First published in 1995 with a revised edition in 2001, Problem Plants and Alien Weeds of South Africa was in great demand by a variety of organisations and individuals involved with agriculture, plants and the environment. It served as a guide for those who wanted to be able to recognise, understand and control troublesome plants. Many more weedy species than those listed by the CARA regulations were described in the first edition. This third edition is an expanded version of the original books, including particularly those plants that threaten South Africa's indigenous biodiversity.
Clive Bromilow holds a degree in applied biology with a major in ecology. He has been involved in the agricultural chemical industry for over 30 years and this has led to his life-long interest in plants, and particularly weeds.
The book covers more than 500 species of problem plants, with descriptive text highlighting the origin and environmental impacts of each species, as well as methods of control. Melia azedarach (Syringa), for example, is listed under the proposed regulations as Category 1b in KZN, Mpumalanga, Limpopo, Eastern Cape, Norhtwest and Gauteng.
Category 1b means that in these areas the trees are a widespread invasive species to be controlled by a management programme. The Syringa remains in Category 3 in the other provinces, meaning that the trees can be retained on a property but may not be planted or sold. Bromilow gives detailed recommendation on how to control the trees, describing their inclination to coppice strongly when cut back and the need for follow-up treatments. The Syringa is one of the most widespread of all alien invaders in SA an it replaces indigenous vegetation along streams and blocks waterways.
There are over 700 colour photographs in the book to assist identification and illustrate the problematic nature of the plants, Distribution maps show the approximate range of each plant, while a series of icons offers an easy overview of the plant's pest status and how it is covered by both existing and proposed government regulations - and herbicides that are registered for the plant and biological control agents that have been released in the country.
Introductory chapters explain why certain vegetation is undesirable - such as in the case of bush encroachment and recommendations for its control and reversal are given. Biological control and its efficacy is described, relating, for example, how Sesbania punicea (Red Sesbania) is now under effective control owing to the depredations of three insect species. There are also sections on chemical weed control and herbicide resistance. The threat of introduced ornamental and crop plants is discussed in another introductory section.
At the start of the introductory chapters, Bromilow explains that "a weed is a plant in the wrong place at the wrong time". Any plant can be a weed... but those that become weeds are usually vigorous growers that compete for water, light, space and nutrients...they are adaptable, invading a wide range of ecological niches and tough, and most of them are exotic (alien) in origin. They spread easily... and "the most frustrating characteristic is that, for a number of reasons, they are difficult to control." A quick "elimination key" provides an easy way to fid a plant in the book.
The book carries the List of Declared Weeds and Invader Plants which is presently in use under the Conservation of Agricultural Resources Act (CARA) and an additional column which covers the proposed National Environmental Management Biodiversity Act (NEMBA) categories.