Summer heatwaves take toll on potato harvest
With maincrop potato lifting well underway, Farmers Guardian catches up with two Hutchinsons agronomists to see how crops have fared after the hottest summer on record ...
Herefordshire - Jack Lane
Maincrop harvesting started towards the end of the first week in September in this region, and indications, at the time of writing, suggest some yields could be 20-25% down on last year due to the exceptionally dry summer.
Although crops generally went in really well and set good tuber numbers, those without irrigation struggled to bulk up given the lack of water, and even where irrigation was available, we are still seeing more small tubers than normal.
If harvester grade-outs are greater, volunteer risk in following crops could be increased and will need managing. The use of maleic hydrazide earlier in the season, post-harvest cultivations, and winter frosts, should all help to mitigate the risks, but any surviving volunteers next spring will need to be taken out to avoid increasing blight pressure in neighbouring potato crops.
Dry matter contents have also been quite high this season, therefore extra care is needed to minimise bruising during lifting and when loading crops into store. Rain after crop senescence and desiccation may reduce tuber DM content slightly, while moist soils should also help to alleviate some of the bruising risk during harvest operations.
One upside of the very dry summer was the relatively low blight pressure, which allowed a few cost savings on fungicide programmes. Some growers did invest more in foliar nutrition and biostimulants instead, to help support crops struggling to take up sufficient nutrients in dry soils. This has worked really well, resulting in healthier canopies and reducing stress. It appears to have helped reduce alternaria incidence too, as this was a notable issue in some drought-stressed crops.
This season has once again highlighted the importance of building the resilience of soils to extremes of wet and dry weather – both of which we have experienced in the past two seasons. This takes time and must be done across the rotation, considering cropping choices, cover crops, cultivation policy, and any other steps to build soil health and structure.
Yorkshire - Liam Hayton
As elsewhere, there is a lot of variation in yields, largely dependent on water availability. Early lifted crops of Lady Rosetta have generally yielded well where irrigation was available, but many other growers may well be expecting to be below contract, especially where water availability was limited.
It is interesting to see some varieties, such as Brooke, Royal and Markies, have coped better with the stress conditions than others that senesced more quickly, allowing early lifting and prompt establishment of a following cereal. Such variety characteristics may be something to look at more closely as part of a risk management strategy if such weather extremes are becoming more frequent.
Where crops retained green canopy well into September, some growers have held off harvest to allow them to bulk up. Remember though, that desiccant products may not be as effective applied later in the season, when UV levels are declining, putting more reliance on topping to help clear the canopy, before applying a desiccant to exposed stems. Blight programmes should also be maintained during this period.
Quality so far generally seems to be good, aside from the higher dry matters and smaller tubers already mentioned. The main issue for crops going into store is likely to be sprouting risk, which could well be greater in certain varieties due to the stress caused by hot, dry weather, and rapid accumulation of day degrees. It also remains to be seen how effective maleic hydrazide applications have been if conditions were dry at the time of application.
Looking ahead to next season, now is the time to start soil sampling for nutrients and potato cyst nematode on land going into potatoes in the spring. The sooner this is done, the sooner cropping, variety, and fertiliser decisions can be finalised.
It is worth noting that petiole sampling this season has shown more cases of phosphorus and nitrogen deficiencies in crops, largely due to roots struggling to take up nutrients from very dry soils. This has been a useful tool to help make sure the required foliar nutrition has been applied to help support crops through a challenging growing season.
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