This autumn has turned into an uninspiring start to the cropping season. The warm, wet weather means it’s easy to find phoma lesions in the OSR crops that survived the adult flea beetle.

This week, our agronomists are also considering top-up herbicide applications as the warmer temperatures also shorten the life of residual herbicides.

See also: How to control wireworm in potatoes effectively

North

Patrick Stephenson, AICC (Yorkshire)

In days of old, agronomists would have a slow, stress-free start to a new cropping year. Sadly this is no longer true.

The weekly flea beetle patrol is a futile exercise conducted by agronomists who should know better, and the Monty Python Norwegian blue parrot sketch comes to mind.

If I compare the area my clients planted with oilseed rape 10 years ago to today, there is a 40% decline. I fear we will see a further fall.

Many growers did not use pre-emergence herbicides and have waited to see if there was a viable crop to treat.

The arrival of Belkar (halauxifen + picloram) and Astrokerb (aminopyralid + propyzamide) has enabled us to have post-emergence herbicide options to help control some of the more troublesome, broad-leaved weeds.

I always jest about the email that will arrive in the coming weeks, saying that soil temperatures are now low enough to apply propyzamide.

This always arrives when the chances of applying anything are slim. It is a challenge of matching product breakdown due to temperature degradation and weed size, but I would always prefer to have it applied.

This autumn, the increased rainfall has meant that phoma lesions are easy to find, and many oilseed rape crops with a resistance rating of 6 or below will receive an autumn fungicide.

Cereal drilling

Winter cereal drilling is nearing completion in my part of the world, and it has certainly been a challenge.

The weather is a topic that we British could talk about forever, and once again, it is a topic every farmer is well versed in.

My clients had planned to do some more ploughing this year as part of our grassweed control programme. Unfortunately, as the rainfall increased, so did the area to be ploughed.

Despite this inevitable delay in drilling speed with increased land cultivation, we have managed to get most crops safely tucked up.

The early drilled crops emerged within a week, and this certainly caused much angst with pre-emergence herbicides often being moved to peri-emergence.

Large bursts of rain have also led to some brightly coloured crops as herbicide and seed make contact.

The warm temperatures will mean that products will degrade quicker, so top-up post-emergence applications will be important.

The population of slugs this year is enormous, and I fear applying slug pellets will be an autumn pastime.

Aphids, and the control of them, are always emotive topics in the North. The major vector for barley yellow dwarf virus (BYDV) in the North is the bird cherry-oat aphid, which is not tolerant of low temperatures.

Unfortunately, you must have cold weather to get cold temperatures which, at the moment, are lacking. Crops drilled in September are at risk, and where I am finding colonies of aphids, I’m prescribing a pyrethroid.

Winter beans are now being drilled, and it is vital that these receive pre-emergence weed control programmes.

Propyzamide is the core of the programme, and will include pendimethalin combined with either imazamox (Nirvana) or clomazone (Stallion SynTec).

The 2023-24 cropping year has already given us an uninspiring start. I hope this is not a sign of things to come.

South

Alice Whitehead, Zantra (Essex/Kent)

The weather is slowly shifting to more typical autumnal temperatures as we reach the latter half of October. 

The South East was getting to a stage of soils being almost too dry to drill into in the first couple of weeks of the drilling campaign, with seed-beds lacking the vital moisture required to optimise the performance of pre-emergence herbicides.

Luckily, rain came just at the right time, and in warm, moist soils, crops emerged rapidly.

Cereal herbicide choice has varied depending on grassweed pressures, budgets and following crops, but most include flufenacet and diflufenican, with tri-allate being added into problem areas.  

Cinmethylin has also been used in more challenging situations, to try and get a better idea of the capabilities of this product after a slightly unprecedented first year.

As I write, growers are applying first insecticides to target aphids for BYDV, with top-up herbicides added where required.

Oilseed rape crops that have survived flea beetle adults and slugs are now well established, with broad-leaved weed cleanups complete.

Phoma has been easy to find in crops, with the warm weather providing ideal conditions for infection and spreading. Some forward crops have already received applications of prothioconazole/tebuconazole.

Where grassweeds feature, I am now thinking about applications of propyzamide when soil temperatures decline to 10C or below.

The fungicide will be added to this if not already applied, as well as some foliar boron on lighter land.

Winter beans

Beans are either being drilled or waiting to emerge.

Weed control is proving to be tricky this autumn, following the loss of Extensions of Authorisation for Minor Use (EAMU) for prosulfocarb and straight formulations of pendimethalin, leaving limited product choice.

Pendimethalin and imazamox will be used for fields with problem broad-leaved weeds or oilseed rape volunteers.

Propyzamide will be added to the pre-emergence mix for grassweeds, to be applied within seven days after drilling.

Elsewhere, in other cropping, field brassicas have received their final fungicide and slug pellets before it gets too wet to travel, and asparagus fern is senescing, ready to be flailed as we reach dry or frosty weather in November.

Pumpkin growers have seen good trade during half-term. They’ve had a bumper crop thanks to frequent rainfall during the summer months, while cereal growers were battling with combining.

West

Gavin Burrough, Pearce Seeds (Dorset/Hampshire/Wiltshire)

The dry weather at the start of October that was ideal for cereal drilling and maize harvesting has ended abruptly.

Forage maize yields this autumn have generally been very good. Speed of ripening was slow at the start of the harvesting season, but soon caught up with later harvested crops suffering from eyespot appearing late.

Crops drilled after maize, whether it is cover crop, grass or cereal seed, seem to be establishing well.

Hopefully, the majority of cereal seed has been drilled. Some second wheats have been planted a week or two earlier than originally planned due to the unsettled forecast.

Recent heavy rains have made pre-emergence herbicide applications difficult to plan and apply.

Some of these that missed the pre-emergence timing will be applied early post-emergence, or as soon as conditions allow, with the aim of still applying to the weed pre-emergence.     

Winter bean drilling will be starting as soon as conditions allow.

The reduction in pre-emergence herbicide options useable on winter beans due to the loss of EAMUs on straight pendimethalin and prosulfocarb products is frustrating, to say the least.

Brassica crops

Later drilled brassica crops such as oilseed rape and turnips seemed to escape without too much flea beetle damage.

Instead, they were attacked by slugs and, in some cases, turnip sawfly larvae later in the season than expected. The sawfly larvae have been causing considerable damage in some sizable turnip crops.

Broad-leaved weed emergence in OSR crops not treated with a pre-emergence herbicide has been rapid.

Belkar has been applied where required, or Astrokerb will be applied later in the autumn as soon as soil temperatures are cool enough. Looking at the current forecast, that won’t be for a while.

This will soon cause some concern with OSR on heavy ground, and how late to leave treating the crop before the gate is shut and travel conditions become unsuitable until the spring.

East

Ryan Baker, Frontier (Suffolk/Norfolk)

This autumn has been a contrast to last year’s dry conditions. With average rainfall recorded since harvest, seed-bed creation has been easier and ploughing for autumn cropping more prevalent.

This has allowed a fantastic opportunity to maximise the potential of stale seed-beds after high weed seed return after harvest.

Patience at this time of year is an essential integrated pest management tool, with those who held their nerve being rewarded with a large early October flush of blackgrass ahead of drilling.

With damper conditions, it is important to remember that cultivations alone will not control grassweeds.

These same conditions have also resulted in a haven for slugs, with this autumn already being challenging in both oilseed rape and earlier drilled cereals.

Wetter weather earlier in the year, coinciding with peak spring breeding periods, have increased slug populations going into the autumn.

An increase in seed rate can help to compensate for slug grazing, as well as aiding grassweed competitiveness as the drilling date gets later.

Following the success of cinmethylin last year, many will be using this active for greater blackgrass and ryegrass control in wheat.

With aclonifen and metribuzin also in the armoury, we now have six different modes of action groups for residual grassweed control in cereals.

Aphids

After the joint warmest September on record, aphids are easily found in the earliest drilled crops and on cereal volunteers.

T-Sum 170 – the accumulation of 170 day degrees above a threshold of 3C from crop emergence – will be reached quickly and indicates the likely arrival of the second generation which will spread the virus.

In this region, oilseed rape has also been better than last autumn. Early August planted crops are at wellington boot height.

Later drilled crops have also established well.

Powdery mildew has been prevalent in those early drilled crops. Prothioconazole has activity, but there is unlikely to be an economic yield loss in the autumn.

This autumn also brings legislative challenges for both winter oats and winter beans. Both have been reclassified as major crops resulting in the loss of all EAMUs except for oat seed crops.

So, a friendly reminder that residual herbicides for the autumn are now limited to those found on-label.