Words by Bill Cabout, Ruralco Ashburton Store Manager.
For the next three months, we will look at the following: autumn sown arable crops, barley grass control in pasture and weed control in lucerne.
Autumn Sown Arable Crops:
Most autumn sown crops have already been planted by now. Seed treatment only persists for a certain amount of time after planting, until the start of tillering (GS21). Crops drilled before mid-April will now not be protected from aphids. Aphids can carry the disease Barley Yellow Dwarf Virus (BYDV) which, if your crop gets at this early stage, will severely damage yield. It is a good idea to apply an approved insecticide – even if aphid numbers are low – as this often proves to be good insurance. Depending on what the aphid numbers do (influenced largely by weather; cold and wet means less aphids), you may need to follow up three weeks later with another spray. A good way to check up on aphid numbers is to check the Lincoln Suction Trap data on the FAR website once they start updating stats.
This year there are large numbers of grass grub about, and this can decimate a crop before you realise. Diazinon granules at drilling will provide up to five weeks’ protection from grass grub, meaning this protection will soon be wearing off. Check your crops and if grass grubs are found close to the soil surface, your crop may need spraying with Dew to control numbers. This is ideally put on during rain, so it washes into the soil where the larvae are.
If you have drilled with Suscon Green, you should be covered for the life of the crop.
Slugs have been an ongoing issue in some crops throughout autumn. Monitor your crops closely and if need be, apply slug bait.
If you have some early weed strike that has not been controlled by your pre-emergent spray, it is ideal to clean this up while the weeds are small. Which product to use is determined by what weeds are present. Talk to your Ruralco representative for the best options.
For the control of brome grass, we can use Rexade (Pyroxsulam + Arylex). This combination controls wild oats, rye grasses and brome grass, as well as many significant broadleaf weeds such as fumitory, chickweed, cleavers, field pansy, speedwell, shepherds’ purse, white clover, and volunteer linseed. It can be applied from GS13 to GS31. If applying to control brome, Rexade can be applied twice, whereas for the control of other weeds it should only be applied once. The rate used is 100g/ha plus 250ml non-ionic surfactant/100L water and is available in a 2kg pack. Please check the withholding periods for planting following application, as on some crops it can be up to 12 months. This product is for wheat and triticale only.
If you are planting wheat and barley during the winter months, you can use Firebird or Invado pre-emergent up to the July 31. After this date, it doesn’t work as effectively as weeds will grow too fast.
White Clover Seed Crops
Kerb 500F can be applied to white clover seed crops during the winter months from June to August for the control of grass weeds and some broadleaf weeds. Weeds not controlled by Kerb can still be controlled by other products depending on weed spectrum during July and August. Contact your Ruralco representative for options.
Ryegrass Seed Crops
With the good growing conditions this year, an early post-emergence spray is worth looking at to control any weeds that have appeared in the paddocks. What to use will depend on your weed spectrum. In early spring you will need to apply an herbicide to control wild oats. Contact your Ruralco representative for options.
Barley Grass Control
For control of barley grass in your pastures, apply Ethofumesate (Nortron) at 4L/ha. Timing is important when applying this herbicide product. Application should be after the main germination has occurred, following autumn rains. There is residual activity from about 8-10 weeks, therefore timing is essential to ensure that the residual activity is effective during the spring germination period of the weed. Ideally apply during the last week in June or first week in July.
Weed Control in Lucerne
The ideal time to control weeds in lucerne is during the winter dormancy period – before the onset of spring growth – so there is no crop damage or suppression. Paraquat is an ideal broad-spectrum weed control for lucerne as it provides excellent control of annual and many perennial broadleaf weeds, plus most grass weeds. Paraquat can be mixed with a residual herbicide, such as Atrazine, to provide season-long weed control. Atrazine should not be applied to stands less than 12 months old. Terbuthylazine (Asset) can also be used but can only be used on stands older than 24 months. Stands 6-12 months old should be sprayed with Paraquat only. Any weeds not controlled by this can be looked at again in the spring.
Last year, a new herbicide, Chateau, was released for weed control in lucerne. This can be used on stands over 12 months old and should be applied to bare soil to get the best results. Because of this, our recommendation is that Paraquat should be applied with it. If the stand has a lot of leaf, you may need to spray Paraquat first and then come back with Chateau in a few weeks to get the best out of it. See your Ruralco Representative for your best option.
Monitoring Stored Grain
Monitoring grain during storage is a valuable tool in maintaining quality. This becomes more important the longer the grain remains in storage, as, in the early days, deterioration in seed quality is slower and insects are sparser and not as easily noticed. Temperature and seed moisture content are important indicators of grain quality that influence insect and mould activity. Once grain is in storage, monitoring for insects and mould once a month will give early notice of any problems occurring, and action can then be taken to control them.
For further information on any of the above, please contact your Ruralco representative of ask to speak with one of our friendly team.