Agronomic help for East Anglian growers in April

Crop Progress

As I am writing, catching up on farm is a very mixed picture – there are some forward crops on lighter land that have had nitrogen applications and looking reasonable, while others are still only just emerging.

There’s also a chunk of area still to be drilled, which will now be spring crops, which in some places it is now dry enough to get on, and other areas which are definitely out of bounds.

Rachel’s agronomy tips for April

1. Drilling date will change disease risks

With such a wide window of wheat drilling dates, that will change disease risks in crops. The early drilled, forward crops will likely have more Septoria bubbling around underneath than the later drilled ones, but in later drilled crops the yellow rust and mildew risks will be increasing and Septoria decreasing.

Coupling that with variety choice that could mean the crop is exposed to a risk you weren’t necessarily expecting.

Careful crop walking will help assess those risks and help you decide on appropriate fungicide programmes.

In early April yellow rust is probably the greater threat – there were already reports of yellow rust in crops in March in varieties, such as Extase and Zyatt. Where that threatens a T0 spray is likely to be required but it doesn’t need to cost much as a tebuconazole is likely first choice.

If there are high levels of Septoria in susceptible varieties then that potentially might need something to dampen it down ahead of T1, although without chlorothalonil the options are less appealing.

Mildew is the other disease to watch out for around T0 – a specific mildewicide might be required if levels are such that you don’t think waiting until T1 is an option, or that the weather will dampen it down.

2. How much should you spend on wheat disease programmes?

How much to spend is likely to be a debate that rages across social media and other forums this spring. Yes, yield potential is likely to be compromised in some crops, but it can become a self-fulfilling prophecy if you cut inputs so far that it becomes a low input, low output scenario. Just because yield potential has been compromised doesn’t mean disease pressure will automatically be lower either.

If you have given or can give the crop some TLC in the coming weeks to help it recover through encouraging better rooting and maintaining or increasing tiller numbers, you might be able to achieve a higher yield than if you hold back on spending.

But it is a tricky one to judge and will be very dependent on each farmer’s attitude to risk.

3. How to correctly time T1s with such variability in crops?

Correctly assessing crops for the T1 timing is going to be challenging in some situations, especially where the field is now patchy and plants are all at different growth stages.

In that situation the best plan is likely to be to dissect plants from a representative area of the field – perhaps the most forward part as that is likely to produce the best yield – to check for final leaf three emergence. Don’t go just from node emergence as that might not coincide with final leaf three, especially in either very forward or backward crops – it’s better to check for dissecting than guess as timing is crucial for programme efficacy.

In most crops a fungicide with broad spectrum activity against diseases such as Septoria, yellow rust and eyespot will make sense at T1. From our stable Ascra® (bixafen + prothioconazole + fluopyram) is a proven one-can solution and priced competitively.

Where are you wanting some extra efficacy and happy to spend a little more money, we also have the newly available Iblon® range. Vimoy® (isoflucypram) is co-packed with prothioconazole products, including Proline® (prothioconazole) and offers a step up in efficacy of key diseases. In most cases I would suggest using 1.0 L/ha of Vimoy plus 0.5 L/ha of Proline, but in higher pressure that can be increased to 1.2 L/ha + 0.6 Lha.

4. Net blotch concern in winter barley

Maintaining tillers will be vital in maximising yield potential in winter barley because of the strong link between viable ear numbers, numbers of grains / sqm and final yield.

One of the causes of tiller abortion as the crop starts to stem extend can be disease, making the T1 spray more important than the flag leaf spray in the crop. Diseases to watch out for include net blotch, Rhynchosporium, brown rust and mildew, which is why broad-spectrum fungicides like Ascra® or Siltra® (bixafen + prothioconazole) show good results from this timing.

Net blotch is becoming more of a concern, and where it might tip the balance towards using Ascra, as data shows better performance against that disease.

Later in April or early May depending on growth, a second fungicide application around GS37-43 will likely be required. If you’re worried about Ramularia and didn’t use your one application of Ascra at T1, that might be where you want to position it. But for more growers the higher response will come from the T1 spray.

5. Will flowering be prolonged in oilseed rape

Stem extension had started in oilseed rape crops by mid-March and by the end of march most fields had at least a good portion of yellow. One of the issues being that under some of those flowers is lots of uneven crops which have not hit stem extension yet at all.

If crops are more even then one application might cover most of the petal fall, but with lots of variability in fields, this might cause flowering to be prolonged, and push towards a two-spray programme for Sclerotinia and light leaf spot control.

Either way Aviator® (bixafen + prothioconazole) is a strong option to consider with its dual mode of action helping protect prothioconazole from resistance which is used a lot in this crop.

The SDHI bixafen will also help provide some physiological benefits to the crop, which is one reason why we see yield responses from the use of Aviator® in the absence of disease.

6. Weed control in root crops

Hopefully by the time you read this the weather has improved, as well as the last batches of neonicotinoid treated sugar beet seed arriving on farm, to allow drilling of beet and potato planting to be well underway.

In both crops early season weed control is important for allowing the crop to establish unimpeded and not to compromise yields.

In sugar beet Betanal Tandem® (phenmedipham + ethofumesate) provides a solid base for programmes. It can be used up to three times, usually in mix with a residual partner such as metamitron from early post-emergence.

An alternative system if you’re growing a tolerant variety is Conviso®. Remember stewardship with this system is important to maintain its benefits and to make sure you don’t accidentally spray the wrong field as the Conviso One (foramsulfuron + thiencarbazone-methyl) will kill conventional beet.

Conviso One timing is ideally around the 2-4 TL stage of an indicator weed species, such as fat hen. You only get one shot with Conviso One so timing is important to maximise its efficacy.

In potatoes, Emerger® (aclonifen) can provide the base weed control after a pre-planting Roundup® (glyphosate) has been used to control any weeds growing before potato planting begins.

Emerger® is a true pre-emergence herbicide so should be applied at least seven days before crops emerge, again, usually in mix with another herbicide to broaden spectrum and efficacy. Both Artist® (flufenacet + metribuzin) and Sencorex® Flow (metribuzin) are possible options if the variety is tolerant to metribuzin.

Acknowledgements

Ascra contains bixafen + prothioconazole + fluopyram. Vimoy containts isoflucypram. Proline contains prothioconazole. Siltra contains bixafen + prothioconazole. Aviator contains bixafen + prothioconazole. Betanal Tandem contains phenmedipham + ethofumesate. Conviso One contains foramsulfuron + thiencarbazone-methyl. Emerger contains aclonifen. Roundup contains glyphosate. Artist contains flufenacet + metribuzin. Sencorex Flow contains metribuzin. Ascra, Vimoy, Proline, Siltra, Aviator, Betanal Tandem, Conviso One, Emerger, Roundup, Artist, Sencorex Flow are registered trademarks of Bayer. All other brand names used are Trademarks of other manufacturers in which proprietary rights may exist.