By Jonathan James for November’s issue of South East Farmer
Following the long hot summer of 2026 and with a “Super El Nino” developing that will undoubtedly impact global weather, and unlike in 1976, the UK weather seems reluctant to succumb to the vagaries of autumn just yet. Apart from the weather, farming seems to be facing an unending plethora of challenges, from escalating production costs and political ambivalence to the more tangible pest and pestilence types; the latter have been testing in almost all crops this year.
It seems odd to be writing well into October and still be concerned about the lack of any significant rainfall. Early drilled crops initially had variable establishment due to dry seedbeds, but the little bit of rain we have now had does mean seedbeds and establishment have improved significantly.
With the rain, there will likely be a flush of weeds, however residual herbicides should now be effective. As the drilling campaign comes to a close, it’s time to consider herbicide top ups for grass weed control and to monitor gout fly and aphid migration through to the winter.
With the favourable conditions through October, most crops have received a pre-emergence herbicide and are now looking at getting residual top ups. There is no doubt that where black grass and rye grass are a problem, stacking residual herbicides will give far greater control and persistence. Given the recent warm, dry conditions, the persistence of most herbicides will be limited, and it is therefore important that a further top up is used to achieve maximum control.
Residual chemistry typically only works on the root and shoot of the weed within the top 10 to 20mm of soil. It is therefore important that it is applied before the weed emerges, so don’t delay any further application or control will be compromised. If black grass or rye grass is past the one leaf stage, then a contact herbicide will likely be required, providing populations are not resistant.
Given the pressure last autumn and spring, aphids and barley yellow dwarf virus will be fresh in people’s minds. It is important to make sure we are all monitoring for aphids before spraying, although at present it is relatively easy to find winged aphids in early emerged crops.
Where populations are high, aphicides should be applied imminently. In the case of low populations, then typically the T-sum calculation of 170 degree days (dd) should be followed to monitor the development of the second generation of aphids that tend to cause most of the damage. Given recent temperatures, though, 170dd will be achieved very quickly. After applying an insecticide, assessing control will be key. Last spring there were a lot of grain aphids present, and these have developed a pyrethroid resistance and may not be controlled if found in the crop. Typically in the south we tend to find more bird cherry oat aphids, which should be controlled with a pyrethroid application.
Oilseed rape crops seem to be slowly getting away now with the recent rain and attention will move onto propyzamide timing where required. For optimum control, soil temperatures of 10 degrees at 30cm and declining, with adequate soil moisture, are required. November tends to be when this spray window opens. Where aminopyralid is used in the mix, a dry leaf will be required for successful control of weeds such as poppies, thistles and mayweed.
Although there is little evidence of phoma expressing itself yet, crops will need to be monitored closely this season because many varieties rely solely on RLM7 genetic resistance, which has shown signs of breaking down.
