Advice on three possible jobs growers face in September

1) Maximise early season weed control

There’s likely to be growers in two camps this autumn – those that are worried about getting crops in the ground following two difficult autumns and will want to drill earlier, and those more worried about poor grassweed control and are willing to risk later drilling to manage grassweed populations more effectively.

Using the time between harvest and drilling in either case will be important, although those later drilling will obviously have more opportunity to reduce in-crop grassweed populations.

Where cultivations are part of your system, use a straw rake or shallow cultivation to encourage germination of weed seeds or, if you’re using the plough, to reset fields where grassweed control was poor last season.

Later drillers might have time to encourage a couple of flushes before drilling, whereas earlier drillers will likely only have time for one application of Roundup (glyphosate) pre-drilling.

Timing of glyphosate will depend a little on the priority of destroying green bridges for barley yellow dwarf virus versus out and out weed control. For the former, it is better to spray off around 10 days ahead of drilling to make sure no green material is present for aphids to use as a green bridge to the emerging crop.

If you’re looking purely at weed control, just before drilling, or even in with the pre-emergence spray if the label allows, will maximise grassweed control.

In both situations concentrate on application technique – glyphosate is likely to be the most effective herbicide you use all season so don’t compromise efficacy by rushing applications. Check fields for weed type and growth stage and match with an appropriate dose, use the correct nozzles, water volumes and forward speeds.

Where drilling early you’ll almost certainly be locking into higher input spend through the season, including for herbicides. It’s likely you’ll need at least two, if not three, autumn herbicide sprays, for example.

It can be difficult to know what conditions you might face with residual herbicides in early autumn – it might be dry or there could be plentiful moisture so try to choose options that will cover both, and you also want to look for some actives that have longer persistency. With likely higher temperatures earlier in autumn, active substance half-lives can be quite short, which is why top ups of residual herbicides will be necessary.

Liberator (flufenacet + diflufenican) + Proclus (aclonifen) covers those requirements. Aclonifen is proven to remain more active in drier conditions than other actives and has long persistency, along with the diflufenican in Liberator. Flufenacet has shorter persistency but remains a very effective active against grassweeds.

Remember Proclus must be used as a pre-emergence spray – ideally within 48 hours of drilling.

2) Use Magic Trap to monitor cabbage stem flea beetle populations

There are now two mostly distinct camps for oilseed rape drilling – either very early to get the crop established before cabbage stem flea beetle adults migrate into fields, or drill later after peak migration has emerged. Both have shown some success, although it remains a challenging crop to establish in East Anglia.

If you’re in the later drilling camp, our Magic Trap, which is a water trap with a camera attached, is useful to help monitor when the migration window is past. It’s not necessarily a replacement for walking fields, but helps you target when to check more effectively.

Variety choice is key when drilling in September – autumn vigour becomes even more critical to ensure the crop is established and has enough growth to survive any winter weather.

That tends to push towards using a hybrid variety. All the Dekalb range from Bayer have excellent autumn vigour characteristics, plus other traits such as Phoma resistance, pod shatter and turnip yellow virus resistance that are useful through the season.

3) Keep checking beet for disease

It’s been a relatively normal season for sugar beet disease, so far. Thankfully the virus yellows high risk has not materialised because of the spring weather, but alerts for Cercospora have been issued by BBRO in August.

First sprays for foliar diseases, including rust and powdery mildew, will have been applied earlier in the season, and some growers might have also applied a second spray by the time September rolls around.

Where second or third sprays are required – harvest date will play a role in that decision – then Caligula (fluopyram + prothioconazole) becomes an option from 1 September, especially where Cercospora is the main concern.

Containing different actives to those used earlier in fungicide programmes, Caligula also has a seven day harvest interval, which can be useful. Remember there are some restrictions on re-entering fields after application for bolter removal.