Including a growth regulator with the imminent phoma fungicide could pay dividends on forward oilseed rape crops this season, according to leading agronomy firm Hutchinsons.
Generally good establishment and favourable growing conditions over the past month have seen crops in a number of regions race through growth stages with some already up to the 8 true leaf stage and growing quickly, says the firm’s technical development director David Ellerton.
“It’s quite a contrast to last year when hardly any PGR was used. Although there is a wide range of growth stages across the country, the bulk of crops are further forward than last year and there’s a much greater need to use a growth regulator this autumn, especially if you’ve got crops at the 4-6 leaf stage and growing quickly.”
But while canopy management is an obvious benefit from using a growth regulator, they also play a crucial role in setting the plant up for the coming season by diverting energy resources into root development, he says.
“Good rooting is far and away the biggest factor in building yield, so getting crops to put down decent roots as early as possible is fundamental to giving it the best chance,” says Hertfordshire-based Farmacy agronomist Jason Noy.
A number of crops in his region are already at the 4-5 leaf stage, and while later-drilled rape is nearer one to two leaves, the recent milder weather and good soil moisture means growth is accelerating and he expects to build PGR activity into many spray recommendations over the next fortnight.
Don’t compromise phoma control
The optimum timing for growth regulation - when crops reach the 4-6 leaf stage - typically coincides with the start of phoma leaf spotting so most growers should be able to combine the two in one application, Dr Ellerton says.
“Tailor the product choice and dose rate to what you want to achieve. Start with disease control then consider whether you need PGR activity with that. If so, the two main options are products containing tebuconazole or metconazole. If not, there are three main options in flusilazole, difenoconazole or prothioconazole-based products.”
Whatever route is taken growers must not compromise disease control by spraying too early for the PGR effect, he warns.
“Optimising phoma control should always be the priority, so sprays need to be applied when 10-20% leaf spotting is visible.”
