Crop Watch: Drilling woes and OSR propyzamide sprays

With no let up in the wet conditions, the wheat drilling headache continues, with fears growing that crop will not get drilled.

For those crops in the ground, barley yellow dwarf virus could be a real issue if there is a mild winter, being the first autumn without neonicotinoid seed treatments.

Soil temperatures have now reached a level that propyzamide can now be applied to some oilseed rape crops, providing the sprayer can actually travel on fields.

South: Stan Harrison

Zantra (Kent)

Stan Harrison

In nearly 20 years of agronomy, I can’t recall an autumn quite like this one.

Field conditions went from bone dry in September to waterlogged for the most of October and so far in November.

See also: How to sample your grain on farm to get the top price

As a result, growers in the South East have been forced to compromise their drilling plans, taking any available opportunity to get more crop in the ground.

Plans are now being made by some for spring cropping on fields, which are unlikely to be drilled before the latest safe sowing date.

Remember that the requirements for safe and effective herbicide use remain – most residuals require a “covered seed depth” of about 30mm.

Seed-beds need to be checked if there is any doubt and, if necessary, herbicide applications delayed until after crops have emerged.

With the demise of Deter (clothianidin), one of my main concerns this autumn is barley yellow dwarf virus (BYDV) transmission by the bird cherry oat aphid and the grain aphid.

This can happen by both wingless and winged forms of these aphids.

Wingless aphids can walk into cereal crops from nearby grass or volunteer cereals (a reminder to consider control stubble weeds where appropriate).

Winged aphids can fly into crops from further afield. Initially, only a few plants become infected, but once settled, these aphids reproduce quickly and their progeny will spread to neighbouring plants as second generation.

Aphid threat

Controlling this second generation (which remains a threat even now) is a key component of BYDV management, as this is when the disease affects larger patches.

Development of the second generation can be roughly forecasted by accumulating daily average air temperatures above a baseline of 3C.

It takes about 170C day degrees for the second generation to be produced.

Day degree calculations should start from the day of emergence for the crop.

Subsequent checks should be made starting around one week after any pyrethroid application.

West: Giles Simpson

Pearce Seeds (Somerset)

Agronomist Giles Simpson

Giles Simpson

I had hoped that since the last time I wrote the weather would have given us a chance to get drilled up.

Unfortunately, we have only had six dry days in the past four weeks and these came in two three-day breaks.

This hasn’t been enough to drill any significant acreage.

There just weren’t enough plough and power harrow drill combinations to go around.

I would estimate that we are only 40% drilled up at best and only 5% of this acreage has been sprayed.

There just hasn’t been enough of a break in the weather to allow spraying to be done.

I would say that if we don’t get a serious break in the weather now, there won’t be any more drilling done this autumn or spraying.

Luckily, I don’t have much ground that has been drilled where blackgrass would be a problem, but I am not looking forward to next spring crop walking on unsprayed fields.

I would think weed control may be a problem, as well as the effect of barley yellow dwarf virus in crops that are going to be thin due to slugs and poor plant stands.

The crops that were drilled early do look well considering how wet the ground under them is, and, in general, they are the 5% that have been sprayed.

Those drilled in the past couple of weeks are struggling in waterlogged ground and the slugs have been active on some, but it’s too wet to travel.

OSR crop losses

Oilseed rape crops have taken a hammering and I would estimate that 60-70% have been lost.

On a brighter note, the maize harvest has finished and, generally, yields and quality were good.

Most was cut without causing too much soil damage; there will be some fields that have taken a pounding and some remedial cultivations will need to be taken probably in the spring.

I would encourage everybody to make sure the fields don’t cause any runoff over the winter.

Looking ahead, spring cropping plans need to be made and seed ordered in readiness for a larger spring cropped area.

And by the time I write again in the spring – and if you want to be really optimistic, we will have had an election – we’ll be able to plan for the future. We can only hope.

North: Patrick Stephenson

AICC (Yorks)

Agronomist Patrick Stephenson

Patrick Stephenson

The competition between agronomists at the moment is “how much rain have you had?”

In North Yorkshire, since 22 September (also now known as the equatorial rainfall season) we have had more than 320mm of rain.

The next question is “how much have you got drilled?” This is a more delicate question, as this can vary from nothing to almost complete.

Across the board we are probably near 60-70% drilled.

At this point, I must add that drilling does not mean emerged or survived, so my expectations are not great.

Winter barley is now a delightful shade of yellow and the Dulux colour chart covers most of the yellow options.

Spraying is complete on these and is partially responsible for some of the yellowing.

I appreciate that the aphids may still be flying, but credit to them if they can survive the wind and the rain.

On a more practical point of view, we will reassess the risk in the spring, but with the worst winter for 30 years being trumpeted in the press, who knows?

Oilseed rape crops are also exhibiting a nice pallet of colours, these more closely aligned to the purple range.

Those crops that are well established will be due a propyzamide application and, according to Corteva, they can be applied now.

This is the first time I can remember when the magical soil temperature of below 8C has been reached in late October.

However, it is no surprise that this coincides with the only time in as many years we can’t travel.

OSR spray

This will remain on the “to do” list, and with an explosion in phoma, a fungicide will be added.

It is with sadness that I announce that flea beetle can swim as the rain has not deterred their activity and the casualty list of abandoned fields grows.

Drilling wheat has really become one of the trials of the job, with every field a unique challenge.

We do have good crops and fields that have received a full herbicide input.

Unfortunately, that is not the norm, and even the thought of applying a herbicide brings on a migraine.

Late drilling will lead to a lower blackgrass germination, but not zero.

Most pre-emergence sprays have a label clearance to the end of January, so if the chance arises and the crop is present then an application is likely to be beneficial. 

Growers are already asking about the last safe sowing date in the North – nearly all winter wheat varieties will be safe to sow up to the end of February.

Agronomists of a certain age can remember similar years and, unfortunately, they are like toothache.

My advice, for what it’s worth, is keep drilling if conditions allow, leave headlands and push up seed rates.

Winter beans are now coming through and look well. If you have winter beans to drill, please be aware that they do not like water and ploughing in on a saturated field is not good.

That brings us to spring alternatives, and spring barley will be the most common and “go to” crop, so to start sourcing seed now is probably very wise.

Everything else carries some degree of health warning, and although all can be profitable, they do require some element of good fortune.

My highest-risk crop would probably be spring oilseed rape, but none are perfect.

East: Marcus Mann

Frontier (Essex)

Agronomist Marcus Mann

Marcus Mann

Autumn 2019 has certainly been challenging, with a large area of drilling still remaining.

Thanks to a drier September, soils still have a way to go before reaching field capacity.

This provides an opportunity to continue drilling and, as the season progresses, seed rates are being adjusted to individual field conditions at the time of drilling.

Slug pressure has increased and treatment has been dependent on both seed-bed conditions and previous cropping, with oilseed rape proving to have the highest pressure.

With slower emerging crops, this will be a season to benefit from seed dressings such as Vibrance Duo (fludioxonil + sedaxane) along with foliar applications of phosphite to encourage quicker establishment and rooting.

Winged aphids are being found within emerging barley and wheat crops.

AHDB figures show 18% of bird cherry oat aphids are carrying barley yellow dwarf virus.

This result could lead to significant BYDV levels if we have a mild winter, as problems with spread arise when the second-generation offspring of the original winged colonisers are produced.

T-sum

This is usually the generation that begins moving significantly away from the plant originally colonised.

Roughly, this begins when 170C day degrees above a threshold of 3C have accumulated.

T-sum calculations should begin on the day of emergence for untreated crops and one week after application of pyrethroids.

Winter oilseed rape areas have continued to condense.

A later-than-usual cabbage stem flea beetle migration period has led to crops being grazed off and stunting growth.

This has brought further issues with phoma, which has reached threshold due to recent wet weather.

Yield losses will be greater from early infections on smaller plants, as the pathogen has a shorter distance to travel before developing in the stem.

Now is certainly the time to decide on the viability of OSR crops as treatment will be necessary.

On smaller crops, avoid fungicides with any growth regulation (such as metconazole and tebuconazole).

Soils are beginning to reach temperatures conducive for propyzamide applications (less than 10C) and applications will begin in oilseed rape over the coming weeks.