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Grant Reid

Crop agronomy insights for this April in Scotland

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Grant Reid assesses the latest agronomic challenges for Scottish growers

Crop Progress

There was some progress with ploughing, although at the time of writing in mid-March a lot of stubble still remains. By this time last year, sowing was underway, but bar a couple of brave chaps up in the Black Isle I hadn’t heard of anyone managing to start by that point.

Some fertiliser had been applied, where you could travel and in general crops were starting to grow away and looking okay. The early stages of stem extension had started in oilseed rape, while the last odd fields of potatoes were still being lifted – not always with any positive results.

Grant’s agronomy tips for April

1. Prioritise workloads

As the weather continues to play havoc with spring crop drilling, fertiliser spreading and spraying, and any other jobs to do on the farm, some careful planning will be needed through April to keep on track.

Consider what needs to be done and when, in what order, and what impact that might have on other jobs. For example, do you need to roll fields if you didn’t in the autumn, to instigate a bit of tillering? Does it also need a herbicide? In that case make sure you are giving the crop enough time to semi-recover before hitting with a herbicide.

Where herbicides haven’t been applied, they will be one priority to consider, especially if it is difficult grassweeds. Typically brome is the key weed, which Pacifica® Plus (mesosulfuron + iodosulfuron + amidosulfuron) is good against, as well as a super spread of broadleaf weeds.

Remember Pacifica Plus is purely contact acting so consider whether all the weeds have now emerged, and also whether the weed is still in the label growth stage for control – although that shouldn’t be a huge issue this year.

With condensed workloads it will be tempting to put weed control in with T0 sprays, but ideally I would try to spray herbicides as a standalone so you don’t stress the crop even more. If you do need to tank mix, then consider whether your selected partners are supported.

2. Check for yellow rust

T0 sprays might be something that ultimately doesn’t happen on too many farms in Scotland with the amount of other jobs to do. It will be a case of weighing up the risks – for example varietal resistance and drilling date.

At T0 the main diseases to worry about are yellow rust and mildew. Assess crops, speak to your agronomist, and decide whether it needs treating. If it is heaving with disease then obviously that might need spraying, but if it is not too bad and / or variety ratings are favourable you might be able to not spray anything until T1.

3. Think about fungicide budgets

While I suspect most T1 fungicides in wheat will end up being in May, except possibly in the southern parts of Scotland on advanced crops, it’s worth starting to think about what you might spend on these crops this year.

That’s not going to be a straightforward decision given how backward some crops are looking and the stress they have been under. Equally it will depend on disease pressure and it’s not always a straightforward lower potential equals lower spend equation, as lower potential doesn’t necessarily mean lower disease pressure.

Good value products though will likely be important, and while I know you will think he would say that wouldn’t he, Ascra® (bixafen + prothioconazole + fluopyram) really does fit that description.

It’s worked well in trials virtually matching more expensively priced products for yield from two spray programmes at T1 and T2, it covers all the main diseases and is a one-can solution.

If you want to spend a little more because disease pressure is higher, then our new product Vimoy® (isoflucypram) will be available. It will be sold in co-packs with various prothioconazole formulations primarily, such as Proline® (prothioconazole). You can’t buy Vimoy as a straight by itself.

Vimoy + Proline matches Revystar® (mefentrifluconazole + fluxapyroxad) on Septoria, and although it is slightly behind Univoq® (fenpicoxamid + prothioconazole) most growers will opt to use that product at T2. Vimoy is also active against both strains of true eyespot and provides excellent greening benefits, making it a very good, albeit at a premium to Ascra® , option at T1.

4. Rapid growth in winter barley could impact timing

Once the weather improves and winter barley crops take up nitrogen it’s easy to foresee crops rocketing through growth stages, which could make T1 timing a little trickier.

Ideally you’re aiming for GS30/31, when controlling disease will help limit any tiller abortion by the plant and therefore maintain yield, which is set by maximising the number of viable tillers.

Both Ascra® and Siltra® (bixafen + fluopyram + prothioconazole) are good all-round fungicides, and will help control Rhynchosporium, brown rust and net blotch. Ascra is the stronger product and would be a good choice at T1 in many cases, although the one Ascra spray could be saved for T2 if Ramularia is thought to be the major concern.

5. Disease control now required on oilseed rape

A lot of oilseed rape crops probably won’t have had a spray for light leaf spot in the autumn or since Christmas given the weather. Light leaf spot won’t have waited though, and so a spray as soon as possible either at stem extension or early flowering is going to be a priority early in April.

Once the crop is flowering, Sclerotinia also becomes a risk and I would suggest two sprays are likely to be required. Even in a dry season, we can still get Sclerotinia lower down in the crop with microclimates under the canopy.

Aviator® (bixafen + prothioconazole) with two modes of action will help control both Sclerotinia and light leaf spot. If you decide on one spray, then go with 1.0 L/ha of Aviator, while if you split it 0.75 L/ha-0.8 L/ha with a second spray three weeks later if the crop is still flowering and at risk.


Ascra contains bixafen + prothioconazole + fluopyram. Vimoy containts isoflucypram. Proline contains prothioconazole. Revystar contains mefentrifluconazole + fluxapyroxad. Univoq contains fenpicoxamid + prothioconazole. Siltra contains bixafen + prothioconazole. Aviator contains bixafen + prothioconazole. Ascra, Vimoy, Proline, Siltra and Aviator are registred Trademarks of Bayer. All other brand names used are Trademarks of other manufacturers in which proprietary rights may exist. 

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