Weed control management options in winter rape

Transcription

1 Technical Note TN647 Novber 2012 Print_All Weed control managent options in winter rape Summary Winter Rape is an important break crop to control grass weeds such as brome and black-grass. Metazachlor forms the backbone of weed control in winter rape. Best weed control comes from pre-ergence applications as post ergence treatments for broad leaved weed control are limited. New herbicide technologies such as Cleranda for use on Clearfield rape varieties offer hope for post ergence weed control. Product stewardship for metazachlor, propyzamide and carbetamide is important to meet EU Directives on water quality. Increasingly winter rape is being established on wide rows where early weed control is more important. Introduction Weed managent in the rotation Winter Rape in the North of the UK traditionally follows winter barley which allows early establishment of the crop. Winter rape also provides the main break crop within the UK for managent of grass weeds such black-grass, bromes and rye-grass. Increasingly in parts of the UK black-grass has become resistant to the common cereal herbicides such as the ALS inhibitors and other herbicide groups. At present this has not been recorded within the small Scottish black-grass population. Weed control in winter rape is built around three herbicides, metazachlor, propyzamide and carbetamide. Although widely used there is no recorded weed resistance to these herbicides. However the wide use of these products is coming under the spotlight due their leaching into water courses at levels that breach EU Directives on water quality. Their movent into water is due to their autumn/early winter application commonly coinciding with peaks of high rainfall. As a result there is an increasing need to follow the stewardship guidelines built around the use of these herbicides to limit their impact on the environment and retain approval for these important herbicides. SRUC West Mains Road, Edinburgh EH9 3JG. SAC Consulting is a division of SRUC. SRUC is a charity registered in Scotland, No. SC003712

2 Table 1 Winter Rape Herbicide Product Profiles 2012 Product Active Ingredient Timing and notes -ergence of weed and crop Centium/(Cirrus) Centium Plus Twin pack 360g/l clomazone Typically l/ha Metazachlor + Clomazone 5.0 ha pack= 1.0 l/ha metazachlor +0.2 l/ha clomazone -ergence or early post ergence of the weeds and crop Butisan S, Sultan 50SC & many other generics Nimbus Novall/Naspar TDi 500g/l metazachlor Typically 1.5 l/ha 250 g/l metazachlor g/l clomazone Typical dose 2.0 l/ha to max of 3.0 l/ha 400g/l metazachlor g/l quinmerac Typically 2.0 l up to max of 2.5 l/ha Oryx 333 g/l metazachlor + 83 g/l quinmerac Springbok/Muntjac Shadow/Elk /Katamaran Turbo Teridox ergence of crop and weed Crawler Kerb Flo and others 200 g/l metazachlor g/l dimethenamid-p Maximum 2.5 l/ha 200 g/l metazachlor g/l dimethenamid-p + 100g/l quinmerac Maximum 2.5l/ha 500 g/l dimethachlor 2.0 l/ha 60% w/w carbetamide 2.5kg/ha 500g/l propyzamide l/ha. For black-grass up to 1.7 l/ha Note generics are 400 g/l propyzamide -ergence, tankmix with metazachlor to add cleavers and improved shepherd s purse. Can give transitory whitening of crops as it erges. Not on light soils or sands. Ensure seed is well covered. -ergence of the crop -ergence up until the crop chits which may be with 48 hours from drilling. Apply post from expanded cotyledon stage. Note it is only permissible to apply no more than 1000g/ha metazachlor/ha to the same field over a three year period. Do not apply pre- on broadcast crops or if heavy rain is forecast immediately after application -ergence of the crop. Good on cleavers and shepherd s purse, speedwells & groundsel. Same restrictions apply as with metazachlor. -ergence up until the crop chits which may be with 48 hours from drilling. Apply post from expanded cotyledon stage. Quinmerac adds cleaver control to two whorls and mayweeds to 4 leaves. Do not use on broadcast crops -ergence up until the crop chits which may be with 48 hours from drilling. Apply post from expanded cotyledon stage. Quinmerac adds cleaver control to two whorls and mayweeds to 4 leaves. Do not use on broadcast crops Apply pre/post ergence but best results pre of the weeds. Dimethenamid-p improves shepherd s purse control Do not apply to broadcast crops until crop is at two cotyledons Good post ergence control of chickweed, small shepherd s purse, RDN and speedwells. Same restrictions apply on applications as for all metazachlor containing products New from Syngenta. Similar weed spectrum to Metazachlor. Widely used in Europe. Very limited quantity for More likely in 2013 Apply from 15 th of October from 4 leaves, until end of Feb. Some residual activity on weeds up to all stages of grasses and seedlings of some other weeds. Useful product for black-grass control in cereal /rape rotation. Can be used in sequence with propyzamide for black grass control, Crawler first Apply from 1 st of October, 3 leaves on the crop when soil tperature dropping below 8 o C Lower rate when used in sequence with another graminicide to control volunteer cereals and grasses and chickweed is not a probl. Useful control of black-grass in rape/cereal rotation.

3 Table 1 Winter Rape Herbicide Product Profiles 2012 continued Product Active Ingredient Timing and notes Cleranda Dow Shield 400 SC Galera Laser Fusilade Max Falcon/Shogun Aramo Lentagran WP (EAMU) Fox (EAMU) 17.5 g/l Imazamox g/l metazachlor Must be used with Dash Adjuvant Rate 2.0 l/ha + Dash 1.0 l/ha 400 g/l clopyralid Max dose 0.5lt/ha 267 g/l clopyralid + 67g/l picloram Max dose 0.35 l/ha 200 g/l cyloxydim l/ha Use with approved adjuvant at 0.8% of spray volume 125 g/l fluazifop-p-butyl l/ha 100 g/l propaquizafop l 50 g/l tepraloxydim l/ha for Annual meadow grass control use the higher rate 45% w/w pyridate 2.0 kg/ha 480 g/l bifenox 1.0l/ha Only for use with Clearfield varieties from Monsanto and Pioneer. Best applied early post ergence at 2-4 leaf of crop. Good control of SU type weeds including chickweed, Shepherd s purse, charlock. Useful control of black-grass and volunteer cereals. (Note volunteers of Clearfield rape will not be controlled by ALS inhibitor herbicides) No autumn application. Used to control sow thistles mayweeds and groundsel. Apply from 2 leaves to flower bud visible. Used to target cleavers up to 15cm and mayweeds to 15cm. From expanded cotyledon to canopy closer. Volunteer barley requires lower rate than volunteer wheat. Apply using a FINE spray quality Apply from 1 leaf to before flower bud visible. Lower rates possible with experience to control volunteer cereals. Apply from expanded cotyledon to before flower bud visible. Grass weeds from 2 leaves. Lower rates possible with experience. Apply from expanded cotyledon to end of Novber or 9 expanded leaves which ever comes first. The only graminicide to give control of AMG. From 6-9 leaves and before st elongation. Useful control of cleavers, groundsel, speedwells small chickweed, bindweed and shepherd s purse. An expensive option. Apply before flower buds visible. For control of field pansy, red-dead nettle, poppy and speedwells. For crop safety reasons may be best to split dose to 2 x 0.5l/ha Establishment of the oilseed rape crop 1. Tillage. The optimum establishment period for winter rape in the north of the UK is from mid August to early Septber, usually following winter barley or occasionally spring barley. Traditionally, winter rape is established by ploughing and cultivation to produce a fine seed bed for drilling a small seed crop and allowing for ideal conditions for a pre-ergence herbicide to work effectively. This method also inverts any volunteer grain lost from the previous crop and any straw and trash. Increasingly winter rape is now being established through minimal tillage or no till techniques. This has been driven by the ever increasing cost of fuel, the need to drill large areas in a short window of time and changes in agronomic practice. These techniques vary from sophisticated one pass systs from Simba and Vaderstad to less sophisticated machines from Claydon or simple drills bolted to a sub-soiler. 2. Implications of minimal tillage to agronomy. The positive advantages of minimal or no tillage systs are well established such as improvents in soil structure, earth worms number and other soil invertebrates. However the disadvantage is that it can allow a build up of grass weeds such as annual meadow grass, bromes, rye-grass and potentially black-grass. Control of volunteer cereals may also have to be considered particularly in bouts behind the combine where grain losses can be high. Grass weeds can be controlled using a stale seed bed before drilling if time allows, although in the North of the UK this is rarely possible. An alternative is to rotationally plough in front of the rape crop. Minimal tillage regimes usually reduce the impact of broadleaved weeds which are surface germinators and rely on soil disturbance to germinate. Cleavers, however, can still be a probl as they germinate from depth. 3. Wide row spacings. The traditional syst for growing winter rape is ploughing after a cereal crop, cultivating and drilling on standard 30cm rows. Increasingly rape is being drilled on wider row spacing, of up to 50cm or even 60cm. Techniques include using conventional drill types but increasingly seed is being drilled using sub-soiler drill combinations sown directly into stubbles at wide row spacings. This improves soil structure as well as saving on fuel and time and minimises inversion of the soil thus limiting germination of weeds, particularly grasses. When considering planting on wider rows it is important to reduce the seed rate to avoid over crowding in the row, (see figure 1). When considering a seed rate for planting on wide rows it is important to think in terms of plants/metre row length rather than kg/ha. HGCA sponsored trials have shown that, for planting at 50cm row spacing at an end of August, you should aim to establish plants/m row length in good soil

4 conditions increasing even further on poor soil types and with later drillings. As an optimum coming out the winter aim for plants/metre row length. Good weed control is essential when planting on wide rows as the crop is less competitive for a longer period until the leaves meet across the rows, (see figure 2 below). ergence Weed Control Herbicide choice. The choice of herbicide for broad leaved weeds in the winter rape crop is limited, see table 1. The table shows that metazachlor, either as the straight product or in co-formulation, forms the backbone of weed control in rape. Metazachlor based products, either as the straight product or the co-formulations should be applied within 48 hours of drilling, or before the seed chits, which may be longer in a dry seed bed. It gives a good start to annual meadow grass, chickweed, mayweed, shepherd s-purse and groundsel control. If conditions are unsuitable at this pre-ergence timing, either because of very dry soil conditions or heavy rain is forecast then metazachlor or co-formulations of metazachlor should be applied when the crop is at the fully expanded cotyledon stage. The only exception is any application containing clomazone either as the straight or in co-formulation which must be applied pre-ergence of the crop. At the later timing you are reliant on weeds having no more than cotyledons or a single leaf for good effect. Some weeds such as shepherd s purse and poppy are not controlled post-ergence. Doses of metazachlor depends on timing, soil type (the lighter the soil the lower the dose) and weed species expected (higher doses are needed for shepherd s purse and poppy, for example). The pre-ergence treatment of shepherd s purse with metazachlor is an essential treatment for this weed if it is a serious probl, as later treatments are often not effective. To improve shepherd s purse control, mix metazachlor with Centium or use Springbok or Nimbus/Naspar TDi. (The weed control spectrum of individual products are shown in table 2.). Metazachlor + dimethenamid-p: (Springbok/Muntjac) contains 200 g/l metazachlor with the addition of 200 g/l dimethenamid-p, (DMTA-P), recommended at 2.5 l/ha. The DMTA-P has root and shoot up take compared to just root uptake from metazachlor. This mix gives improved pre-ergence residual control of geraniums and poppy, and pre-and post-ergence activity on crane s bill. It also has useful activity on shepherd s purse preergence to 1 true leaf, which is more flexible than straight metazachlor or Novall/Naspar TDi. (Note Clomazone based products must only be used pre-ergence of the crop). Novall/Naspar TDi has 400 g/l metazachlor and 100 g/l quinmerac. Quinmerac is very soluble but is highly bound to the soil and taken up by leaves and roots and compliments the root uptake of the metazachlor. Compared to straight metachlor, it gives a little more activity on fumitory, improves cleaver control pre-ergence to cotyledon stage, and gives better control of poppy, red-dead nettle and speedwells. Shadow/Elk combines the three active ingredients, metazachlor, dimethenamid-p + quinmerac to give root, shoot and leaf uptake giving more consistent pre-ergence and post ergence control of probl weeds. Control of cleavers is recommended up to 2 whorls, although trials suggest cleavers up to 6 whorls may be controlled, chickweed up to 2 leaves, crane s bill up to 1 leaf and better control of shepherd s purse and poppy than straight metazachlor applied pre-ergence or at expanded cotyledon stage of crop. There is a label recommendation of a split dose of 1.5 l/ha pre-ergence followed 1.0 l/ha post ergence. This will give more prolonged control of poppy. Nimbus has 250 g/l metazachlor + 33 g/l clomazone and is an alternative pre-ergence only option where shepherd s purse and or cleavers are the main weeds. Interestingly, it will also control hedge mustard which is a probl in some parts of the borders and northern England. A more flexible option may be to mix up your own Nimbus with a tank-mix of clomazone with straight metazachlor or use Centium Plus. Much will depend on the relative pricing. This has proved a useful alternative to improve control of cleavers, shepherd s purse and red-dead nettle amongst a wide range of other broad-leaf weeds plus annual meadow grass. Nimbus/Centium/Cirrus may only be used preergence of the crop. There can be a transient discolouration of the crop, but it recovers rapidly. Note the use of clomazone has been found to sensitise grass weeds such as volunteer cereals, brome and black grass to following graminicides. Note there are important product stewardship restrictions that appear on all labels for products containing metazachlor. The labels state that NOT more than 1000 g/ha metazachlor may be applied in a three year period on the same field. It is a rolling three year period. Before applying metazachlor check how much has been applied in the previous two years. All applications made after January 2010 must be considered. ergence weed control Cleranda: Cleranda from BASF is designed for the exclusive use on Clearfield branded varieties of winter rape from Monsanto and Pioneer. Cleranda contains imazamox and metazachlor for use post ergence up to 9 true leaves, (GS19). Imazamox is an ALS inhibitor, more commonly found in the pea and bean herbicide Nirvana. It gives good post ergence control of typical weeds associated with this group of herbicides. Importantly this includes shepherd s purse, chickweed and fumitory and volunteers of non Clearfield varieties. Note it is important to clearly mark which fields contain Clearfield rape as the volunteers of these varieties in following cereal crops will not be controlled by other ALS inhibitors eg tribenuron. Growers adopting the Clearfield technology generally have specific weed probls to control, as choosing these varieties will incur a small yield penalty because, as yet, they are not as high yielding as conventional varieties. The main points about Cleranda are:- Complete crop loss will result if Cleranda is applied to non- Clearfield crops Two complentary active ingredients - imazamox (contact) and metazachlor (residual) Imazamox component is a new use in oilseed rape Combines herbicide and seed technology Clearfield varieties have hybrid vigour Later application timing than other broad-leaved weed residual herbicides Controls probl weeds Provides control of conventional volunteer oilseed rape Provides control of volunteer cereals Optimum application timing GS14 (GS11-18) Cleranda is recommended for use with adjuvant Dash at 1 l/ha Broad spectrum weed control

5 Figure 1. Rape established on 50 cm spacing Figure 2 Rape grown on wide row. Weed control critical on wide rows as poor inter-row competition

6 Table 2 Weed control from herbicides in winter rape with weed spectrum Weeds Herbicides Metazachlor Metazachlor / Quinmerac Metazachlor / dimethamid Metazachlor / dimethamid / quinmerac Metazachlor / clomazone Metazachlor / imazamox 2 (Cleranda) Clomazone Bifenox (EAMU) Clopyralid Clopyralid + Picloram Propyzamide Carbetamide Annual Mercury MS 1 Barley, Volunteer MS 1 Black grass S MR MS S Black-Bindweed MS MS Bugloss Charlock S Chickweed, Common S S S S S S S S Cleavers MR S S S S MS 1 S MS S Cornmon Chamolmile S Cranesbill, Cut-leaved MR MR S S MR MS S Cranesbill, Round leaved S S MR MS Cranesbill, Small flowered S S MS Dead nettle, Red S S S S MS S Fat Hen MS MS S Fools Parsley S Forget-me-not, field S S MS MS S MS Fumitory MS S Gromwell, Field Groundsel S S S S MS S S Hedge Mustard S Hp nettle / Day nettle Knotgrass MS S Marigold, cornmon S Mayweed spp. S S S S S S Mayweed, Scented S S S S S Meadow grass, Annual S S S Mustard, Hedge S Mustard, White S Nettle, Small MS S Nipplewort Oilseed Rape, Volunteer Pansy, Field MS MR MR MR MS S Parsley Piert S S S S

7 Table 2 Weed control from herbicides in winter rape with weed spectrum continued Weeds Herbicides Metazachlor Metazachlor / Quinmerac Metazachlor / dimethamid Metazachlor / dimethamid / quinmerac Metazachlor / clomazone Metazachlor / imazamox 2 (Cleranda) Clomazone Bifenox (EAMU) Clopyralid Clopyralid + Picloram Propyzamide Carbetamide Parsley, Fool s S Penny-cress, Field MS Poppy, Common MS S S S S S MS MS Runch S Shepherd s Purse S S S S S S S MR Sowthistle, Perennial S MS S Speedwell, Common Field S S S S S S MS S S S Speedwell, Ivy-leaved S MS S MS S S Spurrey, Corn Thistle, creeping Wheat, Volunteer MR MR MR 1 Weed growth stage Crop growth stage or cots or cots or cots or cots and and post

8 Emergence Weed Control of Volunteer Cereals and Grasses Winter rape is commonly grown as break crop in a cereal rotation to break the cycle of cereal pathogens and also to control difficult / pernicious weeds such as brome and black-grass. Wherever possible, volunteer cereals and grass weeds should be sprayed off with a non-selective herbicide in the stubble prior to drilling. However, it is recognised that in the North of the UK, where the turn around time between harvesting the cereal crop and establishing the rape crop is often tight, this is not always possible and the application of a specific graminicide is the usual course of action. The main options for grass and volunteer cereal control are shown below:- Table 3 Options for grass and volunteer cereal control on winter rape (Note that Avadex is pre-ergence other products post-ergence) Herbicide TrIalate (EAMU) Avadex. - Propyzamide Carbetamide Propaquizafop Falcon/Shogun Fluazifop-p-butyl Fusilade Max Cycloxydim Laser Quizalofop-P-ethyl Pilot Ultra Quizalofop-P-tefuryl Panerex Tepraloxydim Aramo Barley - S S S S S S S S Wheat - S S S S S S S S Oats S Annual Meadow Grass S S S MR R R - - S Barren Brome S S S S S S S - S Blackgrass S S S Resistance increasing > Wild Oat S S S S S S S S s Italian Rye Grass - S S Ms S S S S - Perennial Rye Grass - S S S S S S s - Propyzamide, e.g. Kerb Flo 500 and carbetamide, e.g. Crawler are applied post ergence to control grass and a limited range of broadleaved weeds such as chickweed. They are more widely used in England as strategies to control black grass in the rotation. Importantly there is no known resistance within black grass populations to these products. The best timing for both products is when soil tperatures at 10cm reach 10 C and are falling and where there is sufficient soil moisture for weed uptake. As both products have caused water quality probls proper stewardship is important. Thus:- They should not be applied when the drains are running or likely to run for 7 days post application. They should not be applied to field with slopes >5 % The field should not be bordered by a water course unless the field has a 6m grass buffer zone The field should not be sub soiled below the plough layer The field should not have been mole drained with last 6 months No rain is forecast within next 48 hours Author: Mark Ballingall, Weeds and Herbicide Specialist, Applied Practice Team SAC Consulting, Sandpiper House, Inveralmond Industrial Estate, Perth PH1 3EE Funded by the Scottish Government as part of its Crop Health Advisory Activity