Patience will be a virtue after wet winter – Arable Farming
Hutchinsons' root crop technical manager Darryl Shailes talks through all-things potatoes as one season draws near and the next cycle begins ...
Potato yields have been strong this season, and most stores were filled with good sized potatoes. However, we also saw that the earlier planted crops into wet, cold soils were much poorer, both in terms of yield and quality, than those planted even into June in drier, warmer conditions.
The work done by AHDB and the Cambridge University Potato Growers Research Association showed that smearing and compacting potato beds and ridges was a sure-fire way of reducing yield, so, patience will be a virtue come planting time.
I have not heard of any major breakdowns in-store being attributed to blight, which is good considering the level of blight in crops in 2023.
More worrying, is the development of blight-resistant strains in Europe. This appears to be driven by certain countries unwilling to give up on their blocking approach to fungicide usage.
In the UK, it has long been advised to alternate actives, not only to utilise a strong anti-resistance package, but also to manage minimum intervals between repeat application of some products.
Some EU countries have a different strategy and use two, three or even four applications of the same product as a stand-alone and this appears to have driven resistance development on some clones of blight to certain actives.
Towards the end of the blight control programme, repeat applications of fluazinam selected for the EU37 strain were subsequently found to be resistant to the active and several stores broke down with blight.
In reality
At first it was thought it was one single variety, but in reality it was not following a good anti-resistance programme that was at fault. This was later confirmed by the Eurofins trials the following summer, when the fluazinam-treated plots were destroyed by blight.
Unfortunately, the CAA group of chemistry, and now oxathiapiprolin, have also had clones of blight which have developed resistance by growers using repeat applications and not adopting a strong anti-resistant strategy. Some clones of EU43 have shown to be resistant to CAAs and some EU43 and EU46to oxathiapiprolin.
These resistant clones have developed rapidly in the Low Countries where repeat applications of the same active has been applied.
As it stands, EU43 and EU46 have not been detected in the UK, but we must be on our guard.
With the withdrawal of mancozeb in the UK going forward, which has been a very good component of a strong anti-resistance strategy, we will be more challenged.
At present, we have known resistance to Metalaxyl withEU13 and fluazinam to EU37 in the UK, with EU43 to CAA and both EU43 and EU46 to oxathiapiprolin in Europe.
We have a limited range of actives available and resistance to four of them is known. All of these actives will still need to be used, but in a different manner.
We often speak about integrated pest management and anti-resistance fungicide strategies, but they can no longer just be offered lip-service and must be at the forefront of any blight programme going forward.
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