|Weeds in our Area (Part Eighty Nine)
By Bob and Ena McIntyre – Garden Route
Chinese and Pink tamarisks
(Tamarix chinensis and T. ramosissima)
Of the many Tamarisk species introduced into South Africa two have become problem plants; mainly in the central southern regions of the country and have been declared Category One Weeds in the Western, Eastern and Northern Cape. In the rest of South Africa they are Category Three. Tamarix as a species occurs widely across Eastern Europe to Central and Eastern Asia. There is even an indigenous species T. usneoides.
The graceful feathery appearance of the Tamarisk made the various species popular garden subjects and as long ago as the 1950’s T. aphylla was known to grow “wild” in the Karoo and Namaqualand. Generally recommended for both coast and inland and particularly suited to “difficult” gardening conditions as an ornamental, Tamarisks were also used for shade, erosion control and as a honey source. The two species that have become problematic invade mainly sandy riverbeds in the Karoo and the western half of the Eastern Cape, impacting on water resources.
Identification: The two invader tamarisk species Tamarix chinensis and T. ramosissima are evergreen shrubs or small trees 3 to 6 meters tall. The bark on T. ramosissima is reddish-brown and that on T. chinensis is black or dark brown. The leaves on both species are minute scale-like, deep green, grey or blue-green in colour. The flowers are pale to purplish-pink in racemes between 15-70 mm long, at the ends of long thin twigs. The fruits are papery capsules 3-4mm long. (NB the indigenous species T. usneoides has overlapping pale green-grey leaves and whitish flowers on terminal twigs.)
Control: A cocktail of imazapyr (Arsenal) and glyphosate (Round-up or Mamba or equilivant) mixed with water. Imiboost is registered as an aerial herbicide application. The best solution for small infestations is to physically remove and destroy.
Indigenous Substitutes: Polygala myrtifolia (Septemberbossie), Polygala virgata (Purple broom), Dodonaea angustfolia (Sand Olive), Clerodendrum glabrum (Cat’s whiskers)
References: “ALIEN WEEDS AND INVASIVE PLANTS”; Lesley Henderson. Copyright © 2001 Agricultural Research Council, Ornamental Shrubs and Trees for Gardens in SA; Una v/d Spuy