Besom Heath (Erica scoparia)

Besom Heath

Family: Ericaceae

Growth Habit: Erect multi-stemmed shrub with dense foliage and large, thick underground lignotuber. Small, fine leaves 3.5 – 7 mm long, in well spaced whorles of 3 (or sometimes 4). Young stems are hairless.

Type of Plant: Perennial evergreen lignotuberous resprouting shrub up to 4 metres, but usually less.

Besem Heath

Flowers: Tiny white/green flowers that turn red-brown with age. Flowers are bell-shaped drooping flowers, 1-2mm long, borne in clusters at the ends of its shoots. Flowers in spring to summer.

Photo: Matthew Baker
Photo: Matthew Baker

Fruit/Seed: Prolific producer of very fine seed, each bush is capable of producing millions of speck like seeds.

Dispersal: Prolific very fine seed easily dispersed on vehicles and machinery, shoes, contaminated soil and road base, plant material, stock, animal fur, clothing and in water. Wind may also disperse seeds.

Differentiated from the similar Heath species:

  • Spanish Heath (E. lusitanica):  Larger flowers 4-5 mm. Leaves long, narrow and generally crowded in whorls of 4. Young stems have unbranched hairs 1mm long. Flowers winter to spring.
  • Tree Heath (E. arborea): Not yet in the Tamar. Tall shrub to 5 metres. Slightly larger white flowers 2-3 mm long. Leaves long, narrow and generally crowded in whorls of 4. Young stems with branched hairs 1 mm long.
  • Berry Heath (E. baccans): Not known to be in the Tamar. Flowers are bright pink (magenta), globular, approx. 5 mm long, in bunches at stem tips. Leaves up to 9 mm long in whorls of 4. Young stems are hairless.

Distribution: Currently only found in Northern Tasmania, primarily within West Tamar around Bridgenorth. The northern Tasmanian besom heath infestation now covers approximately 250 ha with approximately 20 outlier infestations (of less than 20 ha each). Highly likely to spread throughout Tasmania and into Victoria if not contained.

Status: Besom Heath is a declared weed in Tasmania. It has the potential for economic impact as it can invade agricultural land used for grazing. The potential costs of removing it from conservation areas is enormous. It is capable of completely overwhelming the native vegetation. Present roadside management has the potential to significantly spread this weed once it becomes established on roadside areas. Some of the current roadside infestations have come from the use of contaminated soil and road base.

Weed Impact:

  • Deep root system with lignotubers and high capacity to resprout after fire, slashing, grazing and even spraying.
  • Very competitive in nutrient poor soils.
  • Readily invades and takes over grassland and heathland, dominating sites and resulting in a loss of pasture and native species.
  • Easily spread along roadsides and then into neighbouring agricultural and native vegetation areas.
  • Invades grasslands and therefore changes habitat for species requiring grassy systems.
  • Unpalatable to stock.
  • Known to cause serious growth problems in crop plants, particularly grass and clover species due to allelopathic properties.
  • Readily spreads into bare areas after disturbance such as clearing and fire.
  • “Not palatable” – Not eaten by stock, only limited grazing by goats.
  • Highly resistant to fire and water logging, tolerant of drought and may be tolerant to salinity.

Control Methods:

  • Should it appear, rapid early efforts should be made to eradicate it.
  • Implement weed hygiene practices on areas such as roadsides, new trails, walking and cycling tracks, dirt roads, forestry tracks, etc.
  • Wash down all machinery coming from contaminated areas, including slashers, graders, dozers, tractors, etc.
  • When using machinery in infested areas, such as roadside slashing, move from non-infested areas into infested areas, then wash down machinery before moving out again.
  • Raise awareness about weedy Erica species among gardeners, landscapers, nursery suppliers, florists and road management authorities.
  • Hand pulling of seedlings and small plants is possible in moist or light soil. Make sure you get all the basal lignotuber, because if parts of it remain in the soil vigorous regrowth is likely.
  • Grubbing of larger isolated plants may be possible. Make sure you get all the basal lignotuber, because if parts of it remain in the soil vigorous regrowth is likely.
  • Trials are currently underway in the Tamar to determine the most effective chemical control. If the wrong chemical is used, or at too low a dose, leaves may die off but the plant can resprout. Currently Erica species are not listed on any registered herbicide labels in Australia. It is hoped that these trials will provide an off-label permit for the appropriate chemical to be used.
  • Cultivation is successful in agricultural areas.
  • DO NOT use fire as Besom Heath (and other weedy Erica species) readily resprout after fire.
  • In selecting the most suitable control techniques it is essential to minimise adverse impacts on native vegetation and to encourage its subsequent recovery.
  • Whichever methods are used, it is important to manage plant material that may be carrying seeds to prevent dispersal.

NB Always check the herbicide label before use