Pas­ture weed watch

Get on the couch

NZ Lifestyle Block - - Contents -

AS MUCH as I en­joy my vege gar­den, I have to ad­mit I’m not very good at gar­den­ing. I grow amaz­ing veg­eta­bles, but I have a habit of stuff­ing it up. Like the time I brought clu­b­root fun­gus in on my gum­boots and ru­ined my gar­den for all bras­si­cas. Or the time I ap­plied some fo­liar fer­tiliser and ac­ci­den­tally used my her­bi­cide spray tank. Not pretty.

One of my worst mis­takes was the time I ac­ci­den­tally in­tro­duced a par­tic­u­larly nasty weed to my pris­tine gar­den. I sourced some free top­soil from a farmer client and sub­se­quently spread couch through all my plots. It has been years and I’m still pay­ing the price on that one.

Couch ( Elyt­ri­gia repens) is pro­nounced ‘cooch’ and is a nasty lit­tle grass weed found nearly all over New Zealand. It’s tricky to work out where ex­actly it’s from be­cause it has ef­fec­tively spread all over the world but it’s prob­a­bly na­tive to Europe and Asia. It’s a mem­ber of the grass fam­ily and closely re­lated to wheat­grass, for those of you un­lucky enough to have had a health food smoothie.

Now is a good time to point out that some of you will be scratch­ing your heads and say­ing “that’s twitch, not couch” and you’d be right… sort of. It de­pends on where you come from. I’ve only ever known it as couch so that is ob­vi­ously the right an­swer!

Some of you might be say­ing that couch isn’t a weed, and tech­ni­cally you are right. In some parts of NZ it is used as an an­i­mal feed (as it grows when noth­ing else does) and it does make a nice lawn grass. How­ever put it in a crop, or a gar­den or a good per­form­ing grass pad­dock and you have your­self a nasty lit­tle weed.

As with all grass weeds, iden­ti­fi­ca­tion can be re­ally tricky. Thank­fully there are some lit­tle clues to help with the iden­ti­fi­ca­tion. Couch nor­mally strikes in the spring but can get go­ing nearly all year round. What sets it apart from most other grasses is that it comes away from a rhi­zome, an un­der­ground stem. This is what makes couch an ef­fec­tive coloniser and also makes it tricky to con­trol. Stems pop off the rhi­zome and quickly es­tab­lish them­selves as tufted grass plants. These sub­se­quently flower and produce a seed head al­most iden­ti­cal to rye­grass and very dif­fer­ent from all other grass species.

How to con­trol it

This is the very mean­ing of fu­til­ity. If you try and pull it you had bet­ter make sure you’ve got ev­ery sin­gle last piece of rhi­zome or it will re­gen­er­ate the plant. To make mat­ters worse, those rhi­zomes have a habit of hid­ing in amongst the roots of other plants. If you try and mulch it, you will break the rhi­zome into many lit­tle pieces and each one can be­come a vi­able plant. The fi­nal op­tion is spray­ing. You can let the plants get a bit of size and use glyphosate. This is quite ef­fec­tive but non-se­lec­tive. In crops you can use se­lec­tive grass killer her­bi­cides and in pas­ture you can’t use any­thing. The only ad­vice I can give is main­tain a healthy pas­ture sward and don’t let couch into your pad­dock. Be vig­i­lant if some­one is bring­ing agri­cul­tural ma­chin­ery onto your prop­erty, don’t bring in top­soil un­less you are cer­tain of the source, and you may find it in­vades if you bring in gravel for drive­ways too.

Newspapers in English

Newspapers from New Zealand

© PressReader. All rights reserved.