Abstract

In recent years, there has been a revival of interest in the use of hemp as a fibre and medicinal crop. Unfortunately, information regarding management of the numerous pests and diseases that attack this crop is hard to find as most of it is in either obscure agronomy journals more than 50 years old or semi-clandestine ‘grey journals’ dealing with the cultivation of illegal Cannabis. Control recommendations are years out of date, as most hemp research occurred when DDT was still commonly used. In this book, the information has been updated and collated into an accessible, well presented volume that will be an excellent reference for growers and researchers in the hemp industry.

The book is divided into three sections. Section One: Prerequisite Information about Crop Biology has three introductory chapters dealing in turn with the principles of integrated pest management, agronomic requirements of hemp, and some explanation of the concepts of taxonomy and ecology. These chapters are easy to read with many interesting little anecdotes, and very informative with clear definitions of terms and good use of diagrams and keys. A small criticism is that when discussing IPM, the authors tend to be over-enthusiastic in their promotion of organic and bio-dynamic farming methods and slightly ‘conspiracy-theorist’ about chemical companies and the USDA!

Section Two contains five chapters specifically addressing diseases and pests of Cannabis, including abiotic diseases and post-harvest problems. These chapters provide a very comprehensive coverage of the pests and diseases, closely following the format of APS Compendium books, with good descriptions of symptoms and their causal organisms, ample drawings, photographs and micrographs, and information on disease cycles, epidemiology and control measures. The chapter on abiotic diseases covers nutritional disorders, herbicide damage, climatic hazards and genetic disorders, and the chapter on post-harvest problems deals with fibre rots, seed deterioration and storage moulds. All of the information provided is well supported by references, with an extensive bibliography (24 pp.) at the back of the book. There are also several pages of excellent colour plates.

Section Three comprises three short chapters covering general control measures. The emphasis is strongly on cultural, mechanical and biological controls, with chemical control mainly limited to those pesticides considered to be compatible with organic farming methods. Additional information on synthetic chemicals is provided in an appendix at the back of the book. The authors acknowledge that biological and chemical control information changes rapidly and suggest the reader also access alternative sources of information such as websites and annual directories. The chemical control chapter includes information on pesticide regulations in the USA, safe handling procedures and a brief description of pesticide application methods.

At the end of the book are three appendices, the reference list and an index. The first appendix, as already mentioned, gives a brief synopsis of different pesticides groups and lists a number of examples of synthetic pesticides. Once again, the reader has to allow for the authors bias against these chemicals. The second appendix comprises a dichotomous key of diseases and pests, which categorises symptoms by plant part such as seeds and seedlings, lower stalk, leaves and so on, enabling the user to identify the problem (in most cases) simply and quickly. A third appendix lists conversion factors between English and Metric measures. Lastly, the Index appears to be comprehensive and accurate. Overall, this publication is comprehensive, well presented and potentially very useful if the hemp industry does succeed in being resurrected.

J. Edwards

Institute for Horticultural Development, Knoxfield, Victoria