Navigating a frustrating start to potato planting – Farmers Guardian
Poor field conditions from wet weather has delayed potato planting across many regions. Farmers Guardian talks to two agronomists about tackling another challenging season. ...
Fife: Morven Anderson, Hutchinsons
There is building frustration about the lack of planting progress in Fife. However, avoid forcing crops into wet, cold soils. Doing so not only compromises soil health and rooting, but is likely to mean slower emergence, increasing the risk of rhizoctonia and little potato disorder, especially in more susceptible varieties.
Experience shows crops planted into good, warm seedbeds invariably overtake those forced into sub-optimal conditions earlier in the season, so it is usually worth holding out where possible. Planting later does inevitably reduce an already tight growing window, so we must ensure nothing inhibits establishment and crop development once seed is finally in the ground.
Particular care is needed with timing of pre-emergence contact herbicides to minimise risks to emerging crops. Many products allow application at up to 10 percent crop emergence, but in a season like this, it may be worth going earlier to avoid any potential checks to growth.
Adequate seedbed nutrition is essential, particularly for water-soluble nutrients such as nitrogen and sulphur, which are likely to have experienced higher water losses. N builds early yield potential, while sulphur is integral to nitrogen use efficiency.
Previous research in Scotland has found yield responses in potatoes from sulphate applications of up to T20kg/hectare, so check you are applying enough to get the best out of N. If conditions turn dry later in the season, a foliar N top-up may also be worthwhile to maintain the canopy health and longevity.
Phosphate and potash are equally important for establishment, and applications should be tailored to soil requirements and crop offtake.
Roughly, one tonne of tubers removes; 3kg/ha of phosphate and 5.8kg/ha of potash.
Later planting could potentially exacerbate potato cyst nematode or free-living nematode impacts, so where soil testing has identified higher levels, apply appropriate treatments of frosthiazate or fluopyram to help developing crops escape any initial feeding damage.
Once potatoes have emerged, experience shows foliar phosphite based biostimulants can give a valuable boost to rooting, so they may be a good option once there is sufficient leaf area to treat (typically from rosette stage onwards).
Looking ahead, it is worth noting that the UK and European supermarket stocks are generally tight, and will deplete further into the summer, so farmers may be encouraged to start lifting earlier this season.
This will potentially strain the 2024 harvest tonnage, although prices could rise if that happens.
East Midlands: Tom Hopkins, Farmacy
The East Midlands has been one of the worst affected regions, with some areas having recorded their entire annual rainfall in the past six months. Unsurprisingly, planting progress is well behind schedule, with very little in the ground by mid-April, except for a few earlies on lighter soils.
Growers are understandably eager to get going, but previous seasons show patience can be a virtue, especially when soils appear dry on the surface but remain wet at depth. Working wet soils too soon risks smearing and compaction, which impedes rooting and compromises the crop’s ability to access nutrition and water through the season.
Last year’s wet April is a good example, some pressed on with planting in sub-optimal conditions, while others waited for soils to improve, and in many cases those later-planted crops soon caught up and outperformed earlier plantings.
Fields should be assessed individually, so cultivations, planting and agronomy decisions can be tailored accordingly. Planting is likely to be staggered, so extra care and flexibility is needed to manage crops at different stages-with a range of planting dates, you cannot treat everything as one when it comes to other aspects, such as weed control.
Pre-em chemistry is key to early weed control, with actives such as metribuzin, prosulfocarb, adonithen and pendimethalin being the mail residual options, plus carfentrazone providing specific contact activity.
As ever, herbicide choice depends on target weed spectrum and any soil type or varietal restrictions. Glyphosate is also an option for controlling grass-weeds but must be used before crop emerge- make sure to check label restrictions as not all glyphosate products are approved.
If conditions are wet around planting but soils dry out in the following weeks, beware of ridges cracking and exposing the emerging crops, which could increase potential risks from contact chemistry.
Finally, take time to plan blight strategies if not done already. With ongoing concerns about new, more aggressive genotypes and fungicide resistance, a robust plan should be in place, utilising a range of actives and modes of action. Product choices can then be fine-tuned as the season progresses depending on the risks to individual crops.
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