It's vital to pay as much attention to detail to the establishment of OSR as to cereals, believes Hutchinson’s technical manager, Dick Neale.
"Gross output might be the starting point for variety choice but resilience against CSFB grazing and larval infestation, resistance to virus, disease, lodging and pod shatter all need equal consideration," he comments.
With pyrethroid insecticides becoming increasingly ineffective against CSFB and peach potato aphids, cultural controls are brought into sharper focus, says Dick.
"Variety, seed rate, establishment technique, seed bed quality and placement nutrition are all important but it’s also important to take a step back and review the whole farming system. It’s easy to fall into the trap of treating individual issues in isolation, as and when they arise, without considering possible impacts later in the crops life or within the rotation, “he adds.
Moisture in the seedbed is key consideration for OSR establishment and consistent availability of moisture is a frequent problem during Aug, says Dick. “The amount of water available for germination and establishment is influenced strongly by seed-to-soil contact, so the aggregate or “clod” should be no bigger than a key on a computer keyboard.
"Any bigger and the percentage of seed establishment declines significantly," he points out. "Drilling depth is also a key consideration, Germination declines sharply in seed sown deeper than 50mm and establishment vigour is impacted from 25-50mm depth.”
While seedbed quality and adequate moisture can be managed to some degree, for many growers the decision whether to continue growing OSR has been influenced by their experiences with CSFB. Hutchinsons have investigated which factors can impact the crops ability to survive CSFB attack and have discovered a number of practices that stack the odds in the crops favour.
“Its best to avoid sowing the crop into drying seedbeds with a continued dry and warm forecast and no deeper than 50mm. Minimal soil movement reduced adult feeding and the presence of chopped straw, applications of FYM digestate or slurries can help eliminate adult feeding,” says Dick.
“Placement of fertiliser, preferably phosphate-based (such as micro granular Primary P) offers significant improvements in establishment and growth away from feeding pressure. Volunteer cereals also reduce feeding, but this only works in strip-sown situations where the seeded strip is clear of volunteers and moisture is not limiting.”
The work also shows variety choice can have a significant impact. The new hybrid variety LG Arrow has proved particularly resilient to adult feeding and larval invasion and Clearfield varieties have proven particularly resilient to adult feeding.
“Seed rates should be increased by 50%, for instance 75 seeds m² for hybrids and 100 seeds/ m² for conventionals. There’s no advantage to sowing more than 100 seeds/ m² for 5kg/[email protected] TSW) when seed is accurately sown within the top 25mm of soil, “he says.
The zinc ammonium-complex seed treatment Radiate, offers rapid emergence and vigour improvements when used in conjunction with foliar phosphite applied from the four leaf stage, advises Dick. “Mixing 10kg/ha of technical grade urea with seed (to apply a total of 13-15kg/ha) has proven very effective, but only in the presence of adequate available phosphate.”
The practice of planting companion species, focussed on CSFB from the crop, have proved inconsistent, he adds.