Learning lessons from a mixed season – Farmers Guardian – Tom Rowe
In the last in its series, Farmers Guardian talks to two agronomists to review the 2021 potato season and discuss what lessons can be taken into next year ...
South West: Tom Rowe, Hutchinsons, Devon/Cornwall border
With green-top crops harvested back in July/August, and maincrop harvesting progressing, yields and quality generally seem okay despite such a mixed season weather-wise.
Keeping on top of disease has been the biggest challenge, with blight warnings triggered most weeks. This required the use of stronger chemistry throughout much of the season, which has performed well, providing spray timings were kept tight.
Many growers are getting good results from flailing crops before applying a carfentrazone-ethyl based desiccant, plus blight spray, a few days later. Although it is a slightly slower process than diquat, flailing seems more effective than desiccating with sprays alone, providing ground conditions allow you to travel.
Of course, much depends on the determinacy of the variety grown, and this year we have also seen how much difference the weather around application timing can make.
Desiccants have worked noticeably better where they were applied during hot, sunny spells, compared with those that went on in duller, cooler weather.
Control
We have also seen the impact of the cool, dry spring on residual weed control in crops that were slow to emerge. Where residuals ended up being applied too far in advance of crops emerging, a post-emergence tidy-up was required.
Generally, there was not a wide weed spectrum left to control, but given the limited post-ems available, it highlights the importance of maximising pre-em efficacy. Looking longer term, more growers are recognising the benefits of overwinter cover crops for improving soil ahead of potatoes. We have seen soil become more friable and workable, which facilitates earlier ground preparation and planting in the spring.
East: Jack Richardson, Farmacy, Lincolnshire
Crops grown from larger, chitted seed have generally looked much better throughout the season as they gained a valuable head start in the spring. Time will tell whether this results in a yield benefit too.
Chitting seed is an expensive process, but where there is an opportunity, it is a good insurance policy in cold seasons. A compromise might be to chit early-sown crops and leave those planted later unchitted as they are more likely to go into warmer soils. If chitting is not possible, then waiting for soils to warm up may be worthwhile for certain varieties and soil types.
There remain concerns about seed availability next season given the ongoing trade ban with Holland following failure to agree a post-Brexit deal. There is plenty of seed grown in the UK but imported varieties may be limited if no agreement can be reached, so it is worth securing supplies early.
The 2021 season has also highlighted the value of having good quality land free from potato cyst nematode (PCN). In slow growing conditions like those experienced earlier this year, PCN can hit crops hard, even those that have been treated. Identify problem areas and analyse soil accurately to formulate a management plan.
It is also worth noting the benefits trickle irrigation systems have afforded in a high blight pressure season. Trickle systems performed really well in maintaining adequate soil moisture levels while reducing blight pressure compared with overhead irrigation.
The blight chemistry available has generally done a fantastic job keeping crops clean, although we have seen how quickly pressure builds when intervals slip, even by just a couple of days.
Irrigated crops can be particularly challenging given the logistics of getting in to spray ahead of the irrigator.
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