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Cereal Pestwatch
Dow AgroSciences 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.
Subscribing to Dow AgroSciences' Agronomy Update & Pestwatch gives eligibility for 1 Crop Protection BASIS Point annually. To find out more about this service, please contact our Technical Hotline on 0800 689 8899, your local Dow AgroSciences representative or E-mail. For the most recent Wheat Blossom Midge, Leatherjacket and Wheat Bulb Fly Pestwatch Reports see below: WHEAT BULB FLYReport 4 In support of product stewardship of Dursban* WG, Dow AgroSciences in conjunction with ADAS, will be monitoring Wheat Bulb fly egg-hatch and subsequent plant invasion. This helps farmers comply with needs to accurately assess risk and thus optimize spray timings. Results of the HGCA-funded survey of Wheat Bulb fly egg numbers in England show 20% of fields sampled are above 250 eggs/m2. In Scotland from sampling conducted by Scottish Agricultural Colleges, the risk is considered to be low-moderate; here 30% of fields had Wheat Bulb fly populations that exceeded 100 eggs/m2. From this survey, fields in the main risk area have been selected which have high or very high egg numbers present. Progression of egg-hatch will be monitored weekly between now and mid-February. Results Egg-hatch is progressing rapidly in East Anglia and also progressing in north Lincolnshire. There has been some initial plant invasion (<5%) at the Suffolk and Lincolnshire sites. Where larvae have been found they are at the first instar. On these sites plant invasion is still too low to move to dimethoate. We have also received one report of plant invasion in South Cambridgeshire. No egg-hatch as yet at the Yorkshire site; Scottish Agricultural Colleges have also confirmed egg- hatch has not started as yet in Scotland.
Be prepared to apply Dursban WG at 1.0 kg/ha in 200 to 1,000 litres per hectare of water.
In at risk fields, apply Dursban WG at the first available opportunity as tiller survival will be very important. In the event of a prolonged egg-hatch a repeat application of Dursban WG may be required, particularly on organic soils.
If necessary, Dursban WG can be applied to frosty ground but should NOT be tank mixed. Do not apply to frozen soil where rain could result in run-off to water courses.
Equity* also has recommendations for Wheat Bulb fly.
Use low drift nozzles and extend buffer zones to preserve Dursban WG use!
When spraying Dursban WG or Equity for wheat bulb fly:
WHEAT BLOSSOM MIDGEThird Report Pupation has been recorded at five out of eight monitored sites (62.5%). The mean percentage pupation was 8.6% (range 0-40.0%). No pupae were found at the Cambridgeshire sites or at Bishopstone in Wiltshire. Adult male midges have been caught in pheromone traps in a number of locations and in some instances numbers have exceeded 100/trap/day. In general, counts of female midges in crops or on yellow sticky traps have been low. Most areas have had rain recently. The weather forecast is for a period of warm weather, ideal for midge migration. It is, therefore, important to continue to monitor crops as many are still not beyond the susceptible stage.
Can I mix a fungicide with Dursban WG? Although “best” timings for both may be compromised we have tested a number of fungicides for physical compatibility. These include:
Avoid tank mixing if the crop is under stress. We do not support tank mixes when spraying Equity* for Blossom midge even where physically compatible. Anecdotal Comments Reports from around the country indicate that there are many flying yellow wheat blossom midges and saddle gall midges (See previous report). Orange Wheat Blossom midge numbers are reported to be lower and more localised. There have been hotspots reported particularly from Essex to Hampshire, although some crops are nearing or beyond the critical growth stages. However, many crops are at susceptible stages, and they need to be monitored for the presence of female midges on warm still evenings. The recent rains may well produce a flush of pupation and emergence of adults. * Trademark of Dow AgroSciences LLC All brand names are trademarks of manufacturers for which proprietary rights may exist
LEATHERJACKETSAnnual report - April 2011 Each autumn Dow AgroSciences commission ADAS and the SAC Auchincruive to survey leatherjacket numbers in grassland sites across England and Scotland as part of its commitment to the stewardship and product support for users of Dursban* WG and Equity*. The latest survey indicates a low-medium risk in Scotland. In England there are low populations of leatherjackets. The only exception to this is North Yorkshire where mean numbers increased by 126% in comparison with 2009 and 56% of sites were above 50/m2. All sites sampled were in grassland. Results give an indication to the risk to susceptible crops including spring barley and sugar beet. SCOTLAND A total of 219 grass fields were sampled in west and central Scotland between November 2010 and March 2011. Leatherjacket populations in these areas have fallen from the very high levels observed last year as only 39% of fields tested had levels over 60/m2 compared to 67% in 2010. Despite the potential threat to spring cereals out of grass in some areas, leatherjacket populations can vary, not only from area to area but also within an area and from field to field. Hence it is essential that an assessment of leatherjacket densities is conducted prior to deciding whether any insecticide application is necessary. For the season in question, the risk is highest in the areas of Argyll, Ayrshire and Bute. ENGLAND A total of 49 sites were sampled in the three key regions shown below during autumn 2010. The overall mean leatherjacket population per site was 18.1/m2 in 2010 compared with 15.1/m2 in 2009, 7.4/m2 in 2008 and 15.7/m2 in 2007. The long-term mean for all sites in the period 1993-2010 is 61.2/m2. Mean leatherjacket populations by region in 2010 were 8.9/m2 in the midlands and western area, 32.5/m2 in northern England and 6.0/m2 in southern England. Northern and Southern regions increased by 81% and 200% respectively when compared with 2009. However the population is still low and significantly below the figures for the years between 2004 and 2006. The highest population for individual fields in 2010 was at Bishop Thornton in North Yorkshire where 139 leatherjackets/m2 was recorded. North Yorkshire holds the highest risk this spring as mentioned earlier. Leatherjacket Damage Thresholds
The risk of economic damage from leatherjackets in 2010 in Scotland is low-medium. Because leatherjacket populations will vary from field to field, risks should be assessed before treatment is made. Leatherjackets are very resilient to cold and frost; under such conditions they react by reducing their feeding ability until the soil warms up again. High infestations should be treated as soon as ground conditions permit and when leatherjackets are feeding. Check fields carefully. We have received reports of bibionid fly larvae in grassland in Scotland. Bibionids or fever fly grubs occur in very dense clumps in soil, and if they are wrongly identified as leatherjackets they may cause unnecessary concern. In England the risk is low. 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. 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/ha applied in 200 to 1000 litres of water. If using Equity* the recommended rate is 1.5l L/ha 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. Use plant protection products safely. Always read the label and product information before use. * Trademark of Dow AgroSciences LLC Dursban WG contains chlorpyrifos Equity contains chlorpyrifos
Wheat Bulb FlySoil samples are taken during the autumn from sites considered to be at risk, to establish the number of Wheat Bulb fly eggs present. From this survey, fields are selected which have high or very high egg numbers present. Weekly soil sampling is then carried out on these selected fields 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. |
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