Rapid summer growth helps potatoes make up lost time – Farmers Guardian
As maincrop potato lifting gets underway, the final article in our series on potatoes gets the views of two of Hutchinsons agronomists about this year's harvest and the lessons to...
NORTH WEST, ARCHIE BOASE, CHESHIRE
After something of a roller-coaster season, prospects for main crop yields and quality generally look reasonably good.
Crops put on tremendous growth over a warm, wet summer, quickly making up for a slow start in a wet, then dry, spring.
Rapid growth and bulking has triggered some secondary growth and tuber splitting though, which may affect marketable yield.
There are also some very large tubers, which could pose more of an issue for those supplying crisping markets.
Where heavier land has been very wet, a few incidents of scab have also been found on susceptible varieties such as Marfona, caused where the lenticels have enlarged and burst in anaerobic soils.
Large canopies have taken more effort to burn down this year, especially where flailing has not been used, or was not possible due to wet soils.
In some cases, crops needed four applications of carfentrazone or pyraflufen at seven-day intervals. This highlights the need to plan maleic hydrazide applications for sprout suppression carefully next year.
Ideally, at least five weeks is needed between application and the start of burn-off, which itself may take two to four weeks.
Additionally, we need to allow another three weeks or so for skin set, so maleic hydrazide really needs to go on as soon as flowering finishes, to avoid extra delays.
Tubers
Tubers have to be above 25mm before applying maleic hydrazide, but people often hold out too long waiting for everything to reach this size, which may not be best longer term.
The 2023 season has seen the highest blight pressure for several years, reinforcing the value of a good programme, robust chemistry and tight intervals.
Unsettled weather often made it difficult to apply fungicides, so having chemistry like oxathiapiprolin, where intervals can stretch to 10 days, or the kickback of cymoxanil, has helped massively.
Systemic products have been useful too, especially if blight got onto the leaf, as the last thing you want is for it to infect tubers.
As ever, once potatoes are lifted, it is vital to establish cover on bare ground over winter, to reduce the risk of erosion and nutrient leaching. First wheats often perform really well after potatoes, doing an excellent job of ‘mopping up’ nutrients and protecting soil structure.
SOUTH EAST, GEORGE BAXTER, CAMBRIDGESHIRE FENS
After a two-to-three-week delayed start to the season, many crops in this region have actually reached harvest a week or so earlier than normal, thanks to good growing conditions throughout the summer.
The spell of hot weather earlier in September also came at just the right time to help canopy desiccation, although topping and spraying has given better results than spraying alone on the more indeterminate varieties.
Yields look promising, despite slightly low tuber numbers in some cases, possibly a consequence of crops racing through canopy expansion and reaching flowering so quickly.
Some growth cracks and misshapen tubers have occurred too, but quality and skin finish are generally good.
This season’s high blight pressure has reinforced the value of adopting a robust spray programme that can be adjusted as the season plays out, using the most appropriate chemistry when and where it is needed, rather than being too prescriptive.
Blight
Intervals have been kept tight (weekly) throughout, and blight forecasts have been a useful tool to help monitor in-season risk and plan the most effective options.
Looking ahead to next year’s crop there is an ongoing shift away from ploughing ground destined for potatoes towards non-inversion, reduced tillage systems, often including overwinter cover crops.
This generally involves subsoiling in autumn, before planting with a specialist one-pass planter in spring. It may not suit all soil types, varieties, or end markets, but it does seem to be working really well on farms doing it in this area, especially those on lighter-bodied black fen soil.
Travelling on fields in spring is easier, and there have been improvements to moisture holding capacity, structure and soil stability over the winter, and in the ridges at planting.
From a soil health perspective, and potential cost savings from reduced passes, it is certainly something worth considering.
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