No oilseed rape plant is safe from slug attack this year, warns independent agronomist Keith Roberts of KSR Services, as this year's drilling campaign begins in earnest.
While hot, dry weather in July may have knocked slug populations slightly, Mr Roberts explains, there are still plenty of slugs out there and growers must recognise the importance of getting OSR off to a good start in what could prove to be some difficult seed beds.
"Establishment is everything with OSR," he says. "If it doesn't thrive to begin with, it will never be as good as it could have been. Recent rains will have improved seed bed preparation, though if hot dry weather returns it could leave beds cobbly and loose, which opens them up to slugs. Either way, it's best not to take chances and apply pellets soon after drilling."
Mr Roberts points out that rape plants are most vulnerable between emergence and the young plant stage. "High slug populations at this time will have a noticeable effect on the crop. Be careful to maintain the number of baiting points at 35-40/m²," he says, having found Luxan's Trigger 5 [metaldehyde] a reliable and effective control. "It lasts well in the field and proves cost effective."
He advises those using Autocast machines to use an admix of slug pellets and seed, in order to ensure pellets are beneath trash with the seed. This will aid slug control, but, stresses Mr Roberts, farmers may well still need to apply pellets later.
Mr Roberts says that colder weather is also something to bear in mind. "It extends the period of time in which the young OSR plant is most susceptible to slug attack.
"Slugs can eat up to 2.5 times their own body weight in a single feeding session," he points out. "It's not difficult to see how a sustained attack will leave its mark on a newly-emerged crop of OSR."
