Welcome to the fourth and final edition of Kerb Weather Data for this autumn. This report will provide timing guidance for applications of propyzamide containing products (Kerb® Flo 500 & Astrokerb®) to oilseed rape.
It uses the 'popular traffic light system' red “conditions unsuitable”, amber “get ready/be prepared” and green for “go”.
Over the last few weeks we seem to have had weather from all four seasons, brief periods of cooler weather followed by mild, wet and windy conditions as multiple storms travel across the country.
Air temperatures therefore have been in a period of fluctuation, with information from our internal weather stations showing temperatures alternating anywhere from 3.4°C – 16.6°C, averaging at 7.4-10.6°C, depending on where you are in the country.
Soil temperatures, especially when measured at 30cm are less susceptible to this climatic variation and have remained between 4.08°C and 8.04°C throughout the country.
We are therefore still in a suitable period for application of Kerb Flo 500 and Astrokerb.
Cooler soil temperatures slow propyzamide breakdown and ensure roots are exposed to propyzamide for as long as possible, optimising control.
Oilseed rape crops are continuing to look well and range between six and nine true leaves (GS16-19). With lower levels of cabbage flea beetle than in previous years and a decent crop price, this crop is definitely worth protecting to maximise its yield potential.
So if grass weed control is required but not yet applied, then an application of Kerb Flo 500 or Astrokerb is still worthwhile. Corteva Agriscience only supports 1 application of Astrokerb or Kerb Flo 500 per season per OSR crop, which can be applied up to 31st January. Belkar® may still be a valuable addition to this mix to extend the broad-leaved weed control but applications of this product can only be applied until 31st December.
Soil conditions have deteriorated in many areas since our last bulletin so it is important to consider applications on a field by field basis, with specific information available through our Kerb Weather App.
Remember Right Rate, Right Conditions and Right Time.
Application timing
- Consider individual field conditions before making an application.
- Avoid applications on waterlogged soils, or when heavy rainfall is expected within 48 hours of application.
- Many crops will have received a frost recently and are likely to be well-weathered making them suitable for treatment. However, avoid situations where crops remain stressed, i.e. due to poor soil conditions, nutrient deficiencies and CSFB damage.
Weather conditions
- Is a dry leaf required for application?
- The propyzamide active in Kerb Flo 500 is soil-acting, so spraying wet weeds at run-off or light rainfall after application is not an issue.
- Ideally, the rainfastness of Astrokerb is 1 hour for the aminopyralid element. Spraying on a drying leaf is preferred; if rainfall falls within 1 hour and causes run-off, efficacy may be reduced.
- Applications in the frost
- Kerb Flo 500 may be applied in frosty conditions but avoid application onto frozen ground where subsequent rainfall could result in run-off.
- For Astrokerb, please ensure frost free leaves for the target broad-leaved weed.
- Applications in the snow
- Similar to frosty conditions, for optimum grass weed control, propyzamide should not be applied to frozen ground and spraying on snow increases the risk of subsequent run-off as the snow melts.
Frost may have already started to encourage some companion crops to die off naturally. Growers may also consider their purpose now redundant, see below for information on how our product offerings can aid in this process.
For more advice regarding application of propyzamide, please call the technical line on 0800 689 8899, which will be manned throughout the Christmas period, except Bank Holidays.
Corteva Agriscience would like to take this opportunity to wish all our readers a very Merry Christmas and a happy, safe and prosperous New Year. Thank you for your continued support.
The map below shows soil temperatures and moisture-deficit information for your region. Please note that the soil temperature value for 30cms rather than 10cms is referenced as the results are less variable and more reliable.
