Paspalum

How to Kill Paspalum in NZ Lawns and Pasture

Botanical name: Paspalum dilatatum  |  Also known as: Dallis grass, common paspalum

Quick answer:

Paspalum is a coarse, clumping, warm-season grass that is hard to control because anything that kills it also kills the grass around it. In a lawn, the practical fix is to spot spray with glyphosate in late summer to early autumn, rake out the dead patch and resow. In pasture you either spray out and resow, or spot spray.

• Spot it by its wide, flat leaves and a seed head with only 4 to 7 fingers.
• It spreads by short, stout rhizomes that knit plants into dense clumps, so digging only partly works.
• Use the low rate at early seed head and the higher rate on mature plants, before the first frosts.
• Seed heads can carry a fungus that causes staggers in cattle and horses, mainly in autumn.

Paspalum is one of the most common lawn grass weeds in the North Island, and it is creeping south. It is just as much a problem for lifestyle block owners and farmers, where it competes with ryegrass over summer. Because it is a grass, there is no easy fix, so the trick is getting the timing and the rate right.

What is Paspalum?

Paspalum is a large, coarse, low-growing perennial grass with short, stout rhizomes that join individual plants into dense clumps. In a lawn it is usually easy to spot because it has about the broadest leaves of any lawn grass, grows flat to the ground and has tough leaf-stems that are hard to mow cleanly.

Look at the base of the leaf: the ligule has a tuft of hairs on either side, and the leaf otherwise has few hairs. The leaf edge can have a slight purple tinge. The seed head is the easy giveaway, with only 4 to 7 "fingers" (Vasey grass has far more). Paspalum needs warmth to thrive, so it grows hardest over summer and is much less active over winter. There are three species you may meet: common paspalum (Paspalum dilatatum), Vasey grass (Paspalum urvillei, tall and usually roadside) and Mercer grass (Paspalum distichum, usually in swampy ground).

Where Does Paspalum Grow in NZ?

Paspalum is mainly a North Island problem because it needs warm conditions, though it is now spreading south.

• Traditionally found in lawns and the flower gardens beside them.
• Thrives in waste areas, roadsides and orchards, as well as pasture.
• In pasture it gives some summer feed, especially in dry summers, but it competes with perennial ryegrass over summer, so there is less quality ryegrass for winter feed.
• Vasey grass is mostly roadside and Mercer grass is mostly in swampy areas.

Does Paspalum Harm Livestock?

How Do I Remove Paspalum Manually?

Digging out paspalum is only partly effective. The rhizomes are brittle and snap when you dig, so regrowth from the pieces left behind is likely. Mowing does not kill it either, and the tough stems tend to escape reel mowers. Hand removal makes sense for a few young plants or as a follow-up after spraying, and rake out all the dead rhizome material afterwards.

What Products Control Paspalum?

Glyphosate is the main tool. In pasture, spray out the whole paddock or spot spray in late summer, then resow. The same applies to lawns, although most people would spot spray the lawns, rake and re-sow.

Use the lower rate when plants are at early seed head, and the higher rate on mature plants before the onset of frosts. Glyphosate kills all grass and most clover, so expect dead patches and plan to resow in autumn.

Spot spraying (small areas and lawns)

Boom spraying (pasture and large areas)

Spraying out the whole paddock, then resowing ryegrass and clover in early autumn.

Orchards and non-crop areas

Cut stem / wipe treatment

Just a smear on the ends is all you need. Apply the gel straight after cutting, and support the paspalum with a gloved hand while you apply it. Glyphosate gels also kill any grass they touch.

Common Mistakes

Quick Checklist

• Spot the paspalum by its wide flat leaves and 4 to 7 finger seed head.
• Mix G‑360 Glyphosate or G‑540 Glyphosate or Granny Herbicide at the rate for your sprayer.
• Spot spray in late summer to early autumn, low rate at early seed head, higher rate on mature plants.
• Wait a few weeks, then rake out the dead material and rhizomes.
• Resow bare patches in autumn.

Next step: Choose your glyphosate: G‑540 Glyphosate is the concentrated option, and G‑360 Glyphosate is the standard one.

FAQs

Can I kill paspalum without killing my lawn?

Not completely. Paspalum is a grass, so anything that kills it also damages the grass it touches. Spot spraying keeps the damage to the patch, and you then rake and resow.

When is the best time to spray paspalum?

Late summer to early autumn, while it is actively growing. Use the low rate at early seed head and the higher rate on mature plants before the first frosts.

Does glyphosate kill paspalum?

Yes. G-360 Glyphosate and Granny Herbicide list paspalum on their labels, and G-540 Glyphosate is the same active in a more concentrated form. They are non-selective, so they also kill any other grass and most clover they touch.

Is paspalum poisonous to horses or cattle?

The grass itself is feed, but the seed heads can carry a fungus that causes staggers, mainly in cattle and horses in autumn. Topping seed heads and moving stock to clean feed helps.

Further Reading

• Kikuyu - another warm-season lawn and pasture grass that glyphosate controls
• Yellow Bristle Grass - a summer grass weed with the same non-selective approach
• Pampas Grass - a larger grass weed, controlled the same way
• Pennyroyal - a common lawn weed you may find alongside paspalum