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Post-emergence weed control in brassicas

Post-emergence weed control in brassicas

Post-emergence weed control in brassicas

As farming businesses strive for improved production and better returns, gaining the best yields from crops for feed has become increasingly important.

Pycus Encaps® (Pycus) from Arxada has been assisting New Zealand farmers in the battle against weeds for over 15 years, having been developed and trialed in this country through Arxada’s (formerly Lonza) in-house formulation and field science team.

While a pre-emergent product like Ombre® is ideal for managing weeds before they come out of the ground, sometimes due to conditions or timing, weeds escape being controlled and a post-emergent herbicide application is required. This is where Pycus is a good fit. It controls several broadleaf weeds in forage brassicas including spurrey, amaranthus, fathen, nettle, and thistles. Table 1 provides an indication of the levels of control that can be achieved.

The best results are obtained when Pycus is applied to young, actively growing weeds, with 2 to 8 true leaves. Note, the stage of the crop is not important with brassica crops showing good tolerance to Pycus at all growth stages. If there is a split crop germination, Pycus can be used as the seed grows through an application. Think weed size, not the crop stage.

Coverage is important for weed control, as Pycus is a contact herbicide. A water rate of 200 to 300 L per ha is best for optimal results. Pycus has been shown to be compatible with grassweed herbicides and selected insecticides. Before considering a tank mix, seek advice from your PGG Wrightson Technical Field Representative.

Removing competing weeds from your brassica crop also has benefits for follow-on crops, as it reduces the weed seed burden, playing a crucial role in pasture renovation. Clover will be safe to plant six months after an application of Pycus. Some follow-on crops require a period of at least 12 months before planting after Pycus including fodder beet and lucerne.

To understand the suitability of using Pycus Encaps® and Ombre® within your crop protection programme, contact your local PGG Wrightson Technical Field Representative.


  • Pycus Encaps can be used after an application of Ombre, especially if there are weeds that have escaped control due to dry conditions or a rough seedbed.
  • Use Pycus Encaps ideally three to four weeks after planting, though it is safe at any crop stage.
  • To minimise the crop effects of Pycus Encaps, avoid spraying in the evening, or at times when the products take longer to dry.
  • Pycus Encaps is less effective in controlling larger weeds in dry growing conditions. Wireweed, speedwell, and chickweed are also not well controlled. Use the high rate for larger weeds and those listed as moderately susceptible in Table 1.

Table 1: Levels of control achieved with the use of Pycus Encaps

Weed size  2 to 4 leaf  6 to 8 leaf
Pycus Encaps rate 1.3 L/Ha 1.3 L/Ha
Fathen S S
Nightshade  S
Annual Nettle 
Dock Seedlings MS
Redroot Amaranthus MS


Spurrey (Yarr)  MS MS
Willow Weed MS MS
Californian Thistle MS MS
Dock Regrowth  MS MR
Yarrow MS MR
Twin Cress  MS MR
Shepherds Purse MR MR
Hedge Mustard MR MR

S – susceptible; MS - moderately susceptible; MR – moderately resistant.

Registered pursuant to ACVM Act 1997, Pycus Encaps® #P007774 and Ombre® #P009209. Always read the registered label before use.