7 ways to keep crops on track this April in the West

Crop Progress

Crops changing quickly at this time of year. As this is written toward the end of March crops have started taking up applied nitrogen, and we’re reaching GS30 in some crops.

Some oilseed rape crops have gone backwards with larval damage, but generally they are looking better than this time 12 months ago.

Gareth’s agronomy tips for April

1. Final chance for weed control in wheat

A lot of weed control sprays were applied towards the end of March but any left need applying as soon as possible in April. That’s the first job. Don’t wait for T0s – not least because if you’re going to apply tebuconazole it doesn’t mix with mesosulfuron-containing products that are likely to be the backbone of your weed control.

2. Treat T0 as a yellow rust spray in wheat

T0 is now primarily a yellow rust spray and a chance to do some early growth regulation if you have any forward crops.

There was yellow rust in susceptible varieties, such as Kinetic, in early March which has been dried up by the frosts.

But I’m still not convinced you can be guaranteed that any variety with the continuing development of new strains won’t get it, so I think it will be worth treating everything with something cheap and cheerful, such as tebuconazole, at T0.

Make sure it doesn’t go on any more than four weeks in advance of your T1. The T1 timing is sacrosanct so try to work backwards from when you think that will be to help time T0s.

The big conundrum is what to do with early drilled wheat crops with Septoria. There is a justification for doing something at T0 but without chlorothalonil there will be less growers willing to do so with folpet on grounds of expense and efficacy.

3. Concentrate on timing at T1

Timing is the key driver for wheat T1s, but it is the most difficult to get right. Dissect plants and target final leaf three when it is fully emerged. That can happen at GS31 or GS32, so don’t get pumped up about nodal growth stages – it’s about leaf emergence.

If you’re too late you’ll be spraying leaf two and have exposed leaf three for too long, or too early and you’ll be spraying leaf four. So take your time, dissect some plants and get spray timings right.

Fungicide choice should be focused on Septoria and yellow rust, but also be mindful of mildew and eyespot, and very occasionally brown rust. To cover those you need something with broad spectrum activity, which is where Ascra (bixafen + fluopyram + prothioconazole) or Aviator (bixafen + prothioconazole) fit.

Ascra is the stronger product, but if you’re worried about eyespot, then Aviator with its higher loading of prothioconazole could be the better option. The same applies in lower disease pressure situations where 0.8 L/ha of Aviator is a cost-effective option.

Folpet can be added to either and can be a benefit, but it is less consistent than chlorothalonil and is likely a decision on a case-by-case basis.

4. Sign up for rapid disease detection tests

At both main timings just because you can’t see disease doesn’t mean it is not already in the crop. To help growers understand the risk of latent disease we’re offering the chance to sign up for our rapid disease detection service this season, which helps identify disease before symptoms are present to inform fungicide decisions.

5. Target GS30-31 for winter barley T1s

Unlike in wheat where it’s leaf emergence that’s critical, in winter barley growth stages can be used for timing fungicide sprays. Don’t wait for GS32 – by then the battle could be lost. Instead target GS30-31 with 0.6 L/ha of Silta Xpro (bixafen + prothioconazole), which will cover all the main diseases in barley at that timing.

Winter barley T1s are likely to be earlier in April, which means the T2s could be due by the end of the month. Don’t extend intervals beyond four weeks between the two sprays as barley diseases, such as net blotch, cycle quickly and once it appears you won’t be able to keep on top of it very easily.

At the later timing, Ramularia is also a consideration. Anything you can do to keep the crop from being stressed is important, and it might be worth including folpet to add to your Ramularia control.

6. Three reasons to consider Aviator as a flowering spray

With current prices of oilseed rape approaching £400/t those with decent crops of oilseed rape should find plenty of reasons to continue to protect and maximise their potential.

Our Spotcheck results have been finding plenty of light leaf spot this season, so topping up light leaf spot control at flowering to keep it off the pods is one reason to consider Aviator as a flowering spray, as well as for controlling Sclerotinia.

We’ve also seen consistent yield benefits in our Judge for Yourself trials, even in years where we haven’t had much Sclerotinia.

Timing is by mid-flowering with Aviator at 0.75-1.0 L/ha, which will give you three-weeks protection. If flowering is prolonged you may need a follow up application.

7. Pre-emergence weed control is best for potatoes

There are limited post-emergence weed control options in potatoes, which puts the emphasis on pre-emergence control. Understand whether your variety tolerates metribuzin to know whether that is an option.

If it is Artist (flufenacet + metribuzin) could be tank mixed in with Emerger (aclonifen), which will provide good broad spectrum weed control. Emerger is strong on weeds like fat hen, Polygonums and brassicas, but generally bolsters the whole spectrum.

In non-metribuzin tolerant varieties, mixes of Emerger with metobromuron or prosulfocarb and pendimethalin that will help target whatever weed spectrum you have.

All needs to be applied pre-emergence of the crop, and at least seven days before crop emergence. Watch out for cracked ridges, as you don’t want the crop to be poking through.