The popular and helpful decision support “traffic light” system to aid the timing of both ASTROKerb and Kerb Flo 500 is on the starting grid for the first week of October. Uniquely data can be obtained by growers and agronomists at postcode level. Available on the Dow main web site, the LifeCycle web site and also for Farming On-Line subscribers, this traffic light system works by reporting soil temperatures and soil moisture deficits in every individual postcode area across the UK.
“All growers have to do is to put in their postcode and the system will instantly indicate whether the conditions are appropriate to apply either ASTROKerb (propyzamide and aminopyralid) or Kerb Flo 500 (propyzamide) – just like a traffic light, if red, soil conditions are not right so don’t apply these herbicides; if amber, conditions are getting closer, so be ready to apply and if green, conditions are just right to consider an application. The system is very simple to operate but there is a lot of science and data analysis that goes into it,” explains David Roberts of Dow AgroSciences.
“The usual information for advisors and growers will be on our web site or it will be sent out directly. It is important that Kerb Flo 500 and ASTROKerb are given the best chance to work well. This is particularly so as black-grass control in winter oilseed rape needs to be as effective as possible,” says David.
“To optimise ASTROKerb and Kerb’s performance, there are three areas to consider – soil temperature, soil moisture and weed seed depth. Soil temperatures need to be cooling - around 10ºC and falling, meaning that the herbicide is slower to breakdown and that longer persistence is achieved throughout the weed germination period. This is usually from around early November onwards.”
“Good levels of soil moisture help distribute the herbicide evenly in the top few cms of the soil. So the soil moisture deficit should be down to 50mm and falling. Soils must not be waterlogged or saturated however. Care must be taken to avoid any risk of contamination to water and importantly, all aspects of good Stewardship adhered to.”
Germinating weed seed should not come from any deeper than 5cms as the black-grass would then be germinating from below the zone where the ASTROKerb and Kerb Flo 500 concentrations are high enough to give good levels of weed kill.
David says that if application conditions are right, farmers can expect levels of black-grass control from Kerb Flo 500 and ASTROKerb frequently well in excess of 90%, a level that very few herbicides are currently achieving in any crop.
A sequential approach of using graminicides with black-grass activity such as Laser (cycloxydim), Aramo (tepraloxydim) or Centurion Max (clethodim) before Kerb Flo can boost activity further. Independent trials in autumn 2013 proved how effective a programme of Centurion MAX followed by Kerb Flo 500 or ASTROKerb can be in controlling high levels of black-grass in oilseed rape crops. Applications of Centurion MAX should be made in October followed by ASTROKerb or Kerb in November. There needs to be a 14 day interval between Centurion MAX and any other product. Tank-mixes of Centurion MAX are not being supported this year.
Both ASTROKerb and Kerb Flo 500 have the same conditions of application and the same wide application window of four months, starting from the 1st of October through to the end of January. “Don’t forget that the crop needs to have three leaves. ASTROKerb delivers the same weed spectrum as Kerb Flo 500 with the addition of mayweed species and common poppy. We would expect activity on sow thistle and groundsel too. With quite a few crops suffering early flea beetle damage, pre-emergence herbicides may not have been applied and there could be more broad-leaved weeds around to control post-emergence,” he says.
“Maintaining careful Stewardship of residual herbicides in rape is vital to ensure long term availability of these herbicides and every manufacturer, agronomist and grower should be taking their responsibility seriously,” says David Roberts.
