Crop Watch: T0 fungicide timing nears for forward wheats

An ever-growing “to-do” list has forced the Crop Watch agronomists to prioritise outstanding tasks, as the increased day length with the passing of the spring equinox will see crop growth increase.

Some forward wheat crops have reached growth stage 30 with thoughts turning to T0 fungicide strategies, providing that sprayers can travel.

Another key debate is fertiliser and whether to merge the first two splits and apply nitrogen and sulphur one big hit. However, that brings increased risk of leaching and reduced fertiliser uptake by crops.

West: Giles Simpson

Pearce Seeds (Somerset)

Giles-Simpson

Giles Simpson

The recent episodes of the Beast from the East have slowed or even reduced growth. Grass growth went backwards by 200kg of dry matter/ha in the last spell.

Little has happened since I last wrote, apart from my neighbour Colin Tizzard training the Gold Cup Winner and one of my customer’s horses winning the Albert Bartlett Novices’ Hurdle at Cheltenham.

The ground has not been given chance to dry out and field work has been very limited, only the really dry ground has been travelable.

See also: Why SDHI fungicide strategies need to change in 2018

Nearly all spring cereal seed is still in the bag and when it does get dry enough to make a seed-bed seed rates will need to be increased. Yield will now almost certainly be affected, as well as delaying harvest.

Septoria is present on older leaves in wheat and is ready to explode when the weather warms up. Dealing with this will be a priority as soon as the sprayers can travel.

We all know in the South West that you cannot give septoria an inch as it will take a mile. Then you will chase it all season.

Contrary to recent articles, I believe septoria needs treating sooner than later. The early drilled crops are coping well with the conditions, but the late-drilled crops will have a lot of catching up to do.

Winter barley crops are struggling with waterlogged soils, they are in desperate need of some nitrogen. Disease levels in barley are generally low.

The winter oilseed rape generally looks good, but the pigeons have hammered it in places in the last couple of weeks. High green area indexes have meant very little nitrogen has needed to be applied so far which is a blessing seeing as travelling would have needed a hover craft.

A period of dry, warm weather is now what we need so that we can catch up with the season’s workload.

East: Marcus Mann

Frontier (Essex)

Marcus-Mann

Marcus Mann

Considering the unusually late, cold blasts, crops don’t appear to have suffered too much. Winter oilseed rape in particular has highlighted the benefit of a good establishment, as the larger canopies with good rooting have survived the cold, wet conditions.

We have now passed the spring equinox and with increased day length there will be increases in crop growth. Large doses of nitrogen are being applied to get enough into the plant for the appropriate growth stages.

It will be important to analyse the growth regulation, particularly in cereal crops. Early plant growth regulator applications will help enhance rooting, result in stronger crown roots and, thereby, reduce the risk of root-based lodging as well as allowing better access to water and nutrients.

Forward winter wheat crops are beginning to reach growth stage 30 and T0 strategies are being discussed.

Yellow and brown rust will have been suppressed, however, the older leaves still harbour Septoria tritici. An application of a multi-site protectant will still have the benefits of reducing these levels and cut the risk of poor disease control in the event of a delayed T1 application.

Oilseed rape is variable with forward crops beginning stem extension. Where light leaf spot and growth regulators are being applied, take the opportunity to top up boron as recent rainfall and wet soils will have reduced its availability.

The colder weather will have reduced pollen beetle activity, but as temperatures begin to reach 15C, keep monitoring backward crops.

With the frustration of a later drilled spring crop this does allow for further use of stale seed-beds and pre-drilling glyphosate on grassweeds.

With colder wet soils, good seed-bed preparation is even more important this year to ensure the crop begins growing from the moment it’s planted.

South: Kevin Knight

Zantra (Kent)

Kevin Knight

Kevin Knight

The big debate has been fertiliser application. Some went too early, some haven’t applied any yet, however, all feel strongly about their point of view and there’s a lot of conflicting advice out there.

The second wheats’ February top dressing of nitrogen plus sulphur didn’t happen. Some are combining the first two splits into one big hit as soon as they can travel. I choose not to use too much in one go as you’ll lose 40% of applied N on average, more in a big application.

Excessive N will either be lost through leaching, locked up or denitrified by microbes. The recovery of N by the crop is closer to 80% with several smaller applications, though you have to offset this against work rate and passes through the crop

If it’s too cold and wet to travel, it’s unlikely the crop will be able to take up much of what is applied, and leaching risk is too high. There is a wide window in which the crop requires nitrogen, so you can afford to be flexible.

The main need is during stem extension through April, which can be split with half early and half towards the end.

Oilseed rape has all had its first top dressing. After concerns of antagonism between ammonium sulphate and boron uptake, I’ve moved to a three way split of crop boron requirements.

One in late autumn as bud initiation begins and one during flowering with the main application (350g) during stem extension. I was expecting to be there by now, but it looks like it will be after Easter.

I’m on the watch for pollen beetle as green bud approaches in the forward crops and a fungicide plus plant growth regulator is planned. There’s little need for a growth regulator yet in late drilled rape.

Some early drilled wheats have leaf four emerged so are now at the right growth stage for a T0. This will be an azole + chlorothalonil in most crops, with azoxystrobin in high rust risk varieties and some second wheats. If mildew is active then I’ll add a mildewicide.

North: Patrick Stephenson

AICC (Yorkshire)

Patrick Stephenson

Patrick Stephenson

If nature had a “pause” button it was certainly pressed this month. As I sit writing this, we have achieved virtually nothing in the past four weeks.

Eddie Jones was accused of not having a plan B in the Six Nations, and I think if he visited any farm in the UK, he would soon learn about plan B, and C and D.

Soil temperatures have barely risen above 3C, which translates into little or no crop growth. I have read with interest the numerous articles stating there is no panic to apply nitrogen at these temperatures.

I am not going to disagree, but there is also the small matter of logistics namely you can only do one job at a time and there are only seven days in a week, so something must give.

Fertiliser priorities must be nitrogen for winter barley, secondly oilseed rape and then second or backward wheat crops. Drilling spring crops is also a priority, because the later they are drilled, then the greater the variability in their performance.

This year it is very difficult to see when and what the starting programme will be.

Early drilled wheat crops look weathered but good. All varieties are carrying some septoria, but rusts appear to be in check. There are no weeds to speak of following good autumn spray programmes.

The questions then are, do growers need to apply a T0? Or will growers be physically able to apply a T0? Leaf 4 is reluctantly appearing and would probably be fully emerged by 10 April.

With that scenario I can see leaf three following very quickly and the best plan is probably a T1 timing being enhanced and T0 missed. Varieties with good septoria resistance ratings will have more flexibility with product choice and timing.

Winter barley crops are now in need of the fertiliser and will receive the vast majority of this as soon as we can travel. Two row barley crops are full of disease and even the normally clean six rows and hybrids have a good smattering.

The first fungicides and growth regulators will be applied shortly after Easter with manganese. The aim this year will be to target a three-spray programme, to try and manage ramularia.

Winter oilseed rape is attempting to stem extend, but the ravenous pigeons and lack of nitrogen are proving a real challenge.

If nature has still pressed the “pause” button by next month’s Crop Watch I will be up to plan Z.