Pioneering farm employs Mother Nature to confuse crop pests
- Credit: Sonya Duncan
A Norfolk farm is working with nature to combat destructive crop pests - including growing "companion crops" to confuse voracious flea beetles.
Bradenham Hall Farms, in the village near Dereham, is exploring non-chemical solutions to the ongoing problem of cabbage stem flea beetles (CSFB) devouring its oilseed rape.
The crop is an important part of the sustainability of the estate's six-year arable rotation, but it has become increasingly vulnerable to attack since the ban on neonicotinoid pesticides which used to keep the beetles at bay.
So the farm is now in the second year of a trial looking at alternatives including a companion crop of buckwheat, fenugreek and berseem clover, sown at the same time to grow within the oilseed rape crop.
The aim was for the plants to disguise the emerging oilseed rape - disrupting the canopy and masking the natural "plant volatiles" which help the beetles find the crop.
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And it seems to be working. Sticky traps placed within and above the crop found 36pc fewer adult beetles in the plot containing the companion crop, compared to the control plot of regular oilseed rape. This also led to slightly less larvae across the companion crop site.
The farm's agronomist, Andrew Melton of Frontier Agriculture, said there is no "silver bullet" for pest control, and there are many vital factors for the success of oilseed rape including soil moisture, seedbed fertility and variety choice.
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But the early trial results suggested companion crops could play a key role in the farm's sustainable rotation, which also uses spring cropping, "appropriate tillage", farmyard manure and cover crops to encourage life in the soils and the margins.
"You cannot look at things in isolation," he said. "We need to look at the whole rotation holistically, really looking at everything that makes that soil as healthy as it can be.
"For the companion crop, we were looking at that for CSFB to start with, but we are going to get all the benefits for the next crop, and the next crop.
"The soil is more open, it has had lots of roots growing in it, it has more worms at different depths. All the nutrients are more available, you don't get compaction, you maintain the soil moisture at a premium.
"It makes it more resilient. With oilseed rape in the autumn, it is a race - can we get ahead of the cabbage stem flea beetle? Where people have got the stronger rotations, a more integrated approach to pest management, appropriate tillage... all those things give the soil the best chance of being alive, for the crop to compete.
"As a farm we want a lot of life. We don't really want to be using pesticides, because of all those beneficial insects helping everything else in the rotation.
"There are plenty other habitats that the flea beetles enjoy, and they have natural predators, so they are a feed source for something else as well. But you have got to give them somewhere to go, so you need all the green areas and wildlife corridors. There needs to be a refuge for everything.
"You want the whole ecosystem on the farm to be alive. Mother Nature is in charge, so you might as well work with her."
Farm manager David Pike said his team wanted to be "right at the start of something really pioneering" to reduce chemical use on the farm.
The companion crop is being trialled as part of an integrated pest management (IPM) strategy which also looks at drilling dates, organic manure, straw stubble length and cover crops.
Frontier is one of many industry and scientific bodies involved in the national AHDB (Agriculture and Horticulture Development Board) trial, which also has sites in Lincolnshire and Hampshire.
Agronomist Emma Pudney-Filtness said the companion crop grew well at Bradenham, but didn’t affect the oilseed rape's development before it was sprayed off with herbicide in October.
"It has several benefits, but the main reason we were looking into it was to almost distort the canopy so when flea beetles were migrating into the crop they might be distracted by it and go elsewhere," she said. "This is what we were finding with the weekly results."
She said other potential benefits from companion crops include attracting beneficial insects and natural predators of the flea beetles and their larvae, and long-term soil nutrition which could help future crops outgrow the larval stage of the pest.