Agronomy Update - October 2020

Due to the earliness of this year’s harvest, last month’s bulletin covered a lot of what is traditionally covered in the October edition. We enter this month in a completely different position than last year as the recent forgiving conditions have meant the harvest was completed relatively quickly, and field preparations began with enthusiasm. Unfortunately, in some cases the dry conditions reduced the effectiveness of some stale seedbeds which may put extra pressure on pre-emergent herbicides this autumn.

As it stands today, OSR, Linseed and Turnip crops are well established, and many winter cereals have been drilled with pre-emergence herbicides applied. Areas with large black-grass populations are likely to be drilled later in October to reduce black-grass pressure. Seed should be drilled into fine, firm and moist seedbeds and rolled prior to applying herbicides. The pre-emergent herbicides work best in moist soils and at higher water volumes.  

Jonny Oosthuizen - Bartholomews Agronomist

A connected approach when it comes to herbicide application is important. Weed pressures are as such that in most cases a pre-emergent followed by a post-emergent herbicide program isn’t enough to keep the weed populations from increasing year on year. Obviously product choice is critical, but attention to detail with regards to seedbed preparation, adjuvant use, cultural controls, nozzle choice, water volume, weather conditions etc must be applied. This will optimise the efficacy of the application and reduce the pressure of resistance building to the active ingredients.

Turnip sawfly larvae seem to have been a bigger issue on turnips and OSR than the feared CSFB - again quite a contrast to 2019. Treatment may be necessary depending on the population numbers and crop stage, thankfully there is no known insecticide resistance to Turnip sawfly larvae. Slug activity should be continually monitored until the crops are sufficiently grown and out of harm’s way.

With OSR crops already looking considerably better than last year, this month may see some initial Phoma infections which can be treated with the appropriate fungicide product perhaps in conjunction with some foliar nutrients where necessary.

It’s exciting to see lots of cover crops established with some interesting multi-species mixes being tested. The understanding of how the use of these crops improve soil health is growing and is critical with regards to the vast and ever more important topic of carbon management.