AHDB Pest Bulletin weekly reports 2021

Welcome to the AHDB Pest bulletin weekly report. This useful forecast and pest report can help you inform your pest control programme.

If you have not done so already, subscribe to our weekly Pest Bulletin email alerts.

Read the latest report below for more information about current pest threats.

The AHDB Pest Bulletin can be found on the Syngenta UK web site

Carrot root flies emerging, cabbage root flies laying eggs, swede midge catches up

Key points:

Pest flies

  • Emergence of the second generation of carrot fly will be underway in all but the coldest locations; fly numbers are increasing at Wellesbourne
  • Egg laying by second generation cabbage root flies will be underway in all but the coldest locations; egg numbers have increased at Wellesbourne
  • Relatively low numbers of bean seed fly have been captured recently
  • AHDB are supporting a network of pheromone traps to monitor swede midge. The numbers of swede midges captured have increased considerably at some of the sites

Pest aphids and whiteflies

Pest beetles

Pest caterpillars

  • Citizen science observations show that diamondback moths are still being seen in the UK and on the continent, but not in very high numbers. Silver Y moths have been very abundant in Belgium and the Netherlands. There is evidence of a recent influx of silver Y moths into parts of the UK.  It is worth continuing to watch the web pages and your crops
  • Information on captures of diamondback moth by a national network of pheromone traps is reported on this webpage
  • Turnip moth caterpillars (cutworms) may be in crops and the cutworm forecast is underway in the Pest Bulletin. The risk of new egg-laying is decreasing
  • Small white butterflies are increasingly abundant

The AHDB Pest Bulletin can be found on the Syngenta UK web site

2nd generation carrot root flies now emerging and cabbage root flies laying eggs

Key points:

Pest flies

  • Emergence of the second generation of carrot fly will be underway at the warmest locations; fly numbers are increasing at Wellesbourne
  • Egg laying by second generation cabbage root flies will be underway in the warmest locations; egg numbers have increased at Wellesbourne
  • Relatively low numbers of bean seed fly have been captured recently
  • AHDB are supporting a network of pheromone traps to monitor swede midge. The numbers of swede midges captured have increased at some of the sites

Pest aphids and whiteflies

Pest beetles

  • Brassica flea beetles are still present at Wellesbourne. Rosemary Collier will be talking about a recent SCEPTREplus trial on flea beetle control in a webinar on 29 July
  • The new generation of adult pollen beetles will be emerging from oil seed rape crops

Pest caterpillars

  • Citizen science observations show that diamondback moths are still being seen on the continent. Silver Y moths have been very abundant in Belgium and the Netherlands. It is worth continuing to watch the web pages and your crops
  • Information on captures of diamondback moth by a national network of pheromone traps is reported on this web page, few have been captured recently apart from a recent influx at one site in Cornwall 
  • Turnip moth caterpillars (cutworms) may be in crops and the cutworm forecast is underway in the Pest Bulletin
  • Small white butterflies are increasingly abundant

The AHDB Pest Bulletin can be found on the Syngenta UK web site AHDB Pest Bulletin | Syngenta.  

Second generation carrot fly predicted for next week

Key points:

Pest flies

  • Emergence of the second generation of carrot fly is likely to start in just over a week’s time at the warmest sites
  • Egg laying by second cabbage root flies will be underway in the warmest locations
  • Bean seed flies are still active
  • AHDB are supporting a network of pheromone traps to monitor swede midge. A few swede midges have been captured in the past week

Pest aphids

  • 165 (217) willow-carrot aphids, 124 (96) black bean aphids, 29 (22) cabbage aphids, 45 (72) peach-potato aphids, and 38 (46) potato aphids were captured in the suction trap network during the week ending 4 July. Previous week’s totals in brackets
  • Information on the pest aphids of outdoor vegetable and salad crops captured in the AHDB network of yellow water traps in potato crops is summarised here. Aphid counts generally reflect those from the suction trap samples
  • As above, large numbers of willow-carrot aphids have been migrating, but numbers are continuing to decrease. Trials on the timing of virus transmission in carrot crops are continuing at Wellesbourne and in Yorkshire (FV 460 Investigating the timing of transmission of carrot viruses to improve management strategies | AHDB). Numbers of aphids on this year’s carrots at Wellesbourne have again decreased since the previous week 
  • The migration of lettuce root aphids from poplar to lettuce crops will be continuing

Pest beetles

  • Brassica flea beetles are still present at Wellesbourne
  • The new generation of adult pollen beetles is predicted to emerge from oil seed rape crops from early July onwards

Pest caterpillars

  • Citizen science observations show that diamondback moths are still being seen on the continent. Silver Y moths are quite abundant too. There have been some influxes of silver Y moth into the UK. It is worth continuing to watch the web pages and your crops
  • Information on captures of diamondback moth by a national network of pheromone traps is reported on this web page, relatively low numbers are being captured
  • Turnip moths are on the wing, caterpillars may be in crops and the cutworm forecast is underway in the Pest Bulletin

The latest edition of the AHDB Pest Bulletin was published on 8 July on the Syngenta UK web site: AHDB Pest Bulletin | Syngenta

The second generation of several pests is imminent

Key points:

Pest flies

  • Egg laying by first generation carrot flies will be low – numbers on traps at Wellesbourne are very low. Emergence of the second generation is likely to start from the third week of July at the warmest sites
  • Egg laying by second generation cabbage root flies is predicted to start in early to mid-July in the warmest locations. Numbers of flies captured in traps are increasing at Wellesbourne
  • Bean seed flies are still active
  • AHDB are supporting a network of pheromone traps to monitor swede midge. A few swede midges have been captured in the past week

Pest aphids

  • 217 (709) willow-carrot aphids, 96 (54) black bean aphids, 22 (29) cabbage aphids, 72 (251) peach-potato aphids, and 46 (133) potato aphids were captured in the suction trap network during the week ending 27th June. Previous week’s totals in brackets.
  • Information on the pest aphids of outdoor vegetable and salad crops captured in the AHDB network of yellow water traps in potato crops is summarised here. Aphid counts generally reflect those from the suction trap samples
  • As above, large numbers of willow-carrot aphids have been migrating, although numbers are continuing to decrease. Trials on the timing of virus transmission in carrot crops are continuing at Wellesbourne and in Yorkshire (FV 460 Investigating the timing of transmission of carrot viruses to improve management strategies).  Numbers of aphids on this year’s carrots at Wellesbourne have decreased since last week
  • The migration of lettuce root aphids from poplar to lettuce crops will be continuing

Pest beetles

  • Brassica flea beetles are still present at Wellesbourne but in low numbers
  • The new generation of adult pollen beetles is predicted to emerge from oil seed rape crops from early July onwards, numbers have increased in traps at Wellesbourne

Pest caterpillars

  • Citizen science observations show that diamondback moths are still being seen in northern Europe including the UK. Silver Y moths are quite abundant in northern Europe. It is worth continuing to watch the web pages and your crops
  • Information on captures of diamondback moth by a national network of pheromone traps is reported on this web page, relatively low numbers are being captured
  • Turnip moths are on the wing, caterpillars may be in crops and the cutworm forecast is underway in the Pest Bulletin

The latest edition of the AHDB Pest Bulletin was published on 1 July on the Syngenta UK web site: AHDB Pest Bulletin | Syngenta

Diamondback and Silver Y moths captured in Dorset and seen in SW

Key points:

Pest flies

  • Egg laying by first generation carrot flies will be continuing to decrease – numbers on traps at Wellesbourne are very low. Emergence of the second generation is likely to start from the third week of July at the warmest sites
  • Egg laying by second cabbage root flies is predicted to start in early-mid July in the warmest locations
  • Bean seed flies are still active
  • AHDB are supporting a network of pheromone traps to monitor swede midge. Very few swede midge have been captured in the past week

Pest aphids

Pest beetles

  • Brassica flea beetles are still present at Wellesbourne but in low numbers
  • The new generation of adult pollen beetles is predicted to emerge from oil seed rape crops from early July onwards

Pest caterpillars

  • Citizen science observations show that diamondback moths are being seen in northern Europe and in the UK, large numbers were captured on Portland Bill on the nights of 28 and 29 June. Silver Y moths are still quite abundant in northern Europe and again large numbers were captured on Portland Bill on the night of 28 June and seen on the Lizard Cornwall on 28 June (personal observation). This is the time of year when influxes do occur and it is worth watching the web pages and your crops
  • Information on captures of diamondback moth by a national network of pheromone traps is reported on this webpage, relatively low numbers are being captured
  • Turnip moths are on the wing, caterpillars may be in crops and the cutworm forecast is underway in the Pest Bulletin

The latest edition of the AHDB Pest Bulletin was published on 24 June on the Syngenta UK web site AHDB Pest Bulletin | Syngenta

Numbers of several species of aphid are steadily increasing. 

Key points:

Pest flies

  • Egg laying by first generation carrot flies will be continuing to decrease – numbers on traps at Wellesbourne are very low
  • Egg laying by first generation cabbage root flies will be continuing to decrease in warmer areas – egg and fly numbers at Wellesbourne are very low. The second generation is predicted to start in mid-July in the warmest locations
  • Bean seed flies are still active
  • AHDB are supporting a network of pheromone traps to monitor swede midge. Small numbers of swede midge have been captured in the past week

Pest aphids

Pest beetles

Pest caterpillars

  • Citizen science observations show that diamondback moth numbers were at their highest so far this year around 18-19 June in Belgium and the Netherlands Diamondback moth sightings 2021 (warwick.ac.uk). Large numbers were observed in Kent around 16  Silver Y moths are still quite abundant in Belgium and the Netherlands Silver Y moth sightings 2021 (warwick.ac.uk). This is the time of year when influxes do occur and it is worth watching the web pages and your crops
  • Information on captures of diamondback moth by a national network of pheromone traps is reported on this web page, small numbers are being captured Monitoring diamond-back moth in commercial crops 2021 (warwick.ac.uk)
  • Turnip moths are on the wing, caterpillars may be in crops and the cutworm forecast is underway in the Pest Bulletin

The latest edition of the AHDB Pest Bulletin was published on 17 June on the Syngenta UK web site AHDB Pest Bulletin | Syngenta

Most aphid species increasing rapidly. Carrot crops are under particular pressure. 

Key points:

Pest flies

  • Egg laying by first generation carrot flies will be decreasing
  • Egg laying by first generation cabbage root flies will be decreasing in warmer areas
  • Bean seed flies are still active
  • AHDB are supporting a network of pheromone traps to monitor swede midge. Small numbers of swede midge have been captured in the past week

Pest aphids

Pest beetles

Pest caterpillars

The latest edition of the AHDB Pest Bulletin was published on 10 June on the Syngenta UK web site AHDB Pest Bulletin | Syngenta. Carrot crops are under particular pressure from aphids at the moment. Key points:

Pest flies

  • Egg laying by first generation carrot flies will be starting to decrease
  • Egg laying by first generation cabbage root flies will be starting to decrease in warmer areas
  • Bean seed flies are still active
  • AHDB are supporting a network of pheromone traps to monitor swede midge. Small numbers of swede midge have been captured in the past week

Pest aphids

Pest beetles

Pest caterpillars

The latest edition of the AHDB Pest Bulletin was published on 3 June on the Syngenta UK web site AHDB Pest Bulletin | Syngenta. A number of pests have become more abundant. Key points:

Pest flies

  • Egg laying by first generation carrot flies will be continuing
  • Egg laying by first generation cabbage root flies will be continuing
  • Bean seed flies are still active
  • AHDB are supporting a network of pheromone traps to monitor swede midge. No swede midges have been captured in the past week

Pest aphids

Pest beetles

  • Numbers of pest beetles captured at Wellesbourne have increased over the last week, probably in response to the better weather conditions AHDB Horticulture Pest Blog - including crop viruses, University of Warwick. Numbers of brassica flea beetles are particularly high and the beetles are causing damage to susceptible crops including a SCEPTREplus trial on control of brassica flea beetles, which is underway at Wellesbourne

Pest caterpillars

  • There have been no significant influxes of diamondback moths into the UK since around 9 May Diamondback moth sightings 2021 (warwick.ac.uk). Silver Y moths have been quite abundant in Belgium and the Netherlands recently and may have ‘spilled over’ into eastern England Silver Y moth sightings 2021 (warwick.ac.uk). This is the time of year when influxes do occur and, for example, conditions were suitable for migrants to arrive on the night of 2 June. It is worth watching the web pages and your crops
  • Information on captures of diamondback moth by a national network of pheromone traps is reported on this web page Monitoring diamond-back moth in commercial crops 2021 (warwick.ac.uk)
  • More turnip moths (cutworms) have been captured at Wellesbourne. The cutworm forecast indicates that eggs are likely to take about 2 weeks to hatch

The latest edition of the AHDB Pest Bulletin was published on 27 May on AHDB Pest Bulletin | Syngenta.  The forecast improvement in the weather is likely to increase the activity of some pests. Key points:

Pest flies

  • Egg laying by first generation carrot flies will be continuing
  • Egg laying by first generation cabbage root flies will be continuing
  • Bean seed flies are still active
  • AHDB are supporting a network of pheromone traps to monitor swede midge. No swede midges have been captured in the past week

Pest aphids

Pest beetles

Pest caterpillars

The latest edition of the AHDB Pest Bulletin was published on 20 May on the Syngenta UK web site AHDB Pest Bulletin | Syngenta. The effect of the cold spring on the activity of certain pests is still apparent. Key points:

Pest flies

  • Egg laying by first generation carrot flies will be continuing at all but the coldest sites
  • Egg laying by first generation cabbage root flies will be continuing at all but the coldest sites
  • Bean seed flies are still active
  • AHDB are supporting a network of pheromone traps to monitor swede midge. One swede midge has been captured in the past week

Pest aphids

  • Two willow-carrot aphids, 1 black bean aphid, 3 peach-potato aphids and 1 potato aphid were captured in the suction trap network during the week ending 9 May Aphid Bulletin Archive - aphids | Insect Survey
  • Information on the pest aphids of outdoor vegetable and salad crops captured in the AHDB network of yellow water traps in potato crops is summarised here https://warwick.ac.uk/fac/sci/lifesci/wcc/research/pests/aphids/2021/. Small numbers of peach-potato aphid, potato aphid, black bean aphid and willow-carrot aphid were captured during the week ending 20 May.  These were from traps towards the south of the country (South-West, Midlands, East Anglia)
  • Willow-carrot aphids are likely to be starting their migration from willow to carrot and other ‘summer’ hosts. This has been delayed compared with last yearWe are unsure at the moment how much contribution the aphids that overwinter on carrots Monitoring aphids on carrot at Wellesbourne (warwick.ac.uk), as opposed to willow, make to transmission of virus in carrot 
  • Trials on the timing of virus transmission in carrot crops have begun at Wellesbourne and in Yorkshire (FV 460 Investigating the timing of transmission of carrot viruses to improve management strategies | AHDB). During the week ending 18 May, average numbers of willow-carrot aphids captured in yellow water traps in the trial plots were 1 in Yorkshire and 6 at Wellesbourne
  • The forecast for black bean aphid indicates that flight activity will be later than in 2020

Pest beetles

Pest caterpillars

The latest edition of the AHDB Pest Bulletin was published on 13 May on the Syngenta UK website. The cold weather has delayed the activity of some pests.

Key points:

Pest flies

  • Egg laying by first generation carrot flies will be underway at all but the coolest sites
  • Egg laying by first generation cabbage root flies will be underway at all but the coolest sites
  • Counts of bean seed fly from Warwickshire, Yorkshire and Lincolnshire are available in the Pest Bulletin
  • AHDB are supporting a network of pheromone traps to monitor swede midge. Traps are already running at a few sites. One swede midge has been captured in the past week

Pest aphids

  • One willow-carrot aphid, 1 black bean aphid, 1 peach-potato aphid and 5 potato aphids were captured in the suction trap network in the week ending 2 May Aphid Bulletin Archive - aphids | Insect Survey
  • Information on the pest aphids of outdoor vegetable and salad crops captured in the AHDB network of yellow water traps in potato crops will be summarised here https://warwick.ac.uk/fac/sci/lifesci/wcc/research/pests/aphids/2021/
  • Willow-carrot aphids are likely to be starting their migration from willow to carrot and other ‘summer’ hosts; this has been delayed compared with last year
  • The wingless willow-carrot aphids that have been overwintering on carrots at Wellesbourne have continued to increase in number and a few more winged aphids are present this week Monitoring aphids on carrot at Wellesbourne (warwick.ac.uk)  
  • We are unsure at the moment how much contribution the aphids that overwinter on carrots, as opposed to willow, make to transmission of virus in carrot
  • The first forecast for black bean aphid has been produced and indicates that flight activity will be later than in 2020

Pest beetles

Pest caterpillars

The latest edition of the AHDB Pest Bulletin was published on 6 May on the Syngenta UK website. The cold weather appears to be slightly delaying the activity of some pests.

Pest flies

  • Egg laying by first generation carrot flies is likely to start from the weekend onwards, being slightly later at cooler sites
  • Carrot flies will be continuing to emerge from the soil, and over 1,000 carrot flies have been captured at Wellesbourne during the past week 
  • Egg laying by first generation cabbage root flies will be underway at all but the coldest sites, but appears to have been slightly delayed by the cold weather. Three eggs were found at Wellesbourne during the past week (on 15 plants)
  • We are testing a preliminary forecast for bean seed fly. This predicts that the first period of activity is underway at all but the coldest sites. However, the numbers trapped at Wellesbourne have been quite low, suggesting that they have been affected by the cold weather
  • AHDB are supporting a network of pheromone traps to monitor swede midge. Traps are already running at a couple of sites. No swede midges have been captured in the past week

Pest aphids

  • No aphids of relevance to vegetable crops were captured in the network of suction traps in the week ending 25 April
  • It is worth watching the day-degree forecast for willow-carrot aphid as we are getting closer to the start of the migration from willow to carrot and other ‘summer’ hosts, although again it has been delayed compared with last year
  • The wingless willow-carrot aphids that have been overwintering on carrots at Wellesbourne have continued to increase in number and winged aphids are present this week Monitoring aphids on carrot at Wellesbourne (warwick.ac.uk). We are unsure at the moment how much contribution the aphids that overwinter on carrots, as opposed to willow, make to transmission of virus in carrot
  • The first forecast for black bean aphid has been produced and indicates that flight activity will be later than in 2020

Pest beetles

Pest caterpillars

The latest edition of the AHDB Pest Bulletin was published on 29 April on the Syngenta UK web site AHDB Pest Bulletin | Syngenta. Several important pests are becoming active. Key points:

Pest flies

  • Egg laying by first generation carrot flies is likely to start next week at all but the coldest sites. Carrot flies will now be emerging from the soil and more than 40 have been captured at Wellesbourne during the last week 
  • By early next week, egg laying by first generation cabbage root flies will be underway at all but the coldest sites. Two eggs were found at Wellesbourne on 27 April
  • We are testing a preliminary forecast for bean seed fly. This predicts that the first period of activity is underway at all but the coldest sites
  • AHDB are supporting a network of pheromone traps to monitor swede midge. Traps are already running at a couple of sites.  A single midge has been captured so far

Pest aphids

  • One peach-potato aphid was captured at Silwood Park in the week ending 12 April and one potato aphid at Writtle
  • It is worth watching the day-degree forecast for willow-carrot aphid as we are getting closer to the start of the migration from willow to carrot and other ‘summer’ hosts. The wingless willow-carrot aphids that have been overwintering on carrots at Wellesbourne have continued to increase in number and winged aphids are present this week Monitoring aphids on carrot at Wellesbourne (warwick.ac.uk). We are unsure at the moment how much contribution the aphids that overwinter on carrots, as opposed to willow, make to transmission of virus in carrot

Pest beetles

Pest caterpillars

The latest edition of the AHDB Pest Bulletin was published on 22 April on AHDB Pest Bulletin | Syngenta.  Whilst there is still relatively little pest activity to report so far, insects will be on the move soon. Key points:

Pest flies

  • Egg laying by first generation carrot flies is forecast to start in early May at the warmest sites. They will be starting to emerge from the soil now. No carrot flies have been captured at Wellesbourne so far
  • Egg laying by first generation cabbage root flies will be underway in Cornwall and starting towards the end of April in most other areas. A small number of cabbage root flies have been captured at Wellesbourne AHDB Horticulture Pest Blog - including crop viruses, University of Warwick. No eggs have been found at Wellesbourne so far
  • We are testing a preliminary forecast for bean seed fly. This predicts that the first period of activity has started in some areas
  • AHDB are supporting a network of pheromone traps to monitor swede midge. Traps are already running at a couple of sites but no midges have been captured so far

Pest aphids

  • The Rothamsted Insect Survey’s long range forecasts for cereal aphids, together with peach-potato aphid, potato aphid and cabbage aphid, have been published When will aphids fly this year? (aphid forecasts) | AHDB. In the absence of abnormal conditions this spring, such aphids are forecast to fly around 2–3 weeks later in Scotland and Northern England. Over much of the rest of England, aphids will fly around average to one week later than average. One peach-potato aphid was captured at Hereford in the week ending 5 April
  • It is worth watching the day-degree forecast for willow-carrot aphid. Willow-carrot aphids that have been overwintering on carrots at Wellesbourne have survived the cold period and are increasing in numbers Monitoring aphids on carrot at Wellesbourne (warwick.ac.uk). We are unsure at the moment how much contribution the aphids that overwinter on carrots, as opposed to willow, make to transmission of virus in carrot

Pest beetles

Pest caterpillars

 

The latest edition of the AHDB Pest Bulletin was published on 15 April on AHDB Pest Bulletin | Syngenta. Whilst there is relatively little pest activity to report so far, insects will be on the move when the weather warms up. Key points to note:

Pest flies

  • Egg laying by first generation carrot flies is forecast to start in early May at the warmest sites. No carrot flies have been captured at Wellesbourne so far 
  • Egg laying by first generation cabbage root flies was forecast to start this week in Cornwall, but towards the end of April in most other areas. A very small number of cabbage root flies have been captured at Wellesbourne AHDB Horticulture Pest Blog - including crop viruses, University of Warwick
  • We are testing a preliminary forecast for bean seed fly. This predicts the first period of activity in the spring and the forecast suggests this is imminent in some areas

Pest aphids

  • The Rothamsted Insect Survey’s long range forecasts for cereal aphids, together with peach-potato aphid, potato aphid and cabbage aphid, have been published When will aphids fly this year? (aphid forecasts) | AHDB. In the absence of abnormal conditions this spring, such aphids are forecast to fly around 2–3 weeks later in Scotland and Northern England. Over much of the rest of England, aphids will fly around average to one week later than average
  • Willow-carrot aphids that have been overwintering on carrots at Wellesbourne have survived the cold period and are now increasing in numbers Monitoring aphids on carrot at Wellesbourne (warwick.ac.uk). We are unsure at the moment how much contribution the aphids that overwinter on carrots, as opposed to willow, make to transmission of virus in carrot

Pest beetles

Pest caterpillars

The first AHDB Pest Bulletin of 2021 was published last Thursday on AHDB Pest Bulletin | Syngenta

There is relatively little activity to report so far, although insects will be on the move when the weather warms up. Key points to note: 

Pest Aphids

  • The Rothamsted Insect Survey’s long range forecasts for cereal aphids, together with peach-potato aphid, potato aphid and cabbage aphid, have been published When will aphids fly this year? (aphid forecasts) | AHDB. In the absence of abnormal conditions this spring, such aphids are forecast to fly around 2–3 weeks later in Scotland and Northern England. Over much of the rest of England, aphids will fly around average to one week later than average 

Pest Flies

  • No carrot flies have been captured so far at Wellesbourne. At present, egg-laying is forecast to start in early May at the warmest sites 

Caterpillars

  • No caterpillars have been recorded yet this season

Pest Beetles

Resources

  • Listen to the Pest Bulletin podcast which is due out on 19 April

Have a question? Ask the team ...

Dawn Teverson

Knowledge Exchange Manager - Field Vegetables (Alliums, Brassicas, Carrots, Legumes)
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