to 10 days ahead for most and almost everyone receiving some rain in the past week, growers across the country have the ideal opportunity to get on top of annual grass weeds ahead of drilling this autumn, advises Dr Dave Ellerton of ProCam. Especially so with the hot, dry summer resulting in notably low levels of black-grass seed dormancy.

"For the first time in many years, most people should have both the time and moisture to achieve good stale seedbed weed control," he points out. "The recent rain has been far too limited to replenish soil reserves. But it has largely fallen on standing crops so it should provide sufficient upper soil moisture for a good chit of blackgrass seed, because the soil surface is well-protected from the drying effects of sun and wind.

"The secret of success, though, will be to retain the precious moisture as fully as possible through the primary cultivation and use it to best effect with careful glyphosate applications."

For the best stale seedbed control Dave Ellerton recommends cultivation as soon after harvesting as possible where black-grass and sterile brome are the key targets. With meadow, soft and rye bromes, on the other hand, he advises delaying cultivation for a couple of weeks to encourage dormancy breaking.

In both cases he sees shallow tillage as preferable to ploughing or deeper discing wherever moisture preservation is critical. And he insists good rolling or pressing immediately after cultivation will always pay dividends in optimising weed seed to soil contact as well as moisture preservation.

"By consolidating the ground the same day as cultivating it you'll really preserve its moisture and stimulate the fastest possible weed growth," he stresses. "In fact, I'd be surprised if you didn't get a flush of weeds you can spray-off with Roundup in 7-10 days with the soil temperatures as high as they are."

Under these circumstances and with the extra time available this season, Dave Ellerton strongly suggests many growers should plan on stimulating and spraying-off two flushes of annual weed growth ahead of cereal drilling.

Where annual grass weeds pose particular problems, he stresses that two stale seedbeds before drilling will be infinitely better than one. All the more so given the extent to which the growth of the first germinators can inhibit that of fellow seeds.

"I'd be going in with Roundup Max at 0.75 -1.0 kg/ha as soon as the biggest grass weed reaches the one leaf stage," he says. "The fields will still look brown from a distance, so close inspection is essential.

"This will get rid of the first flush good and early, giving you enough time to tickle-up the soil and get another strong flush of weeds and volunteers comfortably ahead of wheat drilling. Particularly when you only need to leave 6 hours between spraying and cultivation with a modern glyphosate formulation like Max."