|
|
|
 |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Cereal PestwatchDow AgroSciences UK regularly undertake sampling and monitoring for the most important insect pests of cereals in the UK. 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 weekly during the key periods of potential threat from the relevant pest.
To find out more about this service, please contact our Technical Hotline on 0800 689 8899 or E-mail. For the most recent Pestwatch Reports on Leatherjackets and Wheat Bulb Fly see below: WHEAT BULB FLY Following is egg hatch and plant invasion data for 20 February 2006. There has been a rapid increase in egg hatch and plant invasion at all sites.
Action: Use Risk Assessment Charts to identify fields at high risk. Applications of Dursban WG at 1.0 kg/ha in 200 to 1,000 litres per hectare of water should be made to fields in the highest risk category. If necessary, Dursban WG can be applied to frosty ground but should NOT be tank mixed. Dursban WG must NOT be applied in tank mix with Atlantis WG, regardless of weather conditions. An interval of 14 days must be observed between applications of Dursban WG and Atlantis WG. Atlantis is a trademark of Bayer CropScience Ltd Mean leatherjacket populations in England were high in comparison with recent years. In midlands and northern areas they were the highest recorded in the period 1991-2005. In southern areas they were the highest since 2001. The data indicate an overall high risk of damage to susceptible crops after grass. From the 47 sites surveyed in England during autumn 2005, 83% contained populations greater than 50/m2, i.e. exceeding the advisory threshold above which damage to following spring cereal crops and sugar beet is possible. (34% last year) A total of 165 fields were surveyed in west and central Scotland between November 2005 and January 2006. Leatherjacket numbers were found to be extremely high across most surveyed areas. The average population density of 250 grubs per square metre is the highest ever recorded in 30 years of sampling. There is a potentially very high risk of damage to spring cereals and root crops following grass. There is also a real threat to grass yields in three-quarters of the fields sampled. Leatherjacket populations in grassland this year are very high. The risk of damage is very high in most areas, especially Ayrshire, Bute, Dumfries/Kirkcudbright, Lanarkshire, Renfrew and Wigtownshire. Over 80% of fields sampled were infested with in excess of 0.6 million leatherjackets per hectare and 75% of fields sampled contained population densities above 1.0 million per hectare. Nearly 40% contained densities of more that 2.0 million per hectare. The population threshold for treating permanent pasture is one million leatherjackets per hectare (100/m2). The thresholds in susceptible spring crops are:
ACTION: The risk of economic damage from leatherjackets this season is significantly higher than in recent years for susceptible crops in England and extremely high in Scotland. Fields with a history of leatherjacket damage 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. 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. Wheat Bulb FlySoil samples are taken during December, from sites considered to be at risk, to establish the number of Wheat Bulb fly eggs present. Weekly soil sampling is then carried out during January, February and March to monitor egg hatch and then plant invasion. Monitoring sites normally cover a range of soil types from East Anglia and Yorkshire. Pestwatch reports are produced to reflect weekly data and provide advice on timely application of Dursban WG. The advice provided also indicates when switching to dead-heart sprays would be most appropriate. LeatherjacketsNationwide assessments of Leatherjacket populations are undertaken annually by Dow AgroSciences UK. Soil samples are taken from over 100 representative sites, from the south coast of England, through the south and west Midlands, the north-west of England, Yorkshire and from the west of Scotland. The results of the surveys are expressed as the number of Leatherjackets per square metre and an indication of the potential for damage to susceptible crops is given. One Pestwatch report is published annually and is normally available in March, to coincide with the drilling of susceptible spring crops. Wheat Blossom MidgeSoil sampling to establish baseline populations of Wheat Blossom midge is done in April. Representative samples are taken from the key wheat growing areas of England and analysed for the total number of Wheat Blossom midge present. The data also reports the life cycle stage of the midge detected. During baseline sampling most midges are still in the overwintering cocoon stage. Further soil samples are taken during May and June. The purpose of these samples is to monitor progression through life cycle stages. Suitable weather conditions together with a higher proportion of midge present as pupae in the soil indicate an emergence of adults is imminent. As the situation, and hence potential risk, can change very quickly Pestwatch reports are issued as they are needed throughout May and June. Frit FlyAdult Frit fly are trapped, and their numbers monitored, by deploying water traps. The traps are initially set during early August and reset and monitored weekly for around six weeks. This gives an indication of the potential risk to susceptible crops from third generation Frit fly. Traps are normally placed in south-west England, the west Midlands, north-west England and North Yorkshire. Pestwatch reports are issued weekly during this time, indicating numbers caught, the potential risk and appropriate use of Dursban WG. Where numbers of adults are relatively low, but still sufficient to cause problems in emerging crops, the Pestwatch report will recommend the lower Integrated Pest Management rate of Dursban WG be applied. |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||