A hard winter helps a huge amount when it comes to aphids – Arable Farming – Darryl Shailes
It has been a very strange winter for me. Normally I would spend some time on the ski slopes for a few weeks in January ...
Getting a bit fitter and enjoying some winter sun above the clouds in the valley
This one, however, has been a bit ‘dreich’, if my Scottish friends will pardon my use of the word.
It is not a word I have ever used before, but it sums up January in the Waveney Valley in 2021 – cold, wet and gloomy, and that’s not just the weather. A third lockdown has not helped.
Every time it has rained the garden has flooded again and I was running out of vitamin D tablets to ward off seasonal affective disorder. But then the Beast from the East Two hit us and with it came snow.
With the snow and sunshine, it is almost like being in the Alps. I have even managed to make some fresh tracks in the snow over the river in Suffolk, where some relatively steep, grassy meadows have enabled me to get the skis out.
I’ve skied powder in many valleys in Europe – the Otztal valley in Austria, where my daughter lives, the Chamonix valley in France and now the Waveney Valley. Who would have thought – although the lift system could do with upgrading.
This cold snap will also do our day job some good.
As we have discussed previously, the emergency approval for Cruiser SB (thiamethoxam) is subject to the Rothamsted virus prediction model being triggered. That may not happen now, but it is a good thing.
The model is designed to determine the risk of aphids and virus in sugar beet. Cold weather in January and February delays the onset of the aphids’ migration, so they should be much less damaging.
Challenging
In 2018, the Beast from the East had great effect and delayed the peak aphid migration until June when the crop is more able to tolerate the virus, not early April like it was last year.
The cold winter will also help the potato crop as the very early migration of aphids in seed production and generally warmer weather meant virus management in seed was very challenging in 2019.
Potato virus Y(PVY) is very difficult to manage with aphicides because it is transmitted in a non-persistent manner.
This means that if the aphids feed on a plant that has the virus, it can instantly transmit to another plant when it feeds.
To reduce PVY, grow seed in fields isolated from potential sources of virus and where aphids are absent or hopefully low in numbers.
Early generation primary seed clean of virus and the use of mineral oils, catch crops and mulches are all part of the strategy.
A good old-fashioned hard winter helps a huge amount, as the aphids that survive migrate much later and hopefully much of the seed production will be done before they have a chance to cause a problem.
Potato leaf roll virus is a bit different because it is a persistent virus which takes some time to transmit.
This is because the aphids need to feed for a while before they can infect the new plants so it is more manageable with the few aphicides we have left, but still the winter will be a benefit.
The cold weather will also help with soil management. Getting some good winter mould will help to produce good seedbeds for beet and deep, penetrating frosts help kill potato volunteers. All good news – and I get to ski.
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