Potato Review

20 POTATO REVIEW JULY/AUGUST 2021 SPROUT SUPPRESSION ‘Mint oil costs too high’ Keeping a lid on storage costs is the signi cant factor in Adam Palmer’s use of maleic hydrazide, with 50-60% control of volunteers in following crops also critical in the farm’s IPM strategy. His business, Fenland Farmers Ltd based in Ely, Cambridgeshire, grows 200-220ha of processing potatoes each year on organic soils around Ely, with most of its produce going into bags for the chip shop trade. Everything is harvested in October, graded into boxes and stacked in several stores, all of which have been upgraded in recent years to comply with CIPC stewardship requirements. As a result, most have good air ow, auto control and refrigeration, allowing them to be kept at a constant temperature, but because processing crops need to be stored at 8-10C, all four varieties Adam grows can have sprouting issues. Historically, Adam has spent £5-£6/t using CIPC, but this year they switched to mint oil as a direct replacement and total costs increased to £20/t, as four to ve applications have been used. Cheaper alternatives such as ethylene cannot be used by us as they have a detrimental e ect on fry colours. He says DMN would be a good alternative and is more competitively priced, but approval for 2021 looks unlikely. at’s why he believes maleic hydrazide is now essential in sprout control programmes. “It will vary between varieties and years, but realistically you can expect MH to give good control until January. “Nobody [except the grower] will absorb the extra cost of mint oil, so we have to nd a way to delay the need for other treatments and negate that expense. We are now reliant on MH to do that.” Volunteer control e farm has been an advocate for a number of years, with on-farm trials showing 50-60% reduction of volunteers in following cereal crops. In an area of intense potato production, this helps manage PCN, virus and soil-borne diseases, which are all perpetuated by volunteers. Adam has gained experience in how best to apply MH over a period of time and stresses the importance of crop condition at application. He says the crop should be growing well and free from stress, particularly heat stress. Tuber residue testing this year has shown better distribution of MH where the crop was more vigorously growing. Users may also want to consider tuber size at application more carefully and avoid spraying where there are signi cant numbers below 25mm. “We have seen that although they keep growing, absorption is always lower and that can cause issues in store. Fortunately, we don’t often see that, as our maincrop varieties tend to be treated in late August.” Another key factor is how the maleic hydrazide application dovetails with blight programmes. Adam stresses that it should be applied as a standalone application and protectant fungicides such as mancozeb avoided for at least four days either side of spraying. “We’ve certainly noticed that it can prevent uptake, but it won’t be available after this year so won’t always be a major concern.” Weather critical He points out that weather plays a more important role and aiming for no rain or irrigation for 24-48 hours after application is advisable to allow the product to be absorbed through the leaf. is means sprayer output is king when MH timing comes around and switching to liquid formulation Crown MH sped up sprayer lling times last year. “ e granular formulation works ne, but when you get it in the sprayer it froths up and we’ve tried most things, including anti- foaming agents, but can’t stop it completely. “We’ve found that Crown MH doesn’t foam as badly, and it has also been much easier to handle.” Adam will be ordering Crown MH again for 2021 in 600-litre IBCs with delivery into the sprayer via a retro t connector compatible with the Fastran 850 closed transfer system. e system is known to speed up lling, reduces operator exposure risk and cuts packaging waste, with a specialist contractor collecting empty IBCs free of charge for recycling. Farm Facts • Farming 1,600ha of predominantly black fen soils (50% owned, 50% contracted) • Grows 200-220ha of potatoes for chip shop trade • Varieties include Markies, Agria, Maris Piper and Sagitta • Refrigerated box storage houses crop until following summer “Nobody [except the grower] will absorb the extra cost of mint oil, so we have to find a way to delay the need for other treatments and negate that expense.” Adam Palmer, grower Crown MH IBCs can be returned free of charge for recycling.jpg