Too many farmers are desiccating their oilseed rape crops too early and are missing out on up to 0.66t/ha of extra yield, warns one consultant.
“Workload pressures and the overwhelming desire to get harvesting means crops are often being sprayed at least a week before they should be,” says Hutchinson’s technical development director David Ellerton.
But just like swathing, going in too early with the glyphosate will do more harm than good.
Each day of seed filling lost reduces seed yield by 1-2%, which over a week equates to 0.33-0.66t in a 4.5t/ha crop. Since most oil is accumulated during the second half of seed fill, earlier than ideal spraying can also compromise oil content.
Independent trials in Sweden found delaying desiccation and harvest by just four days increased yield, says Monsanto’s NW Europe OSR project lead Kuldip Mudar. “Its oil content also rose by 0.7 percentage points.
“Early spraying will not bring forward the harvest. It will just take longer for the crop to dry down,” says Mr Mudhar.
Dr Ellerton adds: “Sometimes I’ve seen it ‘freeze’ the crop rather than working with it to improve dry down.”
In conclusion, Dr Ellerton believes not going too early will pay dividends. “Pod sealants and shatter resistant varieties can markedly reduce any extra risk of seed losses this may entail.”