We all know black grass control is no longer going to just come out of a can. It requires attention to detail in every aspect of establishment, cultivations, rotation, seed-rates, variety, soil acidity and structure. Only an integrated approach will provide sustainable control.
On several occasions soil testing this summer, bad blackgrass patches have corresponded with areas of the field with a low pH, poor soil structure or poor drainage. Although stating the obvious, soil condition can so often be overlooked with the flurry of activity at this time of year. Time to dust off the spade, look at the soil profile and get some soil samples analysed.
Those growers that have created stale seedbeds this year have been rewarded with good germination of blackgrass seeds that can then be killed cost effectively with glyphosate pre-drilling.
On very close inspection, fields left untouched since harvest often have a large population of germinated blackgrass, again this needs a glyphosate treatment.
Attention is also focusing on creating a final seedbed that is conducive to maximising
the efficiency of any residual active ingredient. Rolling seedbeds will also be helpful
if the weather allows.
All Blackgrass programs will be based around flufenacet pre-emergence at 240
g/ha. Tri-allate, CTU, prosulfocarb, DFF, pendamethrin will be added to the
programs depending on the individual circumstance.
Pre-emergence herbicide sprays are now complete on oilseed rape, although drilling method (seed depth), catchy weather, and workload constraints have limited the area sprayed.
Post-emergence applications need to be timed as soon as possible after cotyledons are
at the fully expanded stage. Products based around metazachor with dimethenamid-p
or quinmerac are suitable depending on the weed spectrum. Blackgrass levels in the
early-drilled OSR crops are causing some concern, and treatments are required to
ensure plants are not too large for propyzamide application later in the year.