Final agronomy jobs for western growers in June and July

Crop Progress

There was plenty of Septoria in wheat crops especially lower down the canopy on leaves four and five, as flag leaves started to emerge following two wet months. Is it the worst year we’ve ever seen, as some are saying? I’m not so sure. Drilling date and variety are the two biggest factors in how bad it is, but even with the best chemistry available now, you will always have Septoria in crops.

On the plus side, it’s probably been the lowest yellow rust year we’ve had for a long time, and I’m yet to see any brown rust. But we have seen a lot more eyespot this season because it has been wetter and there are more varieties being grown with susceptibility.

Other crops look promising, with the exception of some later drilled spring barley which has really struggled in the recent wet weather.

Gareth’s agronomy tips for June and July

1)      Decide on T3 priorities

The first decision around ear sprays is deciding what you want it to achieve. In my mind it is probably Fusariumcontrol, brown rust and Septoria top up in that order.

Timing is key, especially for Fusarium – we have lots of information on best timing, which is early to mid-flowering. Remember wheat ears don’t start flowering from the top or bottom of the ear, but from the middle. Once you see those first anthers it’s time to spray because if you’re too late or too early it reduces the effect the fungicide has on the disease.

In a usual year, I always think the first week of June is too early, and the second week of June is too late – it’s sort of at the end of that first week, but it shows how tight the window can be.

That means it might only be a couple of weeks after flag leaf sprays have been applied, but remember those two sprays are doing completely different jobs, if you’re targeting Fusarium control. In some years, some growers try to combine them into one spray, which means you’ve done a good job in missing both timings.

Prothioconazole is good against Fusarium, but its Achilles heel is wheat brown rust. Products like Prosaro (prothioconazole + tebuconazole), Firefly (fluoxastrobin + prothioconazole) and Aviator (bixafen + prothioconazole) all include partners that will help improve brown rust efficacy. Brown rust has a really short latent period and is driven by temperature, so if it goes warmer and you haven’t done a good job, it can go from a clean to dirty crop in a week.

Remember applications of SDHIs (and strobilurins) are restricted to a maximum of two per season, but if you’ve used a fenpicoxamid type product as T1 or T2, that could open up the potential to use an SDHI-containing product at T3, like Aviator. It’s not as cheap as some other options, but I think it fits, especially on good wheat growing land where you need extra Septoria protection for longer. Wheat yield is driven by how late you can keep the crop green – research has shown the number of extra days you can keep crops green is directly correlated to yields – so it’s not just milling wheat this applies to but also feed wheat.

2)      Map weed patches

June is the ideal month to map fields to determine the success of herbicide programmes. Our digital platform Climate FieldView will help make this easier by enabling you to add notes to fields. It’s the old adage of what you can’t measure and monitor, you can’t manage, so June is perfect to see what’s happened and then you can make any required changes to your herbicide strategy, starting with rotation and cultural controls.

We have a one-year free trial for new users If you’re interested in trying FieldView.

3)      Desiccation timing in oilseed rape needs care

Don’t be too keen when it comes to spraying off oilseed rape with Roundup (glyphosate). YEN OSR has shown that, like wheat, yield and oil content are added late in the season, so going too early can be costly.

Growth stages vary in fields as well as between fields, and while it’s not the easiest or most pleasant of tasks to get into the middle on an oilseed rape crop at this time of the season, it’s worth making the effort to get into the field rather than just looking at headland in the gateway.

You’re looking for moisture content below 30%. This guide talks you through how to do that visually in three easy steps starting with selecting 20 pods at random and what colour change of the seeds look for.

While it is probably better to be a bit late than too early, glyphosate does need some green leaf to get taken into the crop. Watch out for the top of the crop being burnt off in hot weather – as ever, timing can be a bit of a compromise.

4)      Assess what’s important for you in oilseed rape varieties

There are lots of field days around the country in June and early July. The local Bayer one in the west is at Callow, Herefordshire as usual, and has, alongside wheat variety plots and fungicide programme, oilseed rape variety trials.

There’s an extensive range of Dekalb hybrid varieties, which, between them, will suit various situations. Think about your intended likely drilling date and look for a variety to suit. Some varieties will be quicker to get away in the autumn, some are have stronger spring vigour.

All our varieties have pod shatter resistance, most have good disease scores, while there are varieties with Turnip Yellows Virus (TuYV) resistance, Clearfield tolerance, etc.

One advantage of hybrids over conventional open-pollinated varieties there is both more flexibility with drilling date and a closer correlation between seed rate and final plant populations. It’s better to avoid sowing oilseed rape too thick as the plants compete with each other. If you go lower it will branch more, which is better for canopy structure and ultimately yield.

5)      Look out for potato blight

Given the weather so far in May, it’s possible there’s going to be blight pressure very early this season. Keep an eye out for both early (Alternaria) and late blight (Phytophthora infestans) – you don’t want blight to establish in crops so don’t start programmes too late.

We have Infinito (propamocarb + fluopicolide) for late blight and Caligula (fluopyram + prothioconazole) for early blight. Infinito has good activity against tuber blight, as well as foliar late blight so fits well from canopy complete, but can also be used during the rapid growth phase of the crop. The beauty of it is it fits through the programme, so realistically when you need a strong product, you can fit it in, bearing in mind its maximum of four applications.

For varieties susceptible to early blight, Markies being the obvious one, Caligula is a good choice. In EuroBlight trials it has been shown to be the strongest product available against early blight, but remember it gives no control of late blight.

6)      Target small weeds, as late as possible in maize

Here’s another timing compromise. MaisTer (foramsulfuron + iodosulfuron) is the best product available in maize for broadleaf weeds and grassweed activity.

It’s an ALS inhibitor so needs good growing conditions for best results. It also doesn’t have much residual activity so while you want the weeds to be small for efficacy, you also want them to have all to have emerged. But if you leave it too late, coverage can be an issue with the maize crop, as well as weeds going beyond the ideal 2-4 TL.

In an ideal world, you would go as late as you can in good growing conditions targeting small weeds. But in the end it will be a compromise.

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