Rapidly emerging weeds are continuing to test our Crop Watch agronomists and slugs are coming out in force.
Blackgrass was romping through oilseed rape fields, but some pre-emergence treatments were managing to hold it back, said ProCam agronomist Nick Brown from Buckinghamshire.
It was still too warm for propyzamide, so the only option for thick blackgrass stands was to try and reduce populations using a graminicide, he said. “Aramo (tepraloxydim) is the only one worth using. I have already had some excellent results, but it does need a water conditioner adding to the tank first and needs applying in a medium to fine spray at a maximum speed of 10kph if it stands any chance of working well.”
Slugs were starting to appear in crops following oilseed rape, but thanks to good seed-beds little seed hollowing had occurred. However, leaf grazing would be significant where there were high populations, he said. “I am advising the use of pellets in these situations before emergence to reduce the slug population and subsequent grazing.”
Yorkshire AICC agronomist Patrick Stephenson reckoned weeds would be significantly harder to control this year. “Last year early post-emergence sprays of pendimethalin and diflufenican provided excellent control of annual meadowgrass and most broadleaved weeds. However, this year could be different as emerged broadleaved weeds and tillered meadowgrass are different beasts.”
Brian Ross, Suffolk agronomist for Frontier Agriculture was hearing reports of bad blackgrass problems in oilseed rape and poor performance of traditional fop and dim chemistry. “This is worrying as we will have to use residual products earlier than normal. Carbetamide will be first and it is vital recommendations are followed as the potential for damage is higher when going earlier and in warmer conditions.”
Propyzamide may need to be applied after this one soil temperatures had dropped, he added. “This approach will be costly, but some blackgrass is very aggressive.”
In Shropshire, persistent rainfall from Friday (1 October) through to the following Monday would probably halt drilling for several days, said AICC agronomist Bryce Rham. “We need two to three weeks of dry weather to allow those that haven’t finished to get drilled up.”
All oilseed rape had been planted and early-sown crops were at the six true leaf stage, he added. “Later-sown crops are at cotyledon and downy mildew is appearing on the cotyledons of early-sown crops. There are no signs of phoma.”
Winter barley drilling began two weeks ago and most forward crops were at the two true leaf stage, said Mr Rham. “We will start applying post-emergence products this week and there are no slug problems, yet.”
Video: Patrick Stephenson assesses rapidly emerging grassweeds