Changeable weather with extremes in temperature is resulting in stop-start crop growth, which is making it more difficult for agronomists to predict spray timings.

The cooler conditions this week are also making it tricky to time bentazone applications in winter beans, as the herbicide needs warm weather for the best efficacy. Delaying too long risks missing the safe application window.

North: David Martindale

Arable Alliance (Yorkshire)

The month of March was mostly dry, which allowed good progress to be made with spring drilling. Seed-beds have been adequate and most crops have been sown into moisture, the exception being some heavier land that had begun to dry out.

See also: Norfolk farmer goes digital to get spray timing spot on

September-sown cereals appear to have thrived relative to their October-sown counterparts in the cool and dry conditions. These later-sown crops have struggled to get going and now could do with some rain and higher temperatures to promote growth.

T0 fungicide and growth regulator mixes are being applied to winter wheat crops. Yellow rust levels have increased in the past fortnight, although infection levels are variable, even in the same variety.

It is not uncommon to see yellow rust at alarming levels in one field, yet in the same variety a short distance away it proves difficult to find. Azole fungicides such as tebuconazole or epoxiconazole are being used to combat the rust.

Thankfully, the Septoria tritici pressure has eased for now in these current cool and dry conditions. The level of growth regulator input required is quite modest due to more wheat crops being sown later, with the consequent lower lodging risk.

Earlier-sown winter barley crops have improved significantly and are currently receiving their T1 fungicide mixes. Net blotch and brown rust have been the two main diseases, with the latter being very prevalent in some hybrid varieties such as Kingsbarn.

The dry weather has yet to cause a major flush of annual broad-leaved weeds. Only charlock, cleavers and volunteer oilseed rape emergence is of any significance, and they are being controlled with a herbicide to be mixed with the T1 fungicide.

Crops sown into wet conditions in October on heavier soils have a lot of catching up to do if they are to make respectable yields.

Rapid rye

Winter rye has moved into the explosive phase of rapid growth and development. It remains impressive to see just how fast this crop grows. Plant growth regulators are being applied, with robust rates used on more fertile fields.

Brown rust levels have remained low, although the first pustules have appeared after the three hot days at the end of March. Fungicides are being applied to keep brown rust under control, as well as mildew in some varieties.

The earliest crops of oilseed rape have begun flowering and most crops look particularly well. The hot spell saw a rapid increase in pollen beetle numbers, with crops vulnerable at the green to yellow bud stage.

The thresholds to spray and control pollen beetle allow for significant numbers to be present, which can seem disconcerting. I have not found any crops where pollen beetle numbers were exceeding the treatment threshold levels, so no insecticides have been required.

Light leaf spot levels have continued to increase and fungicides and/or plant growth regulators have been applied on the more advanced crops. It will not be long before attention will move to considering sclerotinia prevention.

Winter beans have a range of growth stages, depending on when they were sown, with the earliest crops approaching the flower buds enclosed stage.

Bentazone is being applied to control weeds such as charlock and volunteer oilseed rape, but the application timing is proving difficult as warm weather is required for the best herbicide efficacy. 

If we delay for too long while waiting for better conditions, there is a danger of missing the safe application window.

West: Neil Potts

Matford Arable (Devon)

Yo-yoing weather means crop growth is all at sixes and sevens. Daytime temperatures have been bouncing between the low 20Cs and just above freezing.

Crops are looking well, but predicting the timing of growth stages is proving a bit tricky, with crops going through stop-start periods of growth.

Most winter barley crops and many wheat crops have now received their T0 fungicides. The fluctuating temperatures mean many winter barley crops seem reluctant to stop tillering and move into their reproductive stage of growth, so they are not yet quite ready for their T1.

For much of the country this might appear quite normal, but in the South West we often reach T1 timing in barleys before the end of March. We are now entering what we would call a later spring.

Rhynchosporium continues to be our main concern in the barley crop, with recent frosts having, hopefully, diminished the risk from brown rust.

Winter wheat crops are looking well, but again are quite slow to get away in places due to the cold weather.

As always in this part of the world, septoria is prevalent, even in more resistant varieties, where the true genetic resistance to the disease is yet to kick in as the crops enter the reproductive growth stages.

Free of weeds

On the whole, pre-emergence herbicides have worked well and crops are remarkably free of weeds for the time of year. At the time of writing, I am seeing a flush of spring-germinating broad-leaved weeds such as fat hen and redshank beginning to emerge.

As a lot of these weeds are still emerging as the crop approaches its T1 timing, we may have to consider control between T1 and T2, or delay control until T2 if burdens are not too high.

The winter oat crop is again looking well, but is carrying very high levels of Septoria avenae, apart from the later-drilled crops, which are much cleaner. This disease seems to increase in prevalence with every passing year and, at this time of the year, is of more concern than crown rust.

Spring plantings are well under way, with a lot of spring barley already in. Fodder beet drilling has kicked off, and many are ready to start on the maize crop as soon as the soil temperatures get to where they have to be.

Looking at the weather forecast, this is not going to happen any time soon, with dry, cold weather persisting for a while. Who knows, this could be the year when maize under film actually gives a good economic result, rather than just delivering an earlier harvest.

There is a lot of field work to be done before my next contribution. I hope the weather is on our side for all of it and that we can have a good season, which we all need after the horror story that was 2020.

South: Tod Hunnisett

AICC (Sussex)

Last month, I was talking about the frenzy of activity that was taking place as a result of the weather drying up and the sun coming out. It’s all eased up dramatically now – mainly because everyone is up together with their spring drilling and fertilising, but also because all growth (with the exception of oilseed rape) has come to a sudden stop.

This is not because of lack of moisture – you only have to scratch down 20mm to find it – but because the soil and night temperatures are still very low.

Talking about lack of moisture, there are still areas of the country, particularly the Surrey Weald, that could only be traveled on to apply first doses of fertiliser in the first week of April. We don’t “need a warm rain” just yet.

Less urgency

Recommendations have gone in for first fungicides and plant growth regulators but, given the sudden drop in temperatures, any urgency has lessened. A colleague suggested everyone just park their sprayers up for a week, but that was a week before this will be published.

There is a bit of disease about, with yellow rust hotspots in places, but I’m not panicking too much. I do feel it makes a bit of a mockery of the “teenort” or “teewun” thing though. I have heard of people talking about a “preteenort” or a “teenort and a half”. Oh dear.

Winter barley has finally started to change from ghastly yellow to pristine green. What looked like large areas of barley yellow dwarf virus has also turned green, so I’m guessing that’s OK.

Oilseed rape will be pretty yellow by the time this goes to press – all good stuff. I have to say the best crop of OSR I look after was drilled (against my advice) while I was on holiday at the beginning of August last year. By the time I’m 92, I might know some answers.

East: Ben Pledger

Farmacy (Bedfordshire/Hertfordshire)

By now, most forward crops of winter wheat will have had a plant growth regulator at the growth stage 30 timing, and varieties sitting lower down the yellow rust scoring – such as Skyfall and Kerrin – or where yellow rust has been present, have had a fungicide applied as well.

This has been based on tebuconazole and azoxystrobin, both to eradicate and protect.

The varieties with a more robust rating for yellow rust, such as Crusoe, Siskin and Costello, have been left to do what they’re supposed to be good at. This is with the proviso that if any of them start to break down with rust before the T1 timing, an application of tebuconazole may be warranted.

Winter oats are coming up for their first plant growth regulator of the season, and the recent weather – most notably big swings in temperature – has not been conducive for getting this treatment on in a stress-free manner.

Prohexadione calcium + trinexapac-ethyl will be used in most cases, as it is kinder to the crop than chlormequat.

© Tim Scrivener

Avoid stress

Herbicides and fungicides will all be applied separately to these crops to avoid stress as much as possible. With a relatively short window for these applications and associated intervals between, forward planning of sprayer movements between crops becomes key at this busy time of year.

Most sugar beet in the area has now been drilled, in most cases into moist, fine seed-beds (although a little cool). I’m looking forward to a nice, warm spell, with adequate moisture so that all of the weeds flush at once and herbicide applications on conventional beet are reduced to a standard two-spray programme.

Unfortunately, if the British weather gets its way, the one-off herbicide application of the Conviso system will shine through on standard weed control for a second year, as well as delivering its benefit of weed beet control.