Sugar Beet Pestwatch

Dow AgroSciences UK regularly undertake sampling and monitoring of Leatherjacket populations throughout England and Scotland. The studies are carried out in conjunction with ADAS in England and SAC in Scotland. Pestwatch bulletins are prepared from the results and normally issued in March to alert sugar beet growers to the potential for damage from Leatherjackets to the newly-drilled crop.

The most recent Pestwatch Report:

LEATHERJACKETS 2008

The latest survey from autumn 2007 indicates a much lower risk of damage to susceptible crops in 2008 for England.  In Scotland the high levels of the last four years have also fallen to a little below levels seen in 2002, but 21% of sites were over the cereals damage threshold of 60 leatherjackets per square metre.

ENGLAND
A total of 46 sites were sampled in the three key regions shown below during autumn 2007.  The overall mean leatherjacket population was 15.7/m2 compared with a long term average of 67.6/m2.  The damage threshold for winter and spring cereals is 60/m2.

The Midlands/Western Region comprised Cheshire, Shropshire, Staffordshire, Warwickshire, and Herefordshire where a total of 25 sites were sampled.

The Northern Region covered North, South, and West Yorkshire where 27 sites were sampled.

The Southern Region had six sites sampled covering Berkshire, Hampshire and Oxfordshire.

Please note; it is not possible to sample every county, so the figures from sampling sites should be taken as a representative guide only.  Mean figures can conceal considerable variation, so low numbers are no guarantee that all sites will show similar levels.

The survey suggests there is a lower risk of damage to susceptible crops in all regions sampled.  In every case numbers are lower than the long term average.  The substantial reduction in numbers appears to be due to adverse weather in early-mid September. Waterlogging of soils in summer 2007 may also have been a contributory factor.

However, in spite of the low survey numbers, there have been some reports of leatherjacket damage in winter wheat and resown leys.
 
SCOTLAND

A total of 221 sites in west and central Scotland were sampled during November 2007 - January 2008.  Leatherjacket populations have fallen steeply from the extremely high levels of the past four years.  The overall mean leatherjacket population was 32/m2.  This compares with a 16 year mean of 101/m2. However, 21% of fields sampled had over 60/m2 and in these fields spring cereals will be at risk. Only in Dumfries/Kirkcudbright does the risk appear to be low.

Please note; it is not possible to sample every county, so the figures from sampling sites should be taken as a representative guide only.

Leatherjacket Damage Thresholds

ACTION

The risk of economic damage from leatherjackets this season is considerably lower than in recent years for susceptible crops in England and also in Scotland. However, the risk has not gone away. Fields with a history of leatherjacket damage, particularly going into spring cereals, should be monitored for large numbers of rooks and crows feeding on the larvae. Risk assessments and testing for the presence of leatherjacket larvae will provide a good indication of fields that are most likely to need treatment.  Because leatherjacket populations will vary from field to field, risks should be assessed before treatment is made. High infestations should be treated as soon as ground conditions permit.  Pre-ploughing treatments are more effective than those applied once damage is underway in the new crop.

If treatment is justified use Dursban* WG at 1.0 kg per hectare applied in 200 to 1000 litres of water. Control will be reduced if temperatures are below 5oC as the larvae will move deeper into the soil profile.

Always read the label. Use pesticides safely.          * Trademark of Dow AgroSciences LLC
Dursban WG contains chlorpyrifos

Learn more about Leatherjackets

Learn more about Dursban WG