Seven agronomic insights to help manage crops in March in the Midlands

Crop Progress

Other than a few crops under water following the February storms, in general cereal crops were looking fantastic as we approach March.

In wheat, there’s some mildew around and Septoria on the older leaves. Our latent disease testing service, CropCheck, is finding Septoria in the latest emerged leaf. So far there haven’t been many reports of yellow rust, but that’s likely to change in susceptible varieties.

There have been reports of net blotch in winter barley, and watch out for mildew as well.

There are some very forward oilseed rape crops – in February we were finding a lot of cabbage stem flea beetle larvae albeit not having made the migration into the main stem. Time will tell what the impact of that will be.

Adam’s agronomy tips for March

1. Control later emerging grass weeds in wheat

We had fantastic conditions in the autumn for most growers to get on with their autumn residual weed control programme, whether that was a pre-emergence and / or early post-emergence application. Pre-emergence Liberator (flufenacet + diflufenican) + Proclus (aclonifen) has worked particularly well in both black-grass and ryegrass situations.

But inevitably there will be later germinating grass weeds in the spring, which will need controlling to reduce weed seed return for following seasons.

There are various options from the autumn and spring-applied OD formulations such as Atlantis OD (mesosulfuron + iodosulfuron), which allow a flexible approach, but as we move into March the option of Pacifica Plus (mesosulfuron + iodosulfuron + amidosulfuron) would be my go to product especially for tougher grass weeds.

From 1 March you can use Pacifica Plus at 0.5 kg/ha where you are targeting brome, but it also gives you cover for broadleaf weeds as well.

Where you only have brome species without many broadleaf weeds, Monolith (mesosulfuron + propoxycarbazone) is also a good option.

2. Consider whether a T0 is required in winter barley and winter wheat

Yield responses to fungicides are highly variable at the T0 late tillering timing in winter barley, so the decision to use has to be considered carefully. There is plenty of inoculum in crops with the mild winter.

In barley the main diseases to consider are mildew, Rhynchosporium and net blotch. If mildew is threatening then a specific mildewicide is an option, while there is also the multisite folpet, but I’d avoid using a primary azole at this timing.

In wheat the case for T0s is a little stronger – especially where yellow rust threatens. It is important to get on top of yellow rust so you’re not chasing it all season. Tebuconazole is a good choice, plus a strobilurin if you need quicker knockdown.

3. Plan T1 winter barley strategies

Unless there is some seriously cold weather in March to slow down growth it would seem likely that T1 applications in winter barley could be due at the end of the month, especially in the forward crops.

Yield is driven by tiller retention, which means that T1 (GS30/31) is the key timing for disease control to prevent tillers being aborted.

Ascra Xpro (fluopyram + bixafen + prothioconazole) is now registered for winter barley, including for malting crops. It can only be used once in the season, which means thinking about what you are trying to achieve and whether to use it at T1 or T2.

In trials we have the benefit of fluopyram in Ascra is increased activity against net blotch over what we see with Siltra (bixafen + prothioconazole), but there is also good trials data to support increased activity against Ramularia, so it could fit at either timing.

My advice would be to use Ascra at 0.9 L/ha at T1 for early disease control of those challenging to control diseases at that timing, especially net blotch, and following up with Siltra at T2, unless you are very concerned about Ramularia, in which case you could swap it around.

4. Consider using new CropCheck service to assess disease risks

Expanding on our Rapid Disease Detection service from last season, this season’s CropCheck service includes testing for latent infections of Septoria and yellow rust in winter wheat, Rhynchosporium and net blotch in winter barley, as well as light leaf spot and other diseases in oilseed rape.

The CropCheck service in wheat and barley uses PCR analysis of the leaf to assess whether a disease is present in the leaf before it is showing symptoms giving extra information to help you understand risk in your crops.

It’s important that it’s not used as the only part of your decision-making process though – it is only a snapshot in time and all the other factors you would normally use to help with decision-making, such as variety choice, weather, drilling date, etc., are equally, if not more important.

To register your interest in CropCheck click here.

5. Watch out for light leaf spot in oilseed rape

The jury is out on light leaf spot – some agronomists are finding it quite easily, others are saying the crops are clean, so it does seem to be a field-by-field basis. Our SpotCheck service is a good way of checking whether you do have it in your crops.

If you are finding it, then Proline (prothioconazole) at stem extension will help keep it from moving up the plant onto the flowers and the pods. In forward crops you might also consider growth regulation – in which case adding in some tebuconazole will help provide that effect.

6. Minimise weed competition in sugar beet

While the official virus yellows forecast has yet to be published as this is written, the likelihood seems, given the relatively mild weather in January and February that the conditions for the emergency authorisation of neonicotinoid seed treatments will be met this season.

That’s good news for minimising virus yellows damage, but there will still be a significant proportion of crops that won’t be treated, while those that are, will be treated with a lower dose than was previously the case.

It means that getting the crop to the 12 true leaf stage as quickly as possible will remain crucial for reducing the virus yellows threat, as well as maximising yield potential.

Minimising weed competition is an important aspect for both growth and yield potential so pay attention to the weed populations present and carefully use herbicides to avoid checking the crop.

Betanal Tandem (ethofumesate + phenmedipham) mixed with a residual such as metamitron will provide broad spectrum weed control. In trials it has given 10% better fat hen and black bindweed control compared with generic tank mixtures of the actives and 30% improved control of field pansy.

Follow label guidance when adding in oil to maximise efficacy without increasing potential for crop damage.

7. Consider benefits of a liquid nematicide in potatoes

With tight rotations in some parts of the Midlands for potato crops, potato cyst nematodes infestations remain a challenge. Using cultural controls as part of an integrated approach is becoming ever more important.

We’re now down to just one granular nematicide, with Velum Prime (fluopyram) as a liquid alternative. Velum Prime can be applied either as in-furrow application or an overall spray which then needs to be incorporated to a depth of between 10 and 30cm after destoning.

The addition of the overall spray, incorporation method opens its use to a lot more potato growers, and alongside easier application than with granules, a very low use rate of 0.625 L/ha means Velum is much easier to handle.

In low pressure situations you can consider using it alone, while in medium to high pressure PCN use it conjunction with a half or even full rate granular nematicide to provide yield protection and population management as part of an integrated PCN management plan.