How to maintain yields in crops in April

Crop Progress

With the rain and the temperature warming up crops have come to life during March. There are odd bits of yellow rust in some wheat crops, and quite a bit of Septoria on lower leaves, especially in earlier drilled crops. In oilseed rape there has been a lot of Phoma and light leaf spot appearing lately.

Tom’s agronomy tips for April

1. Where to position Ascra in winter barley

The most responsive disease control timing in winter barley is T1 – GS30/31. Yield in winter barley is set through maximising ear numbers so tiller retention is crucial, and disease coming in during this period can cause the plant to abort tillers.

Key diseases are likely to be net blotch, Rhynchosporium and mildew – all diseases which Ascra(bixafen + prothioconazole + fluopyram) will be effective against, so unless you’re really worried about Ramularia coming into the crop later, I would use your one shot of Ascra at T1 using a dose of 0.9 L/ha.

If Ramularia is a key concern then you could delay its use until T2, and use Siltra (bixafen + prothioconazole).

In spring barley, opposite priorities may mean using Ascra as the second spray as Ramularia tends to be the more damaging disease.

2. Target yellow rust at T0 in wheat

In early April some wheat crops may require a T0 spray ahead of the first main timing later in the month. This timing is now really just to target yellow rust or mildew – but there’s quite a lot of varieties that are weak against yellow rust. Tebuconazole or a strobilurin can be used to take out yellow rust, while a mildewicide can be added if mildew is present.

3. Use CropCheck to help understand disease pressure in wheat

As we approach T1 in late April consider using our free CropCheck service to understand better what disease might be in wheat crops. This service, in conjunction with NIAB, uses qPCR analysis of leaves to detect latent (non-visual) infections of Septoria and yellow rust.

It’s not a prediction tool, but it is another helpful bit of information to help you make an informed decision about what to use at T1.

If you would like to use the service, please get in touch with me for a sample pack and instructions.

Timing at T1 is crucial – so get out the scalpel or penknife and dissect plants. You’re looking for final leaf three to be fully emerged on the main tillers.

Our fungicide offer at T1 is Ascra – with the dual SDHIs plus prothioconazole in the can it has a really nice place at this timing, offering broad spectrum disease control at a good price.

4. One or two flowering sprays in oilseed rape

Generally, oilseed rape crops in Yorkshire look fairly decent and much better than further south. Light leaf spot is being found by our SpotCheck service, so if that hasn’t been taken care of before flowering it might need to be considered along with protection against Sclerotinia.

Aviator (bixafen + prothioconazole) is a good option for a first or only flowering spray, just before mid-flowering or first petal fall, as it will protect against both diseases, and contains two modes of action. You also get the benefits of Aviator’s Leafshield formulation, which helps the product spread better giving better coverage on the leaf and dries faster.

Where crops are a bit uneven because of pest attack or frost damage, flowering might be protracted given the different growth stages. In these cases a second spray of prothioconazole three weeks after the initial application might be required.

5. Tackle weeds early in sugar beet

When soils warm up, beet drills will no doubt be in fields quickly, and with a decent beet price of £40/t, area might be increased this year.

While the derogation for neonicotinoid seed treatments has been granted, the high virus yellows forecast will mean growers should be looking to get to the 12 true leaf stage as quickly as possible when virus yellows becomes less of a concern. It also helps maximise yields, of course.

Weed control is a delicate balance between minimising competition for the young beet plants, and not knocking crops too hard with the herbicides.

Betanal Tandem (phenmedipham + ethofumesate) can help provide that balance – it can be applied from the fully expanded cotyledon and provides good activity on a range of broadleaf weeds, including cleavers, black bindweed and mayweed. Activity can be extended by mixing with a residual partner such as metamitron.

Typically you would use it in conjunction with a methylated rapeseed or vegetable oil, such as Mero. Adjust the dose depending on the forecast maximum temperature on the day of spraying, and don’t use if that is going to be above 21C.

6. Target weeds in potatoes with Emerger

Emerger (aclonifen) is a good choice to be the base of pre-emergence weed control programmes in potatoes. It has a good range of activity on weed species such as redshank, black bindweed and chickweed.

Some growers have been finding groundsel to be a particular problem – Emerger has some effect, although it’s not mind-blowing, but there are a range of mix partners, such as Artist (metribuzin + flufenacet), pendimethalin, metobromuron and prosulfocarb that can extend its range of activity.

Like any residual it will work better when there is moisture, but we also see good results in drier conditions.

Emerger does need attention when using – make sure you start with a clean sprayer, and avoid using nozzles or in-line filters with a mesh that’s too fine to avoid blockages. Half fill the spray tank with clean water and begin agitation before adding Emerger to the tank.

Maintain constant agitation during filling, transportation and spraying, and then clean out well after use.