Pasture Watch

The most toxic weed on your block

Why is it a weed?

Competes with desirable species

Where is it found?

Nationwide, common in gardens and pastures

Is it toxic?

Yes, even when dead and dried, but livestock tend to avoid it due to its strong smell

MOST BLOCK owners are aware of toxic ragwort, but far fewer know how to identify hemlock, despite it being one of NZ's most poisonous plants.

Hemlock (Conium maculatum) is a biennial weed, generally found in isolated patches. However, occasionally it can get out of hand, especially in new pastures where seeds have built up in the soil.

In its second year, it can grow 3.5-4m high, with lots of white flowers. The leaves have a strong, unpleasant, musty, mouse-like odour. However, the smell is often very faint in young plants, so don't rely on smell alone to identify it.

How to control it

Small patches can be hand-pulled – wear gloves to avoid an allergic reaction to its sap.

Sprays such as Tordon™ Pastureboss™ are grass-safe and effective on small hemlock plants but will struggle to kill larger ones.

Seek professional advice before using chemicals, and always read the label.