Seven tips for agronomy decisions in March

Crop Progress

It’s not getting any easier in the East Midlands after another 90mm of rain with another 10 days still to go in February.

Crops are a real mixed bag – there are some cereals that look really good, where the residual herbicides were applied and are reasonably free from weeds. Then others haven’t survived or are looking quite backward. Hopefully well-timed nitrogen will help promote tiller growth.

With the issues getting crops established, Sustainable Farming Incentive options appear to have been popular.

Ellie’s agronomy tips for March

1. Keep focused on crop condition and growth stages

It’s not going to be an easy year for agronomy with crops so variable in growth stages and conditions. Crops have had a stressful winter, and, in my opinion, there is a high chance of damage if we don’t get our timings right.

Be cautious and stay focused on making sure leaf wax has re-established, for example after liquid nitrogen applications and before applying any mesosulfuron-based products.

When it comes to fungicide timings, assess crops on a field-by-field basis as crop growth stages are going to be very different and as well all know, correct timing especially for T1 and T2 is crucial.

2. Belt and braces weed control?

Where autumn-drilled wheat crops haven’t received any grassweed control as yet, you’re probably going to have go in with belt and braces treatments, such as Atlantis Star (mesosulfuron + iodosulfuron + thiencarbazone) or Pacifica Plus (mesosulfuron + iodosulfuron + amidosulfuron).

Both can deliver up to 15g/ha of mesosulfuron, although you can only use the 0.5kg/ha rate of Pacifica Plus delivering that rate of mesosulfuron if brome is a target. The 7.5g/ha of thiencarbazone in Atlantis Star will help potentially give a little more control of grassweeds on top, but there are more restrictions on what you can tank mix, sequence and following crops with the product so look carefully at labels before choosing which one to use.

In some places you might want to add in a residual herbicide, but it will depend on crop and conditions. Residuals worked well in the autumn because there was plenty of moisture, and at current moisture levels you could still get useful efficacy from them, if you’re expecting further weed flushes. But crops are stressed and backward so care will also be needed to avoid crop damage.

3. Maintain tillers in winter barley

With many winter barley crops not particularly well-tillered it will be important to maintain as many viable tillers as possible to maximise yield. Keeping crops free from disease around GS30/31 is key to avoiding plants from aborting tillers.

There is a fair bit of brown rust in hybrid barley crops and mildew more generally, which might warrant a T0 if it starts threatening tiler viability, while a broad-spectrum fungicide at T1, such as Ascra (bixafen + fluopyram + prothioconazole) is a sensible choice.

You can only use it once in a programme in winter barley, so I would opt to use it at T1 because that all round strength, especially against net blotch. But if you’re concerned about Ramularia you could choose to save it for T2 against that disease and use Siltra at T1, which will also give good broad spectrum control.

Both products are formulated with Leafshield, which means it is quickly rainfast. That might be important in a season like this with lots of jobs coming at the same time.

4. Assess disease risk based on drilling date and varietal resistance

Variety and drilling date will influence disease risk in wheat crops. Remember the AHDB varietal resistance ratings are based off a 7 October drilling date, so if you drilled a couple of weeks earlier Septoria ratings, for example, will crop by 0.6, which could move a variety from a six to a five depending on when you drilled.

Yellow rust is perhaps the opposite with higher risk in late drilled crops. It was already in some crops, including Extase, in February.

Trash is another factor to consider. If there is a lot of trash for disease to overwinter in that might need to be factored in.

For T0s I’d be looking mostly at yellow rust as the trigger. It can be a long time to T1, so if disease is present a little bit of tebuconazole to clean it up. It doesn’t take much for it to become a problem through the season.

5. Look out for light leaf spot in oilseed rape

Not many growers will have applied an autumn fungicide to oilseed rape – not that much has survived unfortunately. What has survived looks decent though, although larval pressure in stems is severe.

Assuming remaining crops survive through that, then they will be worth protecting, and light leaf spot is a key threat to watch out for in March. The old technique of putting leaves in a plastic bag somewhere warm for a few days will help show any symptoms. Where appropriate a Proline (prothioconazole) spray could be justified.

6. Check for Conviso sugar beet survivors

For growers who have grown Conviso herbicide tolerant sugar beet varieties in the past, check land for groundkeepers. Keep in mind ALS herbicides won’t control them, so your best bets are hormone weedkillers like MCPA or 2,4-D.

It’s also key to control any groundkeepers and spoil heaps to prevent a green bridge for virus yellows carryover.

7. Test potato ground for PCN

If you haven’t already tested potato land for potato cyst nematode populations, now’s the last chance before planting begins next month.

Where counts are high nemathorin is the product of choice, but if counts are lower (3-5 eggs/g soil) then there is the option of using Velum Prime (fluopyram). It can also be used in conjunction with nemathorin where appropriate.