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Delay in drilling and cold weather means it is probable we will have to treat beet for aphids – Arable Farming – Darryl Shailes

The old saying goes 'March winds and April showers bring forth May flowers' ...

Not this season, however, which has seen the coldest and driest April since records began. May has brought much needed showers-and how things have changed since the rain, with the countryside changing from a yellow and purple hue to green with flowers and blossom. Although I think the lack of frost has had more of an impact than the rain.

The cold weather has delayed our asparagus, the swallows have only just arrived and I’ve yet to hear a cuckoo in the valley. Last year I heard one on April 11 and those big black bibionids, commonly known as St Mark’s flies as they normally emerge on St Mark’s day on April 24, are only now appearing around two-three weeks late. Will all the old names and sayings have to be changed with the changing climate?

I don’t think I’ve got a crop of beet that will be down the row by Suffolk Show, although they have grown a lot in the last few days. With this recent rapid growth, we can anticipate some crop damage from herbicides as sugar beet is the most susceptible to damage at the 2-3 leaf stage with rapid growth and warmth. Historically it’s always the same, although even with the best planning we sometimes get caught out.

I have just seen my first Cavariella aegopodii (carrot willow aphid) and Myzus persicae (peach potato aphid), again a month later than last year, although last year they were very early.

On guard

Over the next few weeks, we will have to be on our guard to ensure the virus they can carry won’t affect crops. Virus yellows in sugar beet was a huge issue in 2020 and when the emergency approval for Cruiser SB (thiamethoxam) wasn’t forthcoming, as the cold weather in January and February meant that the criteria in the approval weren’t met, we assumed it wouldn’t be an issue as the beet would be too far forward to be badly affected.

However, the delay in drilling and then the cold weather means it’s now probable we will have to treat the beet once or even twice to get them to the 12-14 leaf stage when virus transmission is likely to be less. We’ll be down on our hands and knees checking for the green wingless aphid threshold of one per four plants until the 12-14 leaf stage-so an aching back for the next three-four weeks or so. Old age is a wonderful thing.

We’ve just had a new emergency approval come through, so at least we’ll have a chance of managing if we get the timing correct.

Carrot willow and peach potato aphids can both transmit virus in potatoes, so monitoring of yellow water and sticky traps also becomes a priority over the next few weeks in seed crops. We have an armoury, even though it’s quite limited, especially against virus yellows which as we know is a non-persistent virus, so managing transmission with insecticides is a real challenge.

Virus management in potatoes is now at the forefront of integrated pest management and cover crops, location, use of resistant varieties, barrier crops and barrier sprays are now as important as insecticides.

The integrated crop management aspects of our industry are increasing rapidly, driven by sustainability, justification, cost and the approval arena we work in. It will be interesting to see what it leads to over the next few seasons.

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