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Crop Crack 9.10.10
By Wendy Fearon
A start has been made to autumn drilling but there is very little in the ground yet. There is still a good choice of autumn herbicide products available but most of these must go on early. For NI cereal growers, good control of annual meadow grass remains the key issue as this weed is most damaging of all in cereal crops. The most effective timing for AMG control is pre-peri emergence.
Chlorotoluron (CTU) is of the same family of chemistry as IPU, and has identical mode of action and very similar spectrum of weeds controlled, including AMG, chickweed, mayweed & groundsel. Its’ principal limitation is certain varieties of winter barley & winter wheat are not tolerant to CTU, so can only be used on named varieties (check approved variety list). In addition, only use when the seed is well covered and the crop is not under any stress.
Flufenacet offers the widest window for good AMG control – it is very residual so will remain active for an extended period after application, controlling from pre-emergent through to beginning of tillering.
Iodosulfuron & Mesosulfuron (both sulphonyl-ureas, SUs) will control AMG well into mid-tillering, but have contact activity only, therefore requiring all the AMG to be emerged for control to be satisfactory, so really can only be used from early spring onwards. (In addition these actives can only be used on winter wheat, not winter barley or winter oats.)
Pendimethalin (PDM) is also very active on AMG, but pre-emergent only. It is much less soluble than IPU, so persists for longer in the soil. PDM also has a much wider BLW spectrum than IPU.
Diflufenican (DFF) is another widely used active in the autumn; it is residual and has a wide spectrum of BLWs controlled, taking out larger emerged BLWs than many other residuals, but has no AMG activity whatsoever.
Be aware that the length of persistency of any herbicide product that has residual activity is inversely related to soil temperature-the lower the temperature the longer the duration of its persistency. As soils cool over the coming weeks so product performance will improve.
Flufenacet and CTU were the most widely used actives for controlling AMG in the 2009 season in NI. This active also gives good activity on brome and perennial rye-grass when used at its’ maximum rate. CRYSTAL contains flufenacet and pendimethalin and can be used on all varieties of winter barley & wheat. BUCKLER contains CTU & DFF. Where the variety list allows this product should be tank-mixed with the CRYSTAL. Its inclusion will extend the spray-window of CRYSTAL, allowing larger weeds to be controlled than if the CRYSTAL were used alone. The CTU will also bring groundsel activity to the mix, whilst the DFF will broaden the spectrum of emerged BLW controlled, including chickweed & mayweed. Only use when the seed is well covered, and not subject to stress as a result of waterlogging or frost Products containing chlorotoluron have varietal restriction and it is important to check your cereal variety when considering product choice. LEXUS CLASS is still the only product for use on winter oats.
Cereal Pests
The weather has been favouring slugs and damage has already been detected in winter oilseed rape. Slug pellets are best applied in damp conditions as this is when the slugs come to the surface. Crops are particularly vulnerable to slugs up to GS12 beyond this stage they can usually grow away from any further damage.Where wheat crops have still to be sown a fine seed bed will reduce the risk of slug damage.
Grain Store Hygiene
We have had a number of enquiries over the last couple of weeks with regard to grain store pests.Reldan can be used in barley,wheat,oats,rye and triticale in store. Grain will lose weight, reduce in nutritional value and be of a lower quality if left untreated. Pest activity can also lead to heating and development of moulds. To apply RELDAN for grain conveyor rates below 5 tonnes per hour, apply 20ml Reldan in 1.5litres of water per tonne of grain. At rates above 5 tonnes per hour apply 20ml Reldan on 0.75 litres of water per tonne of grain. It is important to note that moisture content of the grain is kept at or below 15%.
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