28Feb
Agri Chemical Update Autumn 2022
Words supplied by Bill Cabout, Ruralco Ashburton Store Manager
For the next three months we will look at the following: fodder crops, pre-emergence sprays on autumn sown crops, grass grub control in pasture, and use of gibberellic acid to increase pasture growth.
Fodder crops
Most sprays on fodder beet have been completed. If signs of disease appear such as rust, powdery mildew, cercosporin and ramularia leaf spot we can apply a fungicide. We now have a choice of two fungicides, Escolta (Cyproconazole/Trifloxystrobin) types with 42-day withholding period and Custodia (Tebuconazole/Azoxystrobin) with a 28-day withholding period.
Fodder brassica crops will need spraying with insecticides if the insect pressure gets too high. Early this season insect pressure was low. We haven’t seen many white butterflies flying in crops yet but when the rain stops, and we warm up again I am sure they will appear which means caterpillars in a few weeks’ time so an insecticide will need to be applied. We should also apply an aphicide to control any aphids present at the same time rather than having to come back later. We can either use older chemicals that will kill every insect, or we can use the IPM (Integrated Pest Management) approach using newer chemistry that targets the pests and leaves the beneficial insects alive.
Autumn sown crops
For crops planted after harvest, we need to look at drilling with either Diazinon Granules or Chlorpyrifos Granules to help control grass grub. Both Diazinon Granules and Chlorpyrifos Granules (Suscon Green) are in plentiful supply this season.
If there is a lot of trash, slug control is recommended especially if the crops have been irrigated. Ruralco has a range of slug baits available in store. The key to slug control is baits per square metre.
We need to make sure we control slugs and insect pests when we drill crops to ensure successful establishment of the new crop. If we don’t control slugs in time, we will have to re-drill the crop. It is cheaper to control the pests than to buy new seed and re-drill.
Depending on the crop, the use of pre-emergence sprays is important to control weeds going into the winter.
Wheat: If hairgrass is a problem, we must use Firebird or Invado. The choice of which depend on what other weeds are present as Firebird also has diflufenican in it. Diflufenican will help control some weeds that Invado alone doesn’t. These chemicals are often used with Asset (Terbuthylazine) as well to control a greater range of weeds. If wild oats are a problem Avadex Xtra can be used pre-sowing to help control them. This is an alternative if you have problems with controlling wild oats later. Ruralco also has Sakura a new herbicide from Bayer for controlling autumn germinating ryegrass, vulpia hairgrass, annual poa, soft brome and barley grass plus also gives suppression of ripgut brome, prairie grass and wild oats. This can be used instead of Firebird or Invado.
Barley: Again, Firebird or Invado can be used as above to control weeds pre-emergent.
Ryegrass: To control a range of annual grasses and other weeds Ethofumesate is used pre-emergence in both perennial and annual ryegrass.
Grass grub control in pasture
This is the time of year to control grass grub in pasture using Diazinon liquid. This must be applied to short pasture and needs to be washed in by at least 12mm of rain before it dries on the foliage for best results. This season we have plenty of stock, but it always pays to get your orders in early, so you do not miss out.
Gibberellic Acid
We can increase the grass growth on pasture by 30-60% within a 3-week period by using Gibberellic Acid during the autumn period. For this to be successful there must be sufficient fertility and moisture to support this extra growth. It is often applied with liquid nitrogen to help this. Both granular and liquid versions of Gibberellic Acid are available. It needs to be applied 3-5 days after grazing. We have liquid nitrogen available in 1,000L pods to go with the Gibberellic Acid.
With all the above scenarios talk to your Ruralco Representative for the best agrichemical options for you and your farming business.
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