Careful management to tackle slugs is helping Oxfordshire farm manager Mike Wheeler successfully use an Autocast system to cut his oilseed rape establishment costs, saving an estimated £15,000 a year.
Slug management is important even in dry seasons, he says.
“I had thought slugs were more of a problem in wet years.
But we’ve come to realise dry summers can create difficulties, as the slugs move down the soil profile in search of moisture, leaving you little idea of the size of the potential problem.”
For the past three years, he has established about 230ha (568ha) of oilseed rape, being grown in a heat/rape/wheat/rape/beans rotation, using a purpose-built Techneat Autocaster.
The system sits behind the combine header and distributes a 5kg/5kg mixture of rapeseed and slug pellets to the width of the header.
“It provides greater accuracy than spinning into the standing wheat crop.”
But this season, a new version, with a split hopper and two metering rolls instead of one, is being used.
Mr Wheeler is using 4kg seed/6kg pellets to get more pellets under the straw.
“We then roll, to push the straw down on to the rape to better soil contact.”
More pellets are applied to the top of the straw.
“It needs constant monitoring.”
The system has worked well over the past three years, he notes.
“Apart from the odd very small area we haven’t had any failures, and if required, we can apply another 5kg/ha up to the permitted maximum of 15kg/ha.”
Mini-pellets are used with the Autocast system, partly because of cost, but also because the higher rates allow up to three split applications and more baiting points.
But where the metaldehyde-based minis have not eliminated grazing or where greater duration of activity has been required he has turned to Draza (methiocarb).
There are two exceptions to Barclay Farms’ Autocast strategy – behind barley, because of its early harvest and the straw being too thick, and on the lighter land where the weed flush through the autumn is too vigorous.
In these situations the rape is disced twice, sometimes rolled, and sprayed off before being drilled.
The drill is followed by a further roll, a post-drill spray, and in some cases an application of slug pellets.
“Slug pressure is marginally higher with Autocasting.”
But the extra slug pellet costs and management time associated with Autocasting is compensated for by the savings in overall establishment costs.
“We are saving about £15,000 with Autocast.
With other systems establishment costs go up as diesel prices increase, but ours are not.”
Yields are no different between the two systems, he says.
“Both systems produce an average 27-28cwt/acre (3.5t/ha).”