Crops have Competitive Edge – CPM – Dick Neale

Weed control

As a relatively dry and kind winter morphs into spring, CPM asks agronomists from across the UK how weed control is likely to differ this season.
By Phil Garnham

The challenges of the past two miserable autumns meant that the battle against weeds was almost lost before it had begun.

The biblical rainfall caused many to drill late, some weren’t able to get any autumn herbicides on and all too soon blackgrass was visible as far as the eye could see.

This year has been very different. A mild autumn presented an opportunity to create a decent seedbed, get drilling done early, put on pre-emergence sprays and drill before January.

So, does this mean we won’t have so much to worry about this year? When it comes to agronomy, nothing is ever straightforward, says Dick Neale, technical manager of Hutchinsons.

“This year is a completely different Situation and farmers should be prepared for a very different scenario compared with recent years. Expect to see more crop competition. There’s much better crop establishment and we’re seeing hedge-to-hedge cropping compared with last year, when crop cover was quite sporadic.”

That said, Dick believes it’ll be important to keep an eye on the headlands this year, where the density of the plant population could well be an issue, giving weeds the space to grow.

Blackgrass stragglers

“In some situations, the top 5-10cm is being over-worked due to the min-till systems that many are using. This can create waterlogging and give weeds an opportunity to gain a foothold. It would be so easy to walk straight into the middle of the field and think everything is fine and miss a potential problem,” he says.

When asked about the old foe, blackgrass, Dick says when looking at the tail-end stragglers of blackgrass in the crop, it’s tempting to think enough money has already been spent on residual herbicide usage this year.

“Most growers have applied at least two applications of residual herbicide in the autumn, with some considering another application in the spring,” he says.

“With the wheat price at £200/t, it’s a good opportunity to get on top of blackgrass, especially as this hasn’t always been possible for the past couple of years. This season the crop will help finance it,” he suggests.

Thanks to an absence of delayed drilling and a very robust crop with good ground cover, Dick believes we’re unlikely to see the late February/early March emergence of blackgrass seen in recent years.

The thick crop will blank out the sunlight, stopping it from reaching the soil surface, which is what triggers the germination of blackgrass and other weeds, says Dick Neale.

 

Nitrogen effects

Fertiliser application is another point to consider, says Dick. “The other thing that triggers weed germination is the early application of the large amounts of nitrogen. Due to the price of it and because of the way crops look at the moment, I think growers will perhaps be reluctant to spend too much money on early nitrogen and that will temper the amount of weed seed germination.

Cleavers, in particular, may be notable for their reduced numbers.” Luke Wheeler, agronomist with Indigro and a director of the AICC is, like many, just grateful for a more normal year.

“The seedbeds we’ve achieved this autumn have been pretty good and, nine times out of ten, we’ve gone back with pre-em sprays and residual herbicides, so in most cases everything is up to date.”

Luke’s message is one of caution, however, suggesting it’d be prudent not to feel too relaxed about weed control.

“At this time of year, it’s still probably a little too early to tell what impact pre-em residual herbicides have had. The fact it’s been so mild means the residual chemistry will have broken down quite quickly, but it probably hasn’t fully broken down yet.

“So we’re now at the point where we’ll start to see weed growth push through. Where there were high blackgrass numbers last year, expect to see emergence now, especially with the sometime mild winter weather we’ve had.”

Luke agrees crops look pretty good on the whole, but he always says to clients that, from a blackgrass point of view, it doesn’t mean anything yet.

“I’m sure this mild weather will affect the residual products and we’ll get a flush of growth where residual chemistry has broken down.”

Despite his concerns over the kind autumn/winter, the pros most definitely outweigh the cons, he believes. “Overall, there’s a lot to be said for having a decent seedbed and managing to get on with spraying in reasonable weather conditions, using good water volumes. It’s great just getting
the basics done because for the past two years, we haven’t been able to even do that.”

Luke highlights last year, where it wasn’t possible to get back to top up the pre-em programme, as a warning.