Parsley Piert (Aphanes inexspectata)
Parsley piert is a small, low-growing annual weed commonly found throughout New Zealand, particularly in lawns and fine turf. Its tiny size allows it to survive extremely low mowing heights, making it a persistent nuisance on bowling greens, golf courses, and close-mown domestic lawns.
This weed often goes unnoticed until after spraying, as it’s highly tolerant of many selective turf herbicides and can remain healthy when other weeds have been eliminated. Parsley piert usually establishes in autumn, flowers in spring, and dies off in early summer, though it can persist year-round in mild conditions.
While primarily a turf weed, it also occurs in thin pastures and newly sown areas, especially following grass grub damage or poor establishment.
Identification
Parsley piert is a tiny plant with small, lobed leaves that look like a miniature buttercup leaf. Each leaf is about 4–8 mm long and 4–10 mm wide, composed of three leaflets, each divided into several fine segments. The leaves are attached to short stalks on stems that creep close to the soil surface, forming small mats in the lawn.
The stems branch near the base, allowing the plant to spread outwards. Flowers and fruits are minute and inconspicuous, so identification relies mainly on leaf shape.
In lawns, parsley piert can be mistaken for Onehunga weed or other small-leaved species, but a closer look shows the distinctively divided leaflets that make it easy to tell apart once recognised.
Why It’s a Problem
Parsley piert forms small, compact mats that can affect ball roll on fine turf and spoil the appearance of close-mown lawns. Its ability to tolerate most common broadleaf herbicides allows it to persist even in well-maintained turf.
It germinates readily in open patches and thin turf, particularly in autumn, and once established, it competes for moisture and nutrients. Because it grows so flat, mowing offers little control.
Management and Prevention
Cultural control methods:
- Maintain dense turf: Thick, vigorous grass growth shades out parsley piert seedlings and prevents re-establishment.
- Avoid over-thinning turf during renovations: Damaged or scalped patches provide ideal conditions for new seedlings.
- Improve drainage and aeration: Parsley piert favours damp, compacted soil where grass struggles to recover.
- Encourage healthy recovery: Apply balanced fertiliser after weed removal to promote grass regrowth and close gaps.
Chemical Control
Parsley piert is resistant to many common herbicides used in lawns, including MCPA, 2,4-D, dicamba, triclopyr, clopyralid, and mecoprop when used alone. However, a few products have proven effective in trials.
Effective options include:
- Ioxynil + bromoxynil + mecoprop mixtures (such as Image)
- Triclopyr + picloram mixtures (NZLA Gold)
Apply during active growth in autumn or spring, and take care not to damage surrounding fine turf, as both herbicide combinations can stress desirable grass. After treatment, ensure quick turf recovery to prevent reinfestation from fresh seedlings.