Pasture Weed Watch
Paspalum
Why is it a weed?
Invasive in pastures and lawns, spreads quickly in summer when ryegrass growth slows. Colonises pasture areas, reducing quality and quantity.
Where is it found?
Common in North Island but found as far south as Canterbury.
Is it toxic?
Seedheads can contain an ergot-type fungus that, when eaten, can cause staggers in cattle, sheep, and horses.
Other uses
Provides green feed in hot dry summers.
THE BARE PATCHES of soil in my older pasture paddocks are greening up, but not with the pasture plants I want.
Instead, it's paspalum (Paspalum dilatatum and Paspalum distichum), a 'C4' type of grass, like maize, sorghum, and millet. 'C4' means it grows well in hot, dry conditions, and out-competes ryegrass during summer. In winter, the paspalum dies off, leaving bare areas.
Paspalum is easy to spot:
• it's usually the largest leaved grass in pasture;
• it tends to grow in clumps quite flat to the ground;
• from summer to autumn, it puts up a sturdy stem and seedhead that is difficult to mow off;
• leaves often have a purple colour along the leaf margin and at the base of the leaf blade where it joins the stem;
• has 4-7 finger-like seedheads that can feel sticky to the touch.
How to control it
The best way to control paspalum is to top it regularly to prevent seeds forming, remove plants by hand, or spray them using a non-selective herbicide such as glyphosate. Reseed with ryegrass or other pasture plants.