Californian Thistles

The total effect of effective pasture loss with Calis has been reported as 600kg/Ha in a low density thistle paddock! The Californian thistle is without doubt the most economically significant of New Zealand’s pasture weed species.

Californian Thistle weed file (rainbowbrown.co.nz)

I’ve heard farmers call them Calis. In their company, I’d slip into the lingo easily enough: “Great crop of Calis you’ve got there.” When June and I talk about our crop, it’s the long-winded sounding and long stemmed growing Californian thistle.

In my imaginings, you can take a more relaxed approach to a weed called Cali, like you can with an old acquaintance you’ve always called by his nickname.

It was a Southland farmer that first brought to the attention of researchers the observation that his Calis got knocked back more if he mowed them in the rain. In field trials:

… results showed that mowing when wet improved the control of Californian thistles by approximately 30% compared to dry mowing. … It is likely that mowing when wet spreads helpful diseases like vascular wilt (yellowing and wilting) and Californian thistle rust (orange/brown spores on the underside of leaves during late spring/summer).

californian-thistle-control-mowing-wet (beeflambnz.com)

Being a no spray man, that was good enough for me. I’ll scythe them when it’s dry if my ’roundtoit’ and a summer drought dictates, otherwise I’ll don my rain jacket, sharpen my scythe, and do some reaping of the non-grim kind. Don’t have to bother about the goats’ five acres though – they take care of that!

You want to get them before the miniscule seeds, made airborne on feathery parachutes, are taken on a puff of wind to colonise patches of bare earth; when the energy of the thistles is being used up pushing sugars to feed stems, flowers and developing seeds. You don’t want them recouping their energies and, job done above ground, feeding more sugars back down to feed those creeping root systems.

A big part of the problem is that, unlike all other thistles in New Zealand, they’re perennials: Instead of dying off after the growing season, they stay alive underground during winter and come up again the following spring.

They’re a problem sure enough, but as I said, it’s not a grim exercise: I enjoy it once I get out there and into a rhythm; Californian thistles and a good scythe are made for each other. By the time I get to them they have straight stems anywhere between half and one and a half metres in length; grass stalks suppressed by the thistles, the blade doesn’t snag and all in the path of a single sweep topple as one.

Topple as one also because a big patch may well be (or once was), a single plant! It’s so difficult to control because its creepy root is still alive through winter and new tops pop up the following spring. “Very troublesome” in a Massey University research paper is followed in earnest by:

Once a plant has established in pasture, it forms a patch of plants which are initially connected by the creeping root system, but these connections rot away in time. These patches of thistles eventually get larger over time if conditions are suitable for its growth.

Californian Thistle – Massey University

It’s starting to drizzle – better get out there and scythe this year’s crop. Not as an old white man going on about “very troublesome” Californian thistles the way you might go on about “the trouble with the youth of today”, but as an old white man kidding himself that he’s in control of his home patch.

That’s all on modern-day homesteading at Little Owl Gully till next Monday. Thanks for your company. Bye for now.