Potato Review

20 POTATO REVIEW NOVEMBER/DECEMBER 2022 PEST CONTROL “In the root veg sector, it’s well-recognised that, on the face of it, cover crops are beneficial for soil health,” he said. “That’s why they’re a key component of the strategy to maintain healthy soils at Elveden. However, I’m also aware that if you get the wrong cover crop, it can proliferate wireworm as well as other pests and disease, which all pose a threat to our yields.” Historically, the use of soil cultivation has been a well-used method of wireworm control for producers, including at Elveden, said Andrew. “By disturbing the soil with tillage or destoning regimes, you’re reducing wireworm populations by physically destroying the larvae and leaving wireworm open to predation. We’ve also found the use of stale seedbeds for controlling weed species in crops that have lost their herbicide portfolio, had the beneficial spin-off of controlling wireworm numbers on those fields. “But, these practices don’t align with the typical principles of regenerative farming. It’s a tricky balance,” he added. “At this moment in time, we don’t know exactly how regenerative practices impact wireworm damage. We’re hopeful the results from the Enigma I research will give us the quantifiable metrics needed to confirm which pest management strategies are most suited to working in tandem with this farming system.” Caution over cover crop usage To manage the threat of unknown wireworm implications, Andrew said Elveden has taken a cautious, data-driven approach to introducing cover crops. “I didn’t want to introduce a blanket policy of cover cropping across the estate that would leave us exposed to pest damage. As a pilot, we’ve been trialling the use of biofumigant mustard in our rotation. This was introduced to keep a check on PCN numbers and has been in place for around seven years now. In August this year, the estate’s agronomist and management team worked with Fera scientists to introduce a handful of half- field cover crop trials to test the impact on wireworm numbers. “We’re comparing mustard, buckwheat, various clover and grass species mixes with a control area. Our ambition is to find a pest management solution which ticks the regen-ag boxes, while also solving near-term commercial problems caused by wireworm damage,” he said. Wireworm infestation Over the past four years, increasing incidences of wirewormhave affected potato yields at Elveden. “It started with our spring barley crops being killed at the two/three leaf stage. More recently a couple of our potato fields have been significantly affected. “The worst incident was in 2021, where we saw wireworm attack nearly every one of our seed tubers shortly after planting. We went through the season expecting an absolute disaster in terms of crop yield. “In the end, we were able to pack elements of the crop for onward sale, but there was a significant proportion that needed to be downgraded. Of course, this was financially damaging – not just in terms of reduced yield but also in terms of needing more graders and in slowing down the speed of grading to ensure quality control.” Wireworm – an ongoing problem Staying on top of wireworm control is a concern for Elveden Estate, with continued investment in regenerative agriculture further complicating the issue, says Andrew. “We’ve considered whether to change the potato variety to help increase pest tolerance, or just grow a short-term crop, or actually not growing potatoes in high risk areas at all. There are loads of questions and no answers, which we’re hoping to glean from our involvement in the Enigma project. “At the moment, wireworm damage has only affected a small proportion of our total acreage, but this is the time for us to find a solution – rather than wait until half of our crop has been blighted.” said Andrew. ELVEDEN ESTATE’S FARMING ENTERPRISE • Largest lowland estate in the UK, covering 9,300ha • Primary focus on root vegetable production, which comprises 500ha of potatoes, 500ha of onions, and 300ha of carrots • In addition, 150ha of maize for anaerobic digestion and 150ha of sugar beet are grown • Combinable crops are primarily used as break crops (includes winter and spring barley, rye, wheat and peas) • A mix of potatoes are grown on the estate for salad, pre-pack bakers or processing, with many sold as own- brand Garden of Elveden produce • A major processing company and four national retailers are also supplied through independent packers • 60 members of staff are employed by the farm business, led by Senior Farm Manager Nicholas Scantlebury as of October 2022 “Our ambition is to find a pest management solution which ticks the regen-ag boxes, while also solving near-term commercial problems caused by wireworm damage.”