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Words by Bill Cabout, Ruralco Ashburton Store Manager

Winter is fast approaching and for the next 3 months our focus will be sown arable crops, barley grass control in pasture and weed control in lucerne.

Autumn Sown Arable Crops:

With seed treatment only persisting 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 Barley Yellow Dwarf Virus (BYDV), a disease that can severely damage yield in a crops early stages. It is a good idea to apply an approved insecticide even if numbers of aphids are low to provide good insurance. Deciding if you need to follow up three weeks later with another spray will depend on aphid numbers, considering that these can be dependent on the weather e.g., cold and wet weather means less aphids. A good way to check up on aphid numbers is to check the Lincoln Suction Trap data on the FAR website.

This year there are large numbers of grass grub about that can decimate a crop before you realise. Diazinon granules at drilling will provide up to five weeks’ protection from grass grub so this protection will be wearing off by now. Check your crops and if you find grass grubs close to the soil surface, your crop may need spraying to control these with Diazinon 600. 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. Talk to your Ruralco Representative for the best options.

For the control of brome grass, we can use Rexade. It has the same active ingredient 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 one application will suffice. 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 is up to 12 months currently 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 30 July. After this date, it does not 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 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. Contact your Ruralco Representative for options.

Ryegrass Seed Crops:

As most ryegrass seed crops were in the ground early this year, an early post emergence spray is worth looking at to control any weeds that have appeared in the paddocks. The choice of spray depends on your weed spectrum. In early spring you will need to apply a herbicide to control wild oats. Contact your Ruralco Representative for options.

Barley Grass Control:

For control of barley grass in your pastures, apply Nortron/Claw at 4L per ha. Timing is important when applying these products. The herbicide application should be after the main germination has occurred following autumn rain. There is residual activity from about 8-10 weeks, therefore timing is essential to ensure 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 to reduce 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 only on stands older than 24 months. Stands 6-12 month’s old can be sprayed with Paraquat only. Any weeds not controlled by this can be looked at again in the spring.

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.

For further information please contact your Ruralco Representative.