According to their labels, products containing propyzamide (as in Kerb Flo and ASTROKerb) can be applied to oilseed rape from the 1st of October. However to utilize their residual activity and thus optimize the activity of these herbicides against blackgrass and other grass weeds, soil temperatures need to have fallen below 10ºC whilst soil moisture should be sufficient but not saturated. With some regional variation soil temperatures are around 12-14 ºC at the moment so we have a few weeks to wait. From past experience and under normal circumstances, conditions usually become suitable for applications from around Bonfire night, 5th November, says Tom Sowerby, technical specialist for Corteva.
Available from late-October, Corteva Agriscience will go live with its weather data decision support system to help optimize application timings of ASTROKerb (propyzamide and aminopyralid) and Kerb Flo 500 (propyzamide). Whilst the graphics this year reflect Corteva blue branding, all the familiar and relevant information on this system is still available. Data is available to a postcode level, based around a traffic light graphic and the support system helps application decision making. Mr Sowerby explains that when the traffic light shows red, soil conditions in the postcode area are unsuitable, so these herbicides should not be applied because propyzamide will breakdown more rapidly at higher soil temperatures and blackgrass control will be compromised. If the traffic light shows amber, conditions are getting closer, so you should get ready to apply and if it goes green, conditions are broadly suitable and are becoming right, so you are advised to go and check your individual fields. Tom stresses that whilst this is not a definitive instruction to go and apply the herbicide, it is a strong indicator for growers to look carefully at conditions for any particular field or farm.
The decision support system (DSS) also indicates wind, rainfall and the national soil temperature summary to help growers and advisors plan their spraying workload more effectively.
The DSS is available 24/7 on the Corteva main web site (https://www.corteva.co.uk/tools-and-advice/kerb-weather-data.html) and also on the Farming On-Line web site. For the first time it will also be available as an App for both android and iphone on the new Corteva’s mobile arable App which will be launched at Croptec on 28-29 November in Peterborough, says Tom.
Mr Sowerby explains that this tool is a guide to growers and advisors to help them identify when conditions are suitable for applying propyzamide in their locality. Growers and advisors enter their postcode and the system indicates the current status of criteria that influence the decision to make herbicide applications containing propyzamide in their postcode area.