Spring oilseed rape is growing in popularity, being one of the most financially viable spring cropping options. However, getting a robust slug control strategy in place before crops go into the ground, will be key to establishment success.
Where spring OSR is the crop of choice this season, the risk posed by slug damage during establishment could be high, explains Geoffrey Bastard, Technical Specialist at Certis.
“In situations where winter rape has already failed, due to pests or weather conditions, it’s important to assess the soil and make a judgement on what the potential effect could be on the spring crop.”
He adds that despite the recent cold weather, fields with historically high pest populations, may have seen slugs migrate deeper into the soil, only to come to the surface as vulnerable seedlings emerge.
“A wet winter followed by a dry cold period, as we’ve recently experienced, is likely to lead to crops going into cold soils with low moisture levels. As a result, establishment will be slow, and this will leave spring OSR exposed to a very high risk of slug damage.
“Serious losses can occur in spring OSR plants up until the four-leaf stage,” he says. “Therefore, aiming to maximise the growing window to achieve the best possible yield, while minimising the risk from pest damage during that critical period should be a priority.”
Slug control strategy
With so many possible variations in weather for the season ahead, planning a slug control strategy can be a difficult, Geoffrey explains.
“In many places this year, the ground is extremely wet, and growers won’t be getting on to prepare the land any time soon. However, there are slug control steps that can be taken now to mitigate risk over the next few weeks,” he says.
“In line with the latest MSG best practice guidelines, we would always advise approaching slug control from an Integrated Pest Management (IPM) perspective, starting with trapping before cultivating the field to assess levels of pressure.
“If more than four slugs are found per trap, then an application of ferric phosphate pellets as soon as possible after drilling is advised,” he says.
Geoffrey adds that however tempting it may be to delay drilling, this is not advisable as it could lead to a significant yield penalty.
“The focus on drilling timing should be on the weather conditions, rather than being led by a set date.
“Make sure the OSR goes into a consolidated seed bed. Climbing temperatures and adequate soil moisture will give crops the best possible start, and also reduce risk from slug attacks.”
It’s vital to monitor spring OSR from establishment up until the four-leaf stage very closely for pest damage, particularly if crops are developing slowly due to the cold or dry weather, Geoffrey explains.
“Where germination and development are slow, an application of slug pellets can help to keep the slug burden at bay and give the rape time to get away.”