Crop watch: Plans needed to tackle this autumn’s high OSR disease risk

Despite some frosts across Lincolnshire, Sean Sparling says soil temperatures are still too high for propyzamide herbicide applications to be effective.

A two-spray strategy is being deployed for phoma and light leaf spot control in western oilseed rape crops, as Antony Wade reports a slow spread of phoma thanks to dry conditions.

Further south, Tod Hunnisett says he’s not concerned about the large size of rapeseed crops as this means tebuconazole can be applied for light leaf spot control without worrying about its growth regulatory effects.

See also: Phoma symptoms reported in oilseed rape crops

In the north, Mary Munro says early drilled wheats are tillering well with cool temperatures helping keep disease in check.

Sean SparlingEast: Sean Sparling

AICC (Lincolnshire)

The first week of November has brought with it the first significant frosts of the season and around 10mm of rain in my part of the world – making things much harder than they needed to be for growers seeking to get the rest of the delayed blackgrass-prone fields drilled.

Frustration over the soggy drilling conditions in what turned out to be a wet and miserable October in Lincolnshire was actually a godsend to those agronomists amongst us who were fighting to hold back the drills on the worst land early in October.

We know that the later wheat gets drilled, the better in these fields. Conditions are still difficult enough for spring cropping to be the only real option now.

If there are bad blackgrass fields that don’t get drilled next spring, at least you stand a chance of still being in pocket at harvest with just the area payment – more than you can expect if they go in badly and pre-emergence herbicides can’t do their job on blackgrass.

Most wheat and barley fields have gone in well on the worst sites and pre-emergence stacks have gone on in good time and in good conditions.

Despite this, blackgrass is emerging with the wheat in some fields and difficult decisions on what to do next are imminent – namely whether to apply Atlantis (iodosulfuron + mesosulfuron) or glyphosate.

Oilseed rape diseases have set off with phoma easily found and light leaf spot less so. Fungicide choice should always cover both, and as we only have protectant activity on light leaf spot, with cooler temperatures it’s development is slowing, so this fungicide application should carry us to spring.

It is still plenty warm enough here for propyzamide (8C and falling at 30cm recommended, we have 11.6C and static).

You can lose well over 10% of the blackgrass control if you put propyzamide on in conditions that are too warm, so why compromise the control when that’s its purpose?

We need 100% from propyzamide, so waiting until soil conditions are cold enough is the best approach.

Antony-WadeWest: Antony Wade

AICC (Herefordshire/Shropshire)

Generally crops have established well despite one of the driest Octobers in the last 10 years that I have recorded.

We had under an inch of rain, but it has been just enough to keep crops growing after a wetter than average September.

The dry weather and good seed-beds have reduced slug risk with only the odd patch or field requiring pelleting twice.

The change in the weather to a cold northerly flow in recent days with the first decent frosts will further reduce the slug activity, but also crops will slow down, so vigilance is required.

While good seed-beds have helped the efficacy of the residual herbicides, the drier than average conditions haven’t.

Where there is a significant flush of brome and wild oats, even after a robust pre-emergence programme on some farms, I am deploying some Broadway Star (florasulam + pyroxsulam) along with some more residual.

Winter barley crops have enjoyed the recent weather and are starting to tiller after some minor chlorosis from the early herbicide needing to be front-loaded for grassweed control.

Winter oats that weren’t sprayed pre-emergence will get a herbicide soon, with Absolute (diflufenican + flupyrsulfuron) used on an Extension of Authorisation for Minor Use (EAMU) being the main choice from the two leaf stage.

The majority of oilseed rape crops have romped away, quite a few having green area indices over 3.0.

The dry month has meant the phoma has developed only slowly and large leaves pose less risk of forming stem cankers.

They have had a fungicide with plant growth regulator activity, as this is the priority at this stage, with light leaf spot the focus for a later spray, possibly in combination with propyzamide applications where required.

However, the autumn has come with its drawbacks as I have found more club root patches in a number of fields.

There is very little that can be done within the crop, although we will try to encourage rooting in the hope that plants will recover.

It may require a rethink on rotations or more widespread use of club root resistant varieties.

Tod-HunnisetSouth: Tod Hunnisett

AICC (Sussex)

What a difference a year makes. This time last year, any work that hadn’t been done wasn’t going to get done. The rain had set in and wheels weren’t turning. I also hadn’t yet lit my woodburner.

This year, not only has everything that was scheduled been completed, but extra cropping has gone in where spring crops were initially planned. The down side of the dry autumn is that some residual herbicides haven’t worked as well as hoped, but at least we’ve had the opportunity for a follow up.

I lit the woodburner three weeks ago and, at the time of writing, we’ve had at least three frosts. Maize has been harvested without leaving a mudbath.

After last year, everyone is very keen to put an aphicide on cereals to avoid the barley yellow dwarf virus (BYDV) problems we saw.

While it would be daft to ignore last year, as I have said, we are in a completely different season. If I’m going through a crop with a follow-up herbicide and the timing is appropriate, then it’s also having a pyrethroid.

I have a lot of wheat that has been drilled significantly later than last year, nearly all having had an insecticide seed treatment, so I’m certainly not going to panic if the weather breaks now and we can’t get on it.

The weather over the next two months is what will make the difference. As it was, I had significant barley yellow dwarf virus (BYDV) symptoms in April-drilled spring oats last harvest.

Oilseed rape is generally looking in good health and some growers are worried that it’s getting too big. I’m not. As far as I’m concerned, a big oilseed rape crop is a nice problem to have.

What it does mean is that if light leaf spot comes in, I can put a big fat dose of tebuconazole on without worrying how much growth regulatory effect it has.

Mary MunroNorth: Mary Munro

AICC/Strutt & Parker (Perthshire)

The prolonged period of dry weather has provided excellent conditions for drilling wheat and fields sown after beans and potatoes are now coming through.

The earliest sown wheats have tillered well already and there is little disease to mention – small amounts of septoria and traces of mildew, but cold night temperatures have prevented these from becoming a worry.

Even slug damage is minimal. Growers have kept up to speed with herbicide applications, too. I have tried some Quirinus (BASF’s new flufenacet + picolinafen product) this season and it will be interesting to see how its persistence and weed suppression compares with Liberator (diflufenican + flufenacet) in field conditions.

Oilseed rape crops are well established this year and good ground cover is essential for holding back the onslaught of pigeons later in the winter.

They are quick to target bare patches to start a feeding frenzy. Proline (prothioconazole) has been my product of choice for autumn light leaf spot prevention.

It is cheering to see a potential lift in the price of malting barley, thanks to increasing demand for whisky. This market has been stuck in the doldrums in recent years and the margin for growers has been miniscule.

It is such an important crop for Scotland, yet paradoxically Scotch whisky does not necessarily have to be made from Scottish grain.

The Scottish government announced the first of its interest-free loans (or part-payments) of the Basic Payment Scheme 2016 through the National Basic Support Scheme.

On the face of it, this is very laudable and should ensure all the applicants who took up the scheme get 80% of their dues in good time.

The inference, though, is that the computer system is still not functioning adequately and the remaining 20% could well be delayed till June 2017.

The cross-border claimants seem to get put into a “too difficult” pile and were among the last to receive 2015 payments.

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