AGRICULTURAL NEWS - The cotoneasters have been on the 'weeds' watch for a long time.
Their invasive tendencies are evidenced across the globe and reclassification to Cat.1b (must be controlled) of all the species listed below makes good sense.
This amendment aligns with legislation in several other countries where the plants have become naturalised. In regions where climatic conditions are favourable many escapees from cultivation have become invasive weeds, such as the many Chinese species naturalised in northwestern Europe.
C.glaucophyllus is a declared invasive weed in Australia and California and C.simonsii is listed on the New Zealand National Pest Plant Accord, preventing its sale and distribution.
Popular garden shrubs, easily grown from seeds and cuttings, cotoneasters are grown for their attractive arching growth habit and exceptionally decorative fruit. Cotoneaster is a genus of woody plants in the rose family (Rosaceae), native to the temperate regions of Asia, Europe and North Africa.
The highest diversity in the genus is concentrated in the mountains of southwestern China and the Himalayas. Exceptionally species-rich, the plants are mostly shrubs from .5 to 5,0m in height varying from prostrate, low-growing to upright.
Long arching shoots produce the structural branch growth and flowers are born on short shoots. The leaves are arranged alternately, 0,5 to 15cm long, oval or lance-shaped with entire margins. There are evergreen and deciduous species.
Flowering time is late spring through early summer. The small flowers may be single or in clusters, with colour variances from white, creamy-white, light to dark pink to almost red.
The fruit is a small pome (similar to an apple) 5 to 12mm in diameter, pink, bright red, orange or even maroon or black when mature, usually containing one to three seeds. The red berries are highly attractive to birds who act as very effective seed dispersers.
C.salicifolius – (willow-leaved cotoneaster) is a drought-tolerant, evergreen to semi-evergreen, low-growing, small to medium sized shrub with an arched branching habit.
- C.pannosus – (silverleaf cotoneaster, silwer dwergmispel) - native to China - introduced across the world, including Southern Africa and Australia as an ornamental. It is a troublesome noxious weed in Hawaii. This sprawling shrub reaches over 3m in height. It has dull green oval-shaped leaves with fuzzy white undersides and bears white flowers.
- C.franchetii - (Franchet's cotoneaster, oranje/orange cotoneaster) - a semi/evergreen shrub growing to 3m tall. The leaves are oval, (2 to 3,5cm x 1 to 1,5cm) broad, shiny green above, with dense whitish to yellowish hairs below. The tiny five-petal flowers - pink outside, white inside - are produced in clusters of five to 15. The fruit is a red 6 to 9mm diameter pome.
- C.glaucophyllus – (bloudwergmispel, late cotoneaster) - an upright or arching shrub 3 to 5m tall with many branching stems. Young branches are reddish-brown with fine hairs. It is a significant environmental weed that forms thickets under tall trees, and dense infestations will shade the indigenous ground flora and impede regeneration.
- C.simonsii – (Himalayan cotoneaster) - has smallish leaves (± 25 x 15mm) with shiny upper surfaces with a sparse covering of hairs. White to pale pink flowers have five petals (2 to 3mm long) and are is borne in small clusters of one to four flowers. Fruit/seeds: Small shiny, egg-shaped 'berries' (5 to 10mm long) turn orange-red or scarlet when mature. This invasive is a serious problem in the Western Cape.
No herbicides are registered and hand-pulling is recommended. Spotting the seedlings or saplings of invasive species in our gardens makes manual control a simple and inexpensive operation.
