Plant Science 159 (2000) 313 – 315
Book review
www.elsevier.com/locate/plantsci
Principles of Weed Science (second edition), By V.S. Rao, Science Publishers, Enfield, NE, USA, 2000, 555 pages, paperback only. ISBN 1-57808-069-X; US$ 49.50
The author states that he has endeavored to ‘‘discuss the various advances since the first (1983) edition, with up to date information on newer approaches in weed management’’, etc. A quick perusal of the reference section of a group of chapters, including that on biotechnology, shows that the most recent references are from 1996. Moreover, it is not too clear how much outdated, superceded or incorrect material in the first edition was removed, as much remains. Many recent but classic reference books in weed science have not been cited, so students reading this book, written as a ‘‘text cum-reference book’’ are totally depen-dent on their lecturers to hear about these excel-lent references as resource material.
The book is divided into 19 chapters. The text is clearly written, without convoluted sentences, and with a logical and didactic flow of information. It has a 21-page general subject index, as well as a four-page weed index using Latin names with some common names in the general index. It also contains: a glossary; appendices on acronyms; Latin versus common names of weeds; an out-dated appendix of herbicide names; an appendix of crops ‘‘transgenic with herbicide resistance’’ (where two are actually mutants, and oilseed rape, the first to market and widely grown, is not listed); an appendix on herbicide manufacturer mergers (which daily becomes outdated due to no fault of the author); an appendix on metric versus US conversions; and two appendices replacing calcula-tors for herbicide dilutions.
The introductory chapter adequately defines weeds and the damage done, and the increases in yield that emanate from near-perfect weed control. Unfortunately, the author does not point out that
this 10 – 20% yield loss occurs despite huge outlays for cultivation and chemical weed control.
The long chapter on weed biology veers from simple definitions of the mundane to peculiar statements such that ‘‘most weeds are perennials’’ (based on a 1971 paper on photoperiodicity in
Cyperus), without clarifying if this is by number of species, damage, or prevalence. The short section on genetics is sophomoric and will not be useful to a student, despite the importance of genetics to understanding weeds. Allelopathy receives about the same coverage as genetics. The discussion of dormancy does not include primary and secondary dormancy. Some very important recent books are missing from the citations: Holm et al. (1997) on the biology of specific weeds, Powles and Holtum (1994) on herbicide resistance (a 1981 book on that subject is cited), as well as the excellent text book by Cousens and Mortimer (1995) on weed population dynamics.
An interesting potpourri chapter entitled ‘‘Tra-ditional ecophysiological and other approaches to weed management’’ contains headings about ‘‘cherling’’ and ‘‘sickling’’, words that do not ap-pear in dictionaries — nor in the glossary of this book. The bit on ‘‘ecophysiological approaches’’ describes water and other stresses, but not how they relate to weed management. There is a useful discussion of intercropping and companion crop-ping. The two-page discussion of weed germina-tion stimulants does not say that they have never been made to work effectively in the field.
The following seven chapters deal with chemical aspects of weed control, followed by a short chap-ter on biocontrol, and then chapchap-ters on herbicide interactions, discovery, and application. The in-troductory (mainly terminology) chapter is fol-lowed by one on basic information about the chemicals (as well as bioherbicides and safeners). It has a useful table classifying herbicides by soil versus foliage applied, systemic versus contact
Book re6iew
314
fects. It claims to have omitted ‘‘not widely used or phased out’’ compounds, yet a quick count yields at least nine compounds relegated to the ‘‘superceded or no longer manufactured’’ category in the 1994 Pesticide Manual. The following sec-tion on herbicide structure and use (a mini Herbi-cide Handbook) also contains compounds no longer available. As ‘‘no longer used’’ means that compounds that are more cost effective replaced them, or that they were withdrawn for toxicologi-cal and/or environmental reasons, why waste so much space on them throughout the book? They have as much relevance as copper sulfate and sulfuric acid, used as herbicides in the first half of the century. Rudimentary aspects of synthesis of each compound are given; but their relevance to principles of weed science is not clear to me, but this fills 45 pages.
A short section of the chapter on absorption and translocation is devoted to some fundamentals (based all on the old literature — not updated it seems), and then 13 pages go through absorption and translocation, herbicide by herbicide. Items of practical importance, such as the very negative effects of divalent ions on glyphosate absorption, nor the importance of surfactants to facilitate more than the otherwise 5% uptake are not included.
The chapter on mechanisms of action fails to differentiate between the target sites of the herbi-cides and the often only (seemingly) tenuously related cause of death. Additionally, primary and secondary effects of herbicides on metabolism are not distinguished. A slew of herbicides is classified as having protein or nucleic acid biosyntheses as their target. The author forgets that dead plants have problems in synthesizing these macro-molecules. We are given a few pages on chloroac-etamide effects on polysomes, (from a quarter of a century ago) without saying that this is not a primary effect. Nor are we told that pyridate binds more strongly to photosystem II of triazine-resis-tant weeds than sensitive ones, with importriazine-resis-tant implications to resistant weed management. In-deed there is no discussion on how herbicide resis-tance assisted in elucidating target sites.
The chapter on ‘‘herbicide transformations’’ (i.e. mainly detoxification) again starts with a few pages on the basics and then goes herbicide by herbicide. The data are given in an off-hand man-ner with little effort to put them in a metabolic context, or a weed management context.
The chapter on herbicide persistence again starts with basics and then seemingly randomly provi-dides factoids on particular herbicides. For exam-ple, we are not told that chlorsulfuron cannot be biologically degraded in high pH soils, but re-mains biologically active for years. As this limits crop rotations, it is a relevant factoid. How a chapter on this topic cannot point students to the multiple volumes by Kearney and Kaufman on just this subject is beyond comprehension.
Herbicide resistance in weeds and genetic engi-neering of crops to resistance are lumped in one chapter. The resistance part is sophomoric, and the engineering part way behind the times. ALS-resistant maize is not yet commercialized accord-ing to the author, yet has been on the market for over 5 years. It is doubted that the author read all the references (including a ‘patent application’ of a patent issued long ago) and he has this reviewer as the sole author of a chapter in a book he did not contribute to. He has the same book listed in more than five places with different editorships and publishers. More importantly, the excellent book edited by Duke (1996) on herbicide-resistant crops is not cited.
The chapter on biocontrol is mainly a descrip-tion of the agents used. It does not discuss which weeds are most amenable to this approach, nor does it differentiate between classical biocontrol (using agents imported from the weed’s center of origin) and inundative biocontrol (using local in-digenous agents), or the implications thereof. Re-cent books on the subject (e.g. TeBeest, ed., 1993) are not cited, but articles from the 1960s about agents that never realized success are cited and described as if in use.
The chapter on herbicide interactions (mainly safeners) contains nothing from the last decade and much of the discussion is about compounds off market. It does include some now irrelevant 20 year old polysome data.
The herbicide discovery chapter describes com-pounds discovered by random screening as if they were found biorationally, by virtue of their target of action being discovered after the fact. The current use of genomics for rational discovery does not appear, but there is a sentence on the use of antisense to find new targets.
Book re6iew 315 all spraying in agriculture is performed manually.
It also discusses ‘‘sand-mix’’ application, i.e. hand (ungloved) broadcasting. Hardly advisable from safety considerations, but unfortunately still prac-tical in the developing world.
In the chapter on ‘‘40 prominent weeds and their management’’ seven species do not make Holm et al.’s 1977 and 1997 top 180 species of world’s worst weeds. Parasitic Orobanche and
Strigaare mentioned only in the context of India, yet are far more widespread and devastating
around the Mediterranean and sub-Saharan
Africa respectively.
A series of chapters follows with advice for various cropping systems. This includes advice on how to provide roadside weed control, needed to preclude its being ‘‘good hideouts for thieves, rob-bers and gangsters at night, and thus making travel hazardous’’ (p. 485).
The last 18 pages are dedicated to field research methodology.
Despite being published in the USA, it is clear that the book is pegged towards training of weed scientists in tropical or sub-tropical developing countries. It does not provide students or re-searchers with a current, balanced, up-to-date dis-course, with references to the truly key recent books and papers in weed science. Thus, using such a book as an unaugmented source will be a disservice to students and it does not meet its aims. It is not (in the estimation of this reviewer) the ‘‘very useful reference cum text book’’ includ-ing ‘‘up to date advances’’, as stated on the book jacket.
Jonathan Gressel
Plant Sciences,
Weizmann Institute of Science,
Reho6ot,
Israel
