Words 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) which has a 42-day withholding period, and Custodia (tebuconazole/azoxystrobin) which has a 28-day withholding period.
Now is a good time to consider applying insecticides to fodder brassicas to prevent damage from both white butterfly and diamond back moth caterpillar. We should also consider applying an aphicide to control aphid populations at the same time, rather than having to come back and treat 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 pest species and protects the insects that benefit crop growth and production.
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, we need to look at slug control, especially if the crops have been irrigated. We have a range of slug baits available in store. The key to slug control is ensuring an effective bait per square meter ratio.
We need to control slugs and pest insects when we drill crops to ensure successful establishment of the new crop. Without this measure we may see slug infestations that become untreatable, and the crops will have to be re-drilled. It is more time and cost efficient to control the pests than to have to buy new seed and re-drill.
Depending on the crop we need to look at the use of pre-emergence sprays to control weeds going into the winter.
Wheat: If hairgrass is a problem, we must use Firebird or Invado pre-emergent herbicide spray. Both are effective treatments but the choice of which to use will be influenced by the other types of weeds present, as Firebird contains diflufenican as well. These chemicals are often used with Asset (terbuthylazine) for control of a greater range of weeds.
If wild oats are a problem, Avadex Extra can be used pre-sowing to help control them. This is an alternative to controlling wild oats later. We also have Sakura, a new herbicide from Bayer, for controlling autumn germinating ryegrass, vulpia hairgrass, annual poa, soft brome and barley grass, plus it 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 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 optimal results. This season we have plenty of stock, but as always, it always pays to get your orders in early, so you don’t 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. Gibberellic acid is often applied with liquid nitrogen to help ensure this. We have liquid nitrogen available in 1000L pods to go with the gibberellic acid, which is available in both granular and liquid formulas. The treatment needs to be applied 3-5 days after grazing.
With all the above scenarios, talk to your Ruralco representative for the best options for you and your situation.