Insect pest pressure found rising in winter wheat crops

The next few weeks are critical for yield and AICC agronomist Antony Wade points to several threats that could spoil otherwise reasonable looking crops. For example, the mild winter may see crown rust in oats.

Sean Sparling highlights that yellow rust and septoria pressure remains high and aphid numbers are rapidy rising in wheat crops.

For Paul Sweeney, it’s barley yellow dwarf virus that is spoiling wheat crops, as it becomes evident that aphids were flying in December.

Finally, Richard Harding looks ahead to the T3 fungicide timing and believes aphid control may also need to be considered in the mix.

Read their reports below.

East: Sean Sparling

AICC (Lincolnshire)


It’s the beginning of June and, for the first time in a few years, we are still applying flag leaf sprays to the later drillings.

Fortunately most of my winter wheat has had its flag leaf spray protecting it for 10 -14 days and that could prove very important in the weeks to come. Currently the septoria and yellow rust pressure is as high as I’ve seen it for a number of years.

Aphid numbers are rapidly increasing in wheats and so we may have to deal with this pest for the first time in a number of years.

It all now depends upon the weather – because if those forecasters are right and it does come hot and dry for the next three months, brown rust will be the issue. Unfortunately, the same people predicted that it was going to be a long cold summer of Atlantic storms, so hedging one’s bets will once again be the best approach.

Oilseed rape is now going out of flower rapidly, I think most of us would say that light leaf spot has been a challenge this season, sclerotinia has been less so thanks to the cool weather.

However, there have been some issues with some of the more backward oilseed rape crops where late frosts have caused some main racemes to abort all buds and, therefore, setting no pods. This seems confined to the areas which were slow getting away in the autumn and equally slow this spring.

It could be attributable to all aspects of stress and we have seen this before. Yields are always better than they appear – we will wait and see.

Linseed is being slaughtered by flea beetle in some areas of Lincolnshire, with several fields being written off on one farm alone, despite multiple applications of insecticide. Are we getting to the stage where oilseed rape and linseed are going to be impossible to grow without neonicotinoid seed dressings?

South: Richard Harding

Procam (Sussex)


Winter barley crops on the Downs are now all fully out in ear and looking impressive. Ideal growing conditions during May have really helped late-sown spring crops get well established and more borderline winter crops are now showing potential.

Forage maize has been going into ideal seed-beds and good levels of moisture are also allowing well-timed pre-emergence herbicide applications of pendimethalin.

Wheat ears are emerging on many crops now and have emerged on the more forward crops for a number of weeks. Many T2 fungicides are only just being completed in some areas, but T3 options now being planned.

These will be largely based around prothioconazole, tebuconazole and spiroxamine for late mildew control, which seems more noticeable this season.

The optimum timing for best effect on fusarium and mycotoxins is pre-flowering which is likely to mean a short interval between the T2 and T3  applications for some crops.

Aphid numbers are still high despite recent cooler conditions and will continue to be monitored, and control may need to be factored in with the T3 fungicides. Numbers are also building in pulses, particularly peas.

Both chocolate spot and rust are building in winter beans, with many having had or due to have a T2 fungicide application of cyproconazole + chlorthalonil. Bruchid beetle monitoring is now taking place as spring beans move towards flowering and first pod set.

Overall oilseed rape crops are looking like they have good yield potential. The latest sclerotinia report for this season shows the risk levels are dropping with many crops now at the tail end of flowering and are back to an overall green appearance again.

North: Paul Sweeney

AICC (Cheshire/Lancashire)


With a good spell of settled weather, crops have now made up for lost ground. Fungicides applications at the T2 timing were all finished in good time and no “septoria time bomb” appeared – surprise, surprise.

All we need now is more rain because it’s been quite dry in Cheshire and very dry in Lancashire, especially near the coast. Winter crops will be fine for a while, but spring sowings are starting to struggle already.

Oats are coming to head slowly and should have something cheap to keep crown rust away, probably a low dose of strobilurin to help improve specific  weights.

What is spoiling many wheat crops is the amount of barley yellow dwarf virus, especially in those surrounded by trees. Infection is not severe in terms of stunting, it’s more just extensive yellowing, so they will hopefully tolerate it without a great impact on yield.

Given that it has affected both crops with insecticide seed treatment and those sprayed with insecticide up to mid-November, it must be down to aphids arriving just prior to Christmas – when it was so wet that treatment was impossible anyway.

There is a bit of mildew in the wheat, but nothing to worry about – and the rust problems seem to have been well controlled with fungicides. Septoria control has been excellent and will remain so as disease pressure has abated.

They can wait till heads are fully emerged and then be treated with T3s as soon as flowering commences with something effective for fusarium species, but there is no need to throw excessive cash at them now.

Spring cereals have developed rapidly, but need more rain soon if they are to stand a chance of coming to something reasonable. Make sure that weed control is effective and disease, especially mildew, is controlled.

West: Antony Wade

Hillhampton Technical Services (Herefordshire/Shropshire)


I always think winter crops in late May and into early June can look their best, although they can both flatter and deceive when it comes to the end of the season, as the coming weeks are critical in terms of final yield.

Flattery comes in the form of barley that has now romped into ear, finally put on some normal height and wheat with visible septoria symptoms confined to lower leaves and yellow rust kept in check.

Then there are oats with low mildew levels and are short thus masquerading as having a low lodging risk and oilseed rape with good open canopies and not too tall.

Potential deception may reveal itself in brome, ryegrass and wild oats eventually overtaking barley and spoiling the uninterrupted sea of awns and in wheat, uncontrolled septoria infection after a delayed T1 reducing green leaf area early and limiting efficient radiation conversion.

Crown rust may erupt in oats after a mild winter reducing grain filling and specific weight and oilseed rape stems with abundant light leaf spot.

Spring crops are still early in their short season that has to be even faster paced than normal due to later than ideal sowing dates, but also look to have made a good start.

Barley is tillering well and getting its first fungicide, growth regulator and herbicide where pre-emergences were not applied. Beans have got away without significant pea and bean weevil damage and are now out of danger with pre-emergence herbicides having done a good job generally.

Hopefully, my predicted deceit will be outweighed by the flattery helped by some good yield forming radiation over the coming weeks. But I am fairly sure that the flattery won’t get us anywhere near the performance levels which we saw from most crops last season.

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