Four insights into how to get crops off to a good start in the west

Crop Progress

Harvest has been stop-start in the west, as this is written a week before the August bank holiday. What has been cut I think has been around average – nothing spectacular – but as prices are good most farmers seem generally happy.

The lack of sunshine and the hot spell we had earlier on in summer have probably curtailed yields.

While some oilseed rape has been drilled into moisture and seemingly ideal conditions, the slow harvest, where fields haven’t been cut or there hasn’t been the chance to bale straw, has frustrated some attempts to get the crop established. But I think there’s more to go in.

Gareth’s agronomy tips for September

1. Attention to detail matters for later oilseed rape plantings

If you’re going to drill oilseed rape in September, then attention to detail becomes even more important. Traditionally we are a bit later establishing oilseed rape in the west, as we tend to be a bit wetter, and the ground is generally good so we don’t get our cereal harvest, especially wheat, off too early. So establishing oilseed rape in the first or second week of September isn’t late for us.

But attention to detail is everything. It starts with doing everything, from correct variety choice, retaining seedbed moisture, keeping slugs off, using starter fertiliser, etc., to help get it up and away quickly.

While autumn vigour is obviously important for a variety drilled in September – and where hybrid varieties are even more valuable – don’t forget to look for spring vigour too. If you’re worried about flea beetle think about that too, how will it grow away in the spring? If you can get some good early spring growth it can take the crop away from pest damage there as well.

Varieties, such as DK Exstar, which is part of the Dekalb Establishment Scheme, is one such variety that offers both rapid autumn and spring development, along with a good combination of disease resistance.

The Establishment Scheme helps take away some of the risk from growing oilseed rape. If you’ve drilled an eligible variety by 20 September, registered through your seed supplier by the end of the month, if it then fails to establish in 6ha or larger blocks by the end of October you will be credited £100/bag.

2. Think about what you’re trying to achieve with stubble management

The first step to making the most of the gap between harvest and the next crop is knowing what your enemy is. Hopefully you’ve either had a good look around fields before harvest to understand weed pressures or have good historical information as weed species will have a big impact on how you manage the land culturally.

Brome is a classic example. If your primary concern is great or sterile brome it needs darkness to help break dormancy, so you might want to tickle the soil surface or spread chopped straw to cover seeds and create the environment to break dormancy.

If you’ve got soft, meadow or rye brome that that needs light to break dormancy, so you don’t want to do anything with that directly after harvest for about a month.

It’s all about thinking about what you want to achieve – the weeds will come up eventually, so what you’re trying to do is avoid it coming up in your wheat or barley crop, and being able to control it when easier with Roundup (glyphosate) or cultivations.

Black-grass and ryegrass are similar to sterile brome, and some shallow soil movement to create a seedbed can help it germinate. But think about soil movement – the more you move the more weeds will come up, so if you’ve done a good job with your stale seedbed, try to move as little soil as possible when drilling.

Equally don’t discount the plough where needed. It’s still a useful tool to use. Soil experts tell me that if your soil is in good condition, when you plough it doesn’t completely reset the soil structure and soils in good condition recover more quickly. I wouldn’t be using it regularly, but if I’ve had a disaster with weed control and need to get rid of this and start afresh sometimes it’s the sensible option to use.

When it comes to spray off with Roundup, don’t use more than two applications and mix it up with cultivations to help reduce the risk of resistance building. Think about the weed you have, its growth stage and use the appropriate rate of Roundup. It will vary depending on the weed and growth stage – invariably the bigger it is, the more active you will need to control it.

3. Understand the trade-offs for September drilling dates

The earlier you sow the higher the weed burden will be, and also the disease and barley yellow dwarf virus risk. Offsetting that will be if everything goes in your favour earlier drilling is likely to have higher yield and also helps spread workloads.

Drilling later undeniably means less weeds, but also a less competitive crop, lower yield potential and perhaps poorer drilling conditions. Understanding the trade-offs and mitigating them is important.

If you are going to drill in September, then prioritise your cleanest fields or those with least grassweed pressure and think carefully about variety choice – avoid setting yourself up for disease control problems by drilling a Septoria-susceptible variety.

The other thing is don’t drill a large area if you’re worried about grass weeds, if you can’t spray it, as in the current situation you have to rely on residual herbicides, some of which you can’t put on post-emergence and others that work less well the later you apply them. That might mean thinking about getting some help in from contractors or neighbours so you can drill and spray it.

I do think off the back of last year where the pre-emergence Liberator (flufenacet + diflufenican) and Proclus (aclonifen) was not always applied, but where it was it worked really well, will focus minds and help growers think about the bigger picture, rather than the cost of a contractor.

If you have bad grass weeds, the Liberator + Proclus mix is definitely a good base – the aclonifen helps with ryegrass, black-grass and bromes, bringing more persistency and seems to be less affected by dry conditions. It doesn’t move much in the soil, and is mostly taken up by the shoots growing through it rather than needing to be washed down into the soil profile.

Think about the rest of the programme – there are places for prosulfocarb and tri-allate – and try to mix your modes of action rather than just piling on more and more flufenacet.

Adding aclonifen and metribuzin bring different mode of action away from flufenacet, tri-allate and prosulfocarb, which are all the same mode of action group.   

4. Finish off potato blight programmes

Remaining potato crops are coming towards harvest, but make sure any remaining blight sprays have tuber blight activity, especially for crops that are going into longer term storage.

Infinito (propamocarb + fluopicolide) makes a good choice for this among the very limited options available.