East: Delay drilling for better blackgrass control

With September now behind us, the swallows have all gone and so it all begins again –  I refer of course to the futile pursuit of trying to stop some growers drilling wheat too early in their bad blackgrass fields. With only 21 mm of rain so far in September here, stale seed-beds with good flushes of blackgrass  have been the stuff of dreams. Aye – there’s the rub, because with October now upon us and with most other jobs now complete,  thoughts and itchy trigger fingers are turning to drilling “while it’s still dry and before the rain comes”.

On non-blackgrass and the more benevolent soil types, I’m all in favour of drilling wheat, rye and barley now – “make hay while the sun shines” as they say.  The only problem with “making hay while the sun shines” is that if you drill winter wheat into seed-beds that are full of blackgrass that will come up when the wheat does, “making hay while the sun shines” is exactly what you will be doing with the wheat next June! Holding your nerve and getting at least one more good flush of blackgrass out of the way with glyphosate before you start drilling may well be the difference between harvesting your wheat and silaging it.

Flufenacet will form the base of my pre-emergence herbicide strategy alongside diflufenican and prosulfocarb. Tri-allate will then follow. The critical thing is to use stacked combinations of effective pre-emergence herbicides at the pre-emergence timing – within 3 days of drilling the crop. Putting a layer of flufenacet, diflufenican and prosulfocarb in that top inch or so where the black grass seeds are trying to germinate, will kill far more than applying it 7-10 days after drilling when the roots of that blackgrass will already be below – and growing away from – any herbicide subsequently applied. Use glyphosate pre-drilling, drill, roll & spray – all within 3 days for best results, make sure you create fine, firm seed-beds and apply early post-drilling applications of stacked herbicides – you can’t do much more than that.

Mind you, with wheat worth £100/t, saving £100/ha on herbicides by drilling the worst fields with spring barley, spring wheat or another spring crop might be the only way to save money – we can’t cut back on nitrogen we can’t cut back on fungicides, but by cutting back on drilling them in the autumn and not committing yourself to an expensive full programme, you may be able to save some money on herbicides – just a thought!

TSW’s vary widely from variety to variety once again this season, so check before you drill, and keep those seed rates up where blackgrass will be an issue, because the effects of crop competition on its control should not be underestimated – as a certain supermarket says, “every little helps”. The fact still remains though, that on those really bad blackgrass fields, are you really doing the right thing drilling them with winter wheat in the first week of October? Judging by the last three seasons, I  would suggest that the sensible answer to that question is a very loud “NO”.

As  far as oilseed rape goes, it’s been a mixed bag so far this season, with those crops drilled before the August bank holiday romping away and that drilled since struggling to establish in the hot, dry conditions – it’s easy to find seeds sitting in dust which have yet to consider germinating. Flea beetle damage has most definitely been an issue here – but pyrethroids are still working well and single applications have so far held it in check, allowing crops to establish. However, the main yield damage from flea beetle comes from the larvae in the stem and not from the shot holing, so only time will tell how much good we’ve done.

Mesurol (methiocarb) seed dressing has certainly helped in the early stages and treated areas within fields are easy to see, but even on these fields we have had to treat cabbage stem flea beetle (CSFB) in the early stages. But as pests go this autumn, the slugs are proving to be the biggest issue and despite the tinder dry conditions, they are causing significant damage in some areas – heavy dews are probably aiding their cause. Remember that slugs don’t tunnel through the soil like worms do – they rely upon you leaving spaces between clods in loose and uneven seed-beds, so the more open and the less consolidated you leave fields after the drill, the more likely you are to suffer problems from slugs.

This is borne out in the OSR crops, where those plonked in with the subsoiler are proving far more troublesome than those drilled or put into more even, firm and consolidated seed-beds. Disease levels remain relatively low in OSR, although the first signs of phoma and light leaf spot are beginning to appear, so fungicides will start to go on over the next 10 days.

The other cause for concern is the rapid increase in aphid numbers over the last couple of weeks – both OSR and cereals will need watching very closely this autumn….here we go again then!


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