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Weeds in our Area (Part Seventy) By Bob and Ena McIntyre – Garden Route Branch Pinus radiata Pinus radiata (radiata pine, Monterey Pine) is another of the ‘pine’ species that are problems in the Southern Cape. This one originates from the south west regions of North America. As with all other pinus species that have become problem plants in South Africa the radiata pine was introduced for commercial purposes. “Escapees” from formal plantations found hospitable and enemy free surrounds in areas of natural indigenous vegetation and soon established themselves. Pinus radiata was also recommended as a fairly fast growing, large garden subject well-suited to the Western Cape and the Knysna areas. Interestingly its attraction as garden subject lay in the shape (see picture and identification below) - the impressive tall rounded shape making it a striking solitary specimen in a large garden. Most pinus species seed germinate easily when conditions are favourable. Their invasive status is that of transformer, and they significantly increase fire risk. Fynbos, forest gaps, grasslands areas - usually on moist mountain slopes, are the most affected. Due to the commercial value of the timber production all pinus species have been classified category two. These are allowed in controlled zones such as registered plantations but our natural areas should be kept free of these plants. Identification: Radiata pines are coniferous trees 12 to 25 meters tall occasionally reaching up to 30 meters with a sharply conical canopy in plantations but a broad rounded canopy when grown in open areas. The dark green leaves (needles), in bundles of two or usually three needles are very densely arranged and 60-150 mm long. The bark is deeply furrowed and the cones are yellowishbrown, woody, 70-140 mm long and persistent (long-lasting on the plant and do not drop easily). Control: P. radiata (radiata pine) like other pines does not usually coppice and may be felled or ring-barked without applying a herbicide. Seedlings and young plants may be hand-pulled when the soil is damp. No herbicide is registered for this species. The laws regulating the use of herbicides prohibit the use of herbicides registered for a particular plant species on another species. This means that herbicides registered for Cluster Pine preclude their use on other pine species regardless of whether they may work. Follow-up is an essential ingredient with all eradication programs,. References: “ALIEN WEEDS AND INVASIVE PLANTS”: Lesley Henderson. Copyright © 2001 Agricultural Research Council. Problem Plants of SA by Clive Bromilow. Ornamental Shrubs and Trees by Una v.d. Spuy, The A-Z of Gardening in SA by W.G. Sheat Substitutes: Podocarpus spp (Yellowwood), Widdringtonia spp (Cypress family)