This book is written largely from an agricultural point of view and stresses both present and possible future important commercial uses of growth substances in agriculture. However, coverage of the field of growth substances is made more complete by inclusion of chapters on their nomenclature and history, chemical and biological determination, occurrence and chemical nature, and biological effects and mechanism of action. Some of the theory explaining the effects of exogenous regulators on plants is interwove throughout the book. A chapter on growth substances in weed control is included since this is still the greates commercial use for growth substances. Spray recommendations are given for some crops, but I cannot assume responsibility for success or failure of a growth regulator treatment. Growers should always consult their farm advisor or extension agent before using growth regulators, since recommendations are constantly changing and vary according to local climate and soil. Discussion of uses for plant regulators for agricultural corps does not necessarily imply that the United States Food and Drug Administration has approved all usages or that the compounds have been registered with the appropriate state or federal agencies. At the present time, with so much emphasis on improvement of the environment and prevention of pollution, registrations are in a state of flux - some of the old compounds are being eliminated and new ones are being added. Care should be taken that compounds are applied according to directions on the manufacturer's label as registered unter the Federal Insecticide, Funigicide, and Rodenticide Act. The recommendations on the label should be carefully followed and the local county agent or farm advisor should be consulted if a question or problem arises. Trade names are sometimes used in the text in combination with chemical names or abbreviations. This practice does not imply endorsement of any single product; trade names are given only as a convenience to the reader. This textbook is designed principally for classroom instruction and should be appropriate for a one-semester college course in plant growth substances. From my teaching experience I would suggest that Chapter 2 ("Biological and chemical Determination") can serve as the basis for a laboratory course in growth substances. The figures in this chapter that depict the procedures used in some of the bioassays should also prove helpful for such a course. An extensive documentation of the literature has been included to provide the reader with sufficient references for an in-depth study of any subject of particular interest. With the present trend toward increased independent study, an extensive literature review is essential.
