Sorghum halepense

Johnson grass

Family: Poaceae

Origin: Africa, Eurasia

Johnson Grass in seed in front of wire mesh fence.

Perennial grass from the sorghum family. Rhizomes form underground making dense infestations.

Photo credit: Barry A. Rice, The Nature Conservancy Wildland Invasive Species Team

Regional Pest Management Plan (RPMP) status

Unwanted organism
Notifiable organism

View more about the RPMP statuses

General description

Tufted perennial grass < 3 m tall. Rhizomes are fleshy and creeping. Leaves are smooth, flat and alternate, with pale, prominent midribs and ribbed leaf sheaths. Flowers are borne in large, hairy, purplish pyramidal flowerheads < 50 cm long.

What you need to know

To help protect our environment, you must not breed, distribute, release or sell Johnson grass. As Johnson grass is an Unwanted Organism, these restrictions apply within the Auckland region and across the whole of New Zealand.

If you see Johnson grass anywhere, you must report it to the Ministry for Primary Industries on 0800 80 99 66.

Habitats

Open areas, forest and riparian margins, pasture, crop land, wasteland, roadsides.

Dispersal

Seeds dispersed by wind, water and attachment to animal pelts. Vegetative spread from rhizomes. Human-mediated dispersal through movement of contaminated soil, crop seed, fodder, vehicles and machinery.

Impact on environment

Forms dense infestations, smothering native vegetation and crops. Allelopathic and may be poisonous to livestock.

Control

Recommended approaches

Do not attempt to undertake control of this species. The Ministry of Primary Industries will carry out the control of this species.

Caution: When using any herbicide or pesticide please read the label thoroughly to ensure that all instructions and safety requirements are followed.

Johnson Grass growing in nursery compound.

Seeds are dispersed by wind but plants also spread by rhizomes. Humans can spread plants through agricultural activities.