December Weeds

California Thistles

December is a good time to focus on control of these thistles. The key problem with the California Thistle is the underground network of roots, and moving chemical through this network is vital. A practice used at this time of year is to mow the thistles towards late November early December, with the purpose of obtaining an even growth, and to try and encourage the plant to push out shoots at as many growing points as possible, as the more growth points taking the chemical down into the plant the better. The chemical is then applied at the hardball (flower bud) stage, at about 85% colour. The reason for this is that at this stage the plant is pushing nutrients down into the plant before seeding, providing the ideal opportunity for the chemicals to move through the plant. At this stage, Tropotox applied at the rate of 4lts/ha, ensuring good leaf coverage, is an option, with the benefit derived from being able to apply a clover friendly herbicide in a pasture situation.
Another option at the hardball stage, is Baton. It would be advisable to hard graze the paddock and allow it to freshen up before applying this product in order to limit any clover damage. This has shown good results, and is a cost effective option, however you need to follow the instructions carefully in order to limit any clover damage. Other options include using chemicals such as Versatill/Vivendi or Tordon Max in a weed wiper. If you add Glyphosate to the mix, you will have to be careful to avoid the grass, as the Glyphosate will kill the grass. Ensure that the plants are showing a vigorous growth at the time, and that they are not stressed or wilted. Remember, control of California Thistles is a process, and follow up sprays will be required. A further spray should be applied in March to kill the newly-emerged shoots. Repeat the process until satisfactory control is achieved. In a cropping situation such as fodder brassica crops, where a combination of Radiate and Versatill/Vivendi may be used, the ideal situation presents itself to hit this weed hard, and the best should be made of this opportunity.

New Pastures

A number of new pastures are being sprayed for control of young nodding thistles and other broadleaf weeds, and there are some factors which need to be considered. Controlling the thistles in the seedling stage allows the use of clover friendly herbicides, so the opportunity should not be missed. There are a number of other weeds which grow prolifically and can choke out young pasture, and should be controlled along with the thistles. Below are some of the problem weeds which I encounter regularly in young pasture.

Spurrey, Shepherd’s Purse, Chickweed

These three weeds are inclined to grow prolifically, and choke out the new grass and clovers, slowing their growth considerably. They are not controlled by Tropotox or MCPB by themselves, they need the addition of Preside plus Uptake Oil, which works particularly well on these three weeds, or Pulsar, helps to control them, and to broaden the general spectrum of weed control.

Nettles

Nettles can totally choke out a new pasture. In order to control this weed, the options are Pulsar or Baton. Baton has a recommendation for application at 1.5kgs/ha on white clover, or 1kg/ha on red clover, to be applied 3-5 days after the first full grazing, when most of the clover leaf area has been grazed off. Weed control in young pasture extends beyond just thistles, other weeds can seriously hinder pasture establishment. Recommendations would vary according to the weed spectrum.

Steve Lawson is the ATS Field Rep. Please contact him for any further information or assistance, or if you would like an on farm visit. He may be contacted by mobile:
027 24 55 661, or via ATS during working hours. Or e-mail steve@ats.co.nz