Seven suggestions for crop agronomy in East Anglia this March

Crop Progress

January was very dry, February less so, but generally crops are looking well. A lot of winter wheat was drilled relatively early in late September or early October, and because it has been so mild, nothing has really stopped growing.

That means there are quite a lot of forward, thick crops around, and quite a bit of disease pressure, with Septoria easily found regardless of variety as we approach the end of February. Mildew is also not difficult to find, although yellow rust is less evident.

Winter barley is similar with nice forward and thick crops, with net blotch, Rhynchosporium and mildew at fairly low levels.

Most oilseed rape has moved away from adult cabbage stem flea beetle damage. We are finding larvae in petioles, but they don’t have migrated to the main stem in any great numbers so far. Pigeons appear to be as much of a problem as anything for rape crops currently. Monitor crops to see how they respond to any significant attacks.

James’ agronomy tips for March

1. Assess wheat fields for weed control needs

Generally, weed control from pre-emergence and / or early post-emergence residual herbicides in wheat has been good. I recently saw a spray miss in a field where there were around 200-250 black-grass plants / sqm in the missed 50cm strip, with hardly any black-grass plants in the Liberator (flufenacet + diflufenican) + Proclus (aclonifen) treated part.

But where grass weeds have escaped control, the mild weather will have helped them grow, the same as the crops so walking fields to assess what has come through, identifying the enemy and likely pressure, will all help with decisions for this spring.

Ideally, where another application is required, then I’d suggest trying to get on at the first opportunity, as soon as fields are fit to travel and temperatures are starting to warm up. It’s often better to take the chance to spray and targeting weeds when they are smaller, than letting them get bigger and waiting for perfect conditions.

The proviso is avoid spraying off the back of frosts – you need the weeds to be actively growing for efficacy.

Pacifica Plus (mesosulfuron + iodosulfuron + amidosulfuron) will give broad spectrum activity against grass weeds and broadleaf weeds. If brome is a target from 1 March you can use the higher 0.5 kg/ha rate, otherwise it is 0.4 kg/ha.

Where you are drilling spring barley, a reminder that Liberator has a label recommendation for the crop at 0.3 L/ha for pre-emergence only.

2. Target tiller retention in winter barley 

Looking after tillers in winter barley is crucial as that’s how you maximise yields – it’s about the number of ears rather than filling the grains. Keeping the crop healthy helps minimise the risk of the crop aborting tillers and therefore reducing yield.

That could start with a mid-March, end tillering spray at T0 if you’re worried about net blotch or mildew, but assess the need for it. If the crop is being held back by disease and stopped from growing, then a Proline (prothioconazole) could be helpful to clean up infections.

Otherwise, you’re waiting for the more critical timing of T1 (GS 30/31). New this year, Ascra (bixafen + fluopyram + prothioconazole) has a recommendation for use in barley, including on winter crops. But you can only use it once in the programme so think about what disease risk you’re likely to face, as it could fit at either T1 or T2.

 If you’re concerned, for example, about net blotch, our data would suggest that Ascra at 0.9 L/ha would make a very good base at T1. Alternatively there is positive data for its use at T2 for the suppression of Ramularia, so you could save its use to T2 for that disease and use Siltra (bixafen + prothioconazole) at T1 at 0.6 L/ha.

3. Reduce yellow rust pressure at T0

 Reducing the risk of yellow rust will be the key focus of T0 in wheat, which will likely be around the end of the month, or shortly into April. Check disease pressure and variety to target and decide whether this application is necessary. Yellow rust has a short latent period of around 14 days, so where conditions arise that are high risk, it’s important to be on top of the it rather than chasing through the programme.

If you do need to apply a fungicide, tebuconazole at 125 g a.i./ha would be the product of choice.

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 qPCR 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. Monitor for light leaf spot in oilseed rape

Continue monitoring for light leaf spot in oilseed rape. Our SpotCheck service, part of CropCheck, will be available until the end of March to check leaf samples for signs of the disease.

If you haven’t applied anything in February, then Proline at stem extension could be needed.

6. Focus on getting sugar beet to 12 true leaves as quickly as possible

As this is written the decision around neonicotinoid seed treatments in sugar beet to help control the aphids transmitting virus yellows has not been taken, but given the weather it looks likely the conditions attached to the emergency authorisation will be met this year.

Even so, with those treated done so at a lower rate than previously, and a good proportion of crops remaining untreated it will still be important to get to that magic 12 true leaves stage when adult plant resistance kicks in as soon as possible.  

Weed control is an important part of minimising crop competition and maximising growth. Depending on when crops are planted and how quickly they emerge, first post-emergence applications could be in late March or into April.

We had good feedback about Betanal Tandem (phenmedipham + ethofumesate) last year in the first season without desmedipham. It’s a good broad-spectrum herbicide, which can provide the backbone of weed control programmes from the expanded cotyledon stage.

7. Consider Velum Prime for potato cyst nematode control

Feedback from last season was also positive for Velum Prime (fluopyram) – our liquid nematicide. There’s flexibility over application method – either as an in-furrow application or an overall spray, which then needs to be incorporated. From 22 trials over several seasons, it has not been possible to split the two methods.

In low pressure PCN situations, Velum can be used alone, while in medium to high pressure fields it’s possible to use in conjunction with either half or full rate of a granular nematicide (Nemathorin 10G) for improvement in average yield protection and PCN population management.