Turnip sawfly larvae are back with a vengeance, with high numbers adding to the pest pressure in crops in the South and South West.

There are concerns over the increased barley yellow dwarf virus risk, with winged bird-cherry oat aphids being easily found in winter barley crops.

Elsewhere, very heavy rain and flooding in Scotland has put a halt to fieldwork, and the wetness will encourage slugs, which will need to be monitored, especially in the later drilled wheats.

See also: Early sugar beet yields promising for Cambridgeshire grower

North

Mary Munro, AICC/Strutt and Parker (Perthshire)

The weather has changed spectacularly in Scotland in the past week, and our Indian summer is well and truly over.

Torrential rain and flooding in many areas has brought us firmly into autumn, and has halted field operations for the meantime.

Flying back into Edinburgh after a week away, I was saddened to see straw still lying in the bout and a lot that had been baled, but not yet under cover.

As I neared home, I saw many fields had been drilled in my absence and presume those neighbours will be glad to have got a few more acres of wheat into the ground.

Most of my growers have wheat at 1-2 leaves, which is a common timing for autumn herbicides, though very few will have been applied.

I am nudging up the rate of diflufenican + flufenacet to counter the increase in brome that was widely seen in the run up to harvest, and like to add a picolinafen + pendimethalin product for a broad spectrum of weed control.

Slugs

It is an absolute pain if the autumn herbicides do not get on, and pre-em applications don’t suit everyone.

However, there is a lot of autumn ahead of us so it is far too soon to change plan.

All this wetness will encourage slugs, unfortunately, so renewed monitoring will be required for these later-sown crops.

OSR crops are well up and away now, which is good to see. Once more, we avoided the wave of beetles that took out crops as far north as Yorkshire.

Oilseed rape was all sown into warm, dry seed-beds and slugs were hardly present and the early herbicides applied in good time.

My growers will apply propyzamide later on to tidy up late cereal volunteers and keep on top of brome.

Increasing numbers of growers are establishing cover crops prior to spring cropping. These are providing good ground cover and reducing nitrogen losses over winter.

Once incorporated back into the soil, however, some of the N targeted at the next crop is used to break them down, and it can be a challenge to achieve quick and even establishment of the spring cereal.

I suspect this fact will be shrugged off given the high N levels we have seen in the spring barleys just cut, but it is an area where more knowledge and understanding is required.

East

Becky Finbow, Agrovista (Norfolk/Suffolk)

After a mixed harvest, we are now planning for the drilling season.

With a bit more moisture around than last year, we had the chance to create stale seed-beds, allowing weeds (blackgrass) to chit and be sprayed off in preparation.

Some farmers have taken this window of weather to start drilling, with most of my barley crops now in the ground.

The seed-beds I have seen so far have been ideal – fine, level and well consolidated, but don’t forget to set traps for slugs as they are proving to be a problem this year, as seen in oilseed rape.

Rapeseed crops are large this year due to the early drilling to try and avoid the flea beetle.

I have to say it seems to have worked, with most crops suffering more from slug damage than flea beetle this year.

I think the intermittent showers have kept the flea beetle at bay, evidencing their dislike for wet conditions.

Now we hope this low population will be reflected in larvae numbers, but time will tell.

OSR disease

With forward crops and the warm weather, there is likely to be some early signs of disease – phoma.

Although phoma may be apparent, it is less likely to be as damaging on larger crops as it takes longer for the fungi to travel from the leaf to the petiole and then down the stem.

Saying that, it is still highly likely crops will require an early fungicide such as prothioconazole or difenoconazole.

Where slugs have been an issue in oilseed rape, an application of pellets when the threshold of four slugs per trap has been reached has done the trick and the crop has managed to grow away; many are likely to require plant growth regulators later in the season.

Where blackgrass is now at two-plus leaves and is reachable by spray droplets, clethodim has been applied.

It is likely that when temperatures fall towards the end of the year, it is going to require propyzamide too, so before then it might be an idea to familiarise yourself with the propyzamide stewardship.

The risk of barley yellow dwarf virus is high in emerged cereal crops, following the recent increase in aphid numbers and the ongoing mild conditions.

Vigilance is necessary, and if aphids are found, esfenvalerate or a pyrethroid would be recommended along with some nutrition, if required.

West

Stephen Harrison, AICC/Southwest Agronomy (Avon)

The early part of October has seen as plethora of pests. Cabbage stem flea beetle and slugs continue to aggravate winter OSR.

The unwelcome guests at the all-you-can-eat buffet – otherwise known as winter OSR – have been joined by turnip sawfly larvae. 

The speed at which they can devastate a crop is alarming. At least there in no known resistance to pyrethroid insecticides in the population. I am concerned that the continuing warm weather may result in a further generation. 

Winged bird-cherry oat aphids can easily be found in leaf one winter barley.

The percentage of cereal colonisers is high. Unless predation is high, we will soon have secondary spread and the threat of virus infection. Regular surveillance is essential.

Some failed OSR crops may be replaced by an SFI fallow option.

Phoma

The first phoma leaf spots are appearing in OSR. If rain forecast for later in the week appears, we will start to approach the 10% plants infected threshold. Small plants will be particularly at risk.

Spells of wetter weather and low dormancy have resulted in one of the better autumns for flushes of grassweeds in cereal seed-beds. Glyphosate and shallow cultivations have been employed to avoid overuse of the herbicide. 

Remember that seed return is very high after last season’s disappointing control, so do not be in a rush to drill the worst fields. 

Good progress has been made with the forage maize harvest. In early areas, combining at 30% moisture for crimping is under way. Yields are good, which makes maize one of our higher margin break crops.

Conditions are far too warm for winter bean drilling. Over-early establishment risks winter kill, higher disease levels and lodging.

There is precious little margin in beans, so don’t make things avoidably worse.

Almost all our bean seed is farm saved, and I’m pleased to say that sample results show acceptable germination and no stem nematode.

South

Jamie Swift, Procam (East Sussex)

Following on from the largely drawn-out harvest we saw throughout the country, the arrival of the autumn drilling season has brought with it not only a welcome new beginning, but also a new set of challenges.

Early-drilled oilseed rape crops have had a difficult start due to the high levels of cabbage stem flea beetle larvae finding their way into the stems that are holding affected crops back.

Where conditions favour, OSR crops are also being hit by very high numbers of turnip sawfly larvae, a pest we would like to think would not now be an issue as we progress through October.

Where thresholds are met, I’m not hesitant to recommend control as an infestation can be devastating to a brassica crop in a very short space of time, if left untreated.

Continued mild weather has also resulted in early disease pressure in OSR.

Notably, phoma levels are high in both forward and backward crops, making the decision of where to place plant growth regulating fungicides and where to save prothioconazole-based products an easier one.

Drilling

Cereal drilling is well under way after a tricky time of late managing stubbles. Multiple germinations of grassweeds have highlighted the importance of timing when it comes to seed-bed preparation and pre-planting glyphosate applications.

Early planted winter barley crops are establishing well after being drilled into warmth and moisture, prompting fast establishment.

This pleasing early growth is inevitably accompanied by the threat of aphid and slug attack – the latter causing significant damage currently where seed-beds are anything other than satisfactory.

Wheat drilling has begun, and with the number of problematic grassweeds I’m finding, my pre-emergence programmes will largely be based around Luxinum Plus (cinmethylin) – a product that showed excellent results in its first autumn on the market in 2022.

Trials have shown that stacking active ingredients improves overall efficacy as well as maximising resistance management.

With an important view on resistance, Luxinum Plus used in sequence with other actives such as flufenacet offers a welcome new addition to the overall grassweed battle.

Remember, when applying pre-emergence herbicides, within 48 hours is the optimum whatever the target weed may be but most importantly pre emergence of the weed.