Words by Bill Cabout, Ruralco Ashburton Store Manager
For the next 3 months, we will look at the following: autumn sown arable crops, barley grass control in pasture and weed control in lucerne.
Autumn Sown Cereal Crops
Most autumn sown crops have already been planted. Seed treatment only persists for a certain amount of time after planting until the start of tillering (GS21). Those 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 numbers of aphids are low as this often proves to be good insurance. Depending on what the aphid numbers do (influenced by weather; cold and wet means less aphids) will decide if we need to follow up 3 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 uploading their findings.
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 5 weeks’ protection from grass grub so this protection will also be wearing off. Check your crops and if you find grass grubs close to the soil surface your crop may need spraying with Dew to control these. This is ideally put on during rain, so it washes into the soil where the grubs 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 the autumn. Monitor your crops closely and if need be, apply more slug bait.
If you have some early weed strike not 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.
For the control of Brome grass, we can use Rexade. It has the same active as Simplicity (Pyroxsulam) plus the addition of 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 it can be applied twice, otherwise once only. 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 crops as it can be up to 12 months on some crops. 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 30th July. After this date, it doesn’t work as effectively as the weeds grow too fast.
White Clover Seed Crops
Kerb 500F or Fiera can be applied to white clover seed crops the winter months from June to August for the control of grass weeds and some broadleaf weeds. Weeds not controlled by kerb can be controlled by various products depending on weed spectrum during July and August.
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 depends on your weed spectrum. In early spring you will need to apply a herbicide to control wild oats.
Barley Grass Control
For control of Barley Grass in your pastures, apply Ethofumesate (Nortron) at 4L per ha. Timing is important when applying these products. The timing of the herbicide 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 period of spring germination 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 the 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. Terbuthylanzine (Asset) can also be used but can only be used on stands older than 24 months. Stands six to 12 months old can be sprayed with paraquat only. Any weeds not controlled by this can be looked at again in the spring.
This year a new product, Chateau, has been released for weed control in Lucerne. This can be used on stands over one year old and need to be applied to bare soil to get the best results, so paraquat needs to 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 a few weeks later to get the best out of it.
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 because deterioration in seed quality early in storage is slower, and insects are sparse and not 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 these problems.
With all the above scenarios talk to your Ruralco representative for the best options for you and your situation.