What does it look like?
Broom is an upright, many-branched, almost leafless woody shrub, reaching up to 3m tall. It is a perennial plant with a stout taproot. Leaves are sparse, mostly narrow and simple. It has golden-yellow flowers in spring that are 2.5cm long and produces seed pods in summer which are black when ripe and explode loudly on warm days, scattering the seed.
Broom grows in riverbeds, hedgerows, low-fertility hill country, scrubland, coastal and disturbed land. It’s tolerant of a wide range of conditions including drought and frost but requires good drainage.
Why is it a problem?
Broom is an aggressive and invasive shrub that seeds prolifically, with each pod producing nine seeds and usually more than 2000 pods/bush. These seeds can still be viable after five years.
This means that not only will broom displace native species which would normally grow there, it also makes control difficult as it needs to be managed regularly (seedlings pulled out) while trying to establish native bush.
Control methods
Physical control
Firstly, establish that the plant is not native broom. Control only where broom is a recent threat, of low incidence or poses a high ecological threat. It resprouts after slashing. Pull or dig small plants (all year round). Ensure minimum soil disturbance. Leave on site to rot down.
Herbicide control
Stump swab (all year round) with Triclopyr 600 EC (50ml/L) or triclopyr 120g/L (250ml/L) or metsulfuron-methyl 600g/kg (5g/L). Or
Spray (spring-summer) with Metsulfuron-methyl 600g/kg (7.5g/15L + penetrant (knapsack) or 35g/100L + penetrant (spraygun)) or a product containing 100g picloram+300g triclopyr/L (90ml/15L (knapsack) or 200-300ml/100L + penetrant (spray gun).
CAUTION: When using any herbicide or pesticide, PLEASE READ THE LABEL THOROUGHLY to ensure that all instructions and safety requirements are followed.
Multiple biological controls have been released in New Zealand with varying degrees of success. These include the broom gall mite, broom leaf beetle, broom psyllid, broom seed beetle, and broom shoot moth.
Related links
https://www.landcareresearch.co.nz/discover-our-research/biodiversity-biosecurity/weed-biocontrol/
http://www.nzpcn.org.nz/flora_details.aspx?ID=3839
https://www.weedbusters.org.nz/what-are-weeds/weed-list/broom
http://www.nzflora.info/factsheet/Taxon/Cytisus-scoparius.html
Management Programme
Organism of Interest (OOI)
Organisms of Interest are those specified as pests under our Regional Pest Management Plan that are capable of causing significant adverse effects on one or several of our Regional values. These species warrant being watch-listed for ongoing surveillance or future control opportunities.
