Monitoring for weeds and insects helps forage brassicas grow optimally
Keeping weeds and insect pests under control within high-value forage brassicas crops allows crops to reach their full potential. The more dry matter (DM) per hectare (ha) a crop produces at maturity, the more economical the cost of producing DM on a cents per kilogram (kg) basis.
This is the advice of Nufarm Technical Specialist Paul Addison. He says one of the best things to do at this time of the year is to monitor forage brassica crops closely and as often as possible. “Brassica seedlings often need help establishing to avoid being outgrown by weeds or being eaten by insects.”
Applying a pre-emergence herbicide, such as Director CS, can help reduce early weed pressure.
If required, post-emergence herbicides give the best results when applied to actively growing small seedling weeds before the crop canopy closes. These herbicides are typically applied three to six weeks after sowing.
To get the timing right, Paul recommends checking crops about three weeks after sowing to determine what weeds are present and to organise spraying, if necessary. “This helps ensure you hit the weed seedlings at the correct stage which is two to eight true leaves. The crop will typically have two to four true leaves by week three.”
Nufarm's post-emergence herbicide, Prestige can be used in all forage brassicas to control a range of broadleaf weeds. Paul says it is particularly useful against black nightshade and fathen.
As well as controlling seedling summer grass, a grassweed herbicide containing clethodim is effective on annual and perennial ryegrass and helps ensure new pasture sown after the brassica crop is free of nuisance grass species.
The risk posed by insect pests is usually highest in the early stages of crop establishment. Seedlings and young plants are vulnerable to pest infestation and once they have been affected, it’s difficult to reverse the damage. For this reason, a well-timed insecticide can help keep pest numbers under control and reduce their impact if signs of feeding appear. To better understand when to apply a treatment, Paul recommends being proactive and monitoring the crop regularly.
Insects including springtails, aphids, Argentine stem weevil, diamond back moth, white butterfly caterpillars, leaf miner and Nysius (wheat bug) can all reduce forage brassica DM yield. Paul says Nufarm’s Attack insecticide will effectively control these insect pests. As it offers a wide spectrum of control, farmers only need to buy, store, handle and apply one product to manage an insect infestation.
Alternatively, Kaiso WG is registered for control of cutworm in forage brassicas, as well as the caterpillars of white butterfly and diamond back moth.
Your local PGG Wrightson Technical Field Representative can assist in developing a spray programme for your brassica crops.
Registered pursuant to the ACVM Act 1997, Director CS #P009222, Prestige #P007823, Attack #P002912 and Kaiso WG #P008819. Always read the registered label before use.
