Advances in Tur/grass Science Management of Turfgrass Diseases SECOND EDITION by J. M. Vargas, Jr. Library of Congress Cataloging-in-Publication Data Vargas, J. M., Jr. Management ofturfgrass diseases I 1.M. Vargas, Jr.-{2nd. ed.] p. cm. Includes bibliographical references (p. ) and index. ISBN 1-56670-046-9 1. Turfgrasses-Diseascs. 2. Turf management. I. TItle. SB608.T87V371994 635.9'64293-dc20 93-28186 CIP This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with pennission. and sources are indicated. A wide variety of references are listed. Reasonable efforts have been made to publish reliable data and information, but the authors and the publisher cannot assume responsibility for the validity of all materials or for the consequences of their use. 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Visit the CRC Press Web site at www.crcpress.com o 1994 by CRC Press LLC Lewis Publishers is an imprint of CRC Press LLC No claim to original U.S. Government works International Standard Book Number 1-56670-046-9 Library of Congress Card Number 93-28186 To Rita and Joe My Mother and Father Thanks for everything J.M. Vargas, Jr., has been a professor of Botany and Plant Pathology for the past 25 years at Michigan State University, where he has been involved in teaching, research, and extension. He received his BS degree from the University of Rhode Island in 1963, his MS from Oklahoma State University in 1965, and his PhD from the University of Minnesota in 1968. Dr. Vargas has published over 200 articles on turf grass diseases and related subjects and has given over 1,000 presenta tions at conferences throughout the world, including Australia, New Zealand, South Africa, Japan, and Europe. His research accomplish ments include: • discovering the first bacterial disease in turf on Toronto creeping bent grass after many scientists failed to discover the problem; • reporting on the first resistance by a turfgrass pathogen to a systemic fungicide and later reporting the first resistance to the OMI fungicide by the dollar spot organism; • identifying the true cause of the black layer as excess sulfur in the soil; • demonstrating that annual bluegrass does not die from high tempera ture in cool season grass growing areas, but from two diseases, anthracnose and summer patch; • developing the first mathematical prediction model for a turfgrass disease; • developing a fungicide timing model for summer patch that is used throughout the world; • helping to develop the first biological control for annual bluegrass. Series Prefaee Turfgrass science is comparatively young compared to most areas of applied plant science. The first revolutionary breakthrough was the invention of the reel mower in 1830. Then in 1906 the first book, entitled Lawns and How to Make Them, was published by author Leonard Barron. This was followed by a number of books published in the next six decades that were based on the art of turfgrass culture, developed by trial-and-error methods for the most part. A small pool of basic knowledge of turfgrass science was developed through research in the 1920s and then was greatly extended after 1950. The publication of Turfgrass: Science and Culture in 1973 documented a new era in the science of turfgrass culture. The generation of research information and technical developments in turfgrass science has continued to accel erate even more rapidly since then. Now there is a need for yet more specific science-based books that encompass a practitioner orientation for the individual technical areas within the turfgrass science and culture fields. Accordingly, this ADVANCES IN TURFGRASS SCIENCE series has been developed as a coordinated, well-planned series of books encompassing the major areas of turfgrass science, culture, IPM, management, construction, and equipment. This book, Management of Turfgrass Diseases, by Dr. Joseph M. Vargas, Jr., addresses a major aspect of turfgrass science. It offers a science-based technical presentation for both the student and the prac titioner interested in the diseases of turfgrasses and their management. A key strength of the book is the author's integration of the individual turfgrass disease discussions with real-world cultural conditions. -Dr. James B. Beard vii Preface This book is written primarily for undergraduate students majoring in turf and turfgrass managers; i.e., golf course superintendents, lawn care operators, and landscapers. It contains the technical information necessary for decision-making in all areas of turfgrass management, as well as practical information useful in the day-to-day operation of turfgrass management programs. Although the emphasis is on diseases, all aspects of turfgrass culture are touched upon. In addition to helping readers solve the riddle of which grasses are resistant and which are susceptible to various dis eases, the book presents cultural and biological programs designed to keep the incidence of disease to a minimum on susceptible grasses, and fungicide recommendations for diseases that require such management. The book presents management strategies that take into account all aspects of turfgrass management (Le., diseases, cultivation, fertiliza tion, irrigation, mowing). This book differs from most texts on turfgrass management in that it is not simply a compilation of facts which the reader must evaluate. It lays out specific strategies that can be followed to prevent diseases from occurring. Not everyone can interpret which facts are valid and which are not. Interpretation and management strategies for successful turf grass management is what this book is all about. It must be remem bered that turfgrass management is an art based on science. I wish to sincerely thank James B. Beard, George W. Bird, Don Blasingame, Herb Cole, Phil Colbaugh, T. E. Freeman, Charles Gould, Bobby G. Joyner, W. A. Meyer, Noel Jackson. George Kozelnicky, Charles Laughlin, Bob E. Partyka, Kenyon T. Payne, Paul Rieke, Pat Sanders, Robert Shearman, Richard Smiley, Ward Stienstra, and A. J. Turgeon for editing various portions of the original text and for their excellent suggestions. Thanks also to Carolyn Brown, Sarah Pounder, and Chris Weiler, who gave valuable technical assistance, as did Hope Shepard, who also helped type the original manuscript, and to Linda Swain, who spent long hours typing and organizing the original manu- ix