What’s Wrong with My Marijuana Plant?: A Cannabis Grower’s Visual Guide to Easy Diagnosis and Organic Remedies

423 Pages·2017·67.81 MB·English

by  David C. Deardorff

Copyright © 2017 by David Deardorff and Kathryn Wadsworth
All rights reserved.
Published in the United States by Ten Speed Press, an imprint of the Crown Publishing
Group, a division of Penguin Random House LLC, New York.
www.crownpublishing.com
www.tenspeed.com
Ten Speed Press and the Ten Speed Press colophon are registered trademarks of
Penguin Random House LLC.
Library of Congress Cataloging-in-Publication Data Names: Deardorff, David C., author. |
Wadsworth, Kathryn B., author.
Title: What’s wrong with my marijuana plant? : a cannabis grower’s visual guide to easy
diagnosis and organic remedies / David Deardorff and Kathryn Wadsworth.
Description: First edition. | California ; New York : Ten Speed Press, 2017. | Includes index.
Identifiers: LCCN 2017011486
Subjects: LCSH: Cannabis—Diseases and pests. | Cannabis—Diseases and pests—Control.
Classification: LCC SB608.C28 D43 2017 | DDC 633.5/3—dc23
LC record available at https://lccn.loc.gov/2017011486
Trade Paperback ISBN 9780399578984
Ebook ISBN 9780399578991
Production by Howie Severson
Cover design by Betsy Stromberg and George Carpenter, based on a design by Susan
Applegate All photographs are by the authors except for the following: Ana Marguerite
Deardorff: this page, this page, this page, this page, this page
John Sanders: this page
John Schneider: this page
v4.1
a
This book contains information on growing cannabis, which is a controlled substance in
North America and throughout much of the world. As the use and cultivation of cannabis
and its derivative products can carry heavy penalties, you should research your local laws
before using the information in this book. Any attempt to treat an illness using cannabis
should also be done under the direction of a health care professional. The authors and the
publisher expressly disclaim any liability, loss, or risk, personal or otherwise, which is
incurred as a consequence, directly or indirectly, of the use and application of any of the
contents of this book.
CONTENTS
Introduction
PART I—WHAT’S WRONG? VISUAL PROBLEM-SOLVING
GUIDES
Chapter One—Problems on the Whole Plant
Chapter Two—Problems on Leaves
Chapter Three—Problems on Flowers and Flower Buds
Chapter Four—Problems on Stems
Chapter Five—Problems on Roots
Chapter Six—Problems on Seeds and Seedlings
PART II—HOW DO I FIX IT? ORGANIC SOLUTIONS
Chapter Seven—Change the Growing Conditions
Chapter Eight—Use Biological Controls
Chapter Nine—Use Organic Chemical Remedies
Chapter Ten—Create Healthy Growing Conditions
Chapter Eleven—Manage Nutrients
Chapter Twelve—Manage Light
Chapter Thirteen—Manage Water
Chapter Fourteen—Manage Temperature and Humidity
Chapter Fifteen—Use Proper Pruning Techniques
Chapter Sixteen—Use Proper Propagation Techniques
Resources
Acknowledgments
About the Authors
Other Books by Deardorff and Wadsworth
Index

For researchers, patients, and families who
have the courage to discover more about this
remarkable plant and to seek treatment for
debilitating illnesses.
INTRODUCTION
Whether you are a home grower with a couple of marijuana plants
or a commercial grower with hundreds of plants, this book will help
you diagnose problems and find solutions. Disorders (such as
unhealthy growing conditions), pests, and diseases are all included
here. You can treat all these problems by improving growing
conditions, using biological controls, or applying safe, organic
remedies.
We are botanists, plant pathologists, and writers. We’ve owned
nurseries and traveled the world on botanical adventures. In this
book, we have compiled the most recent research to help you grow
healthy cannabis. The United States government considers
cannabis an illegal crop, resulting in no U.S. Department of
Agriculture (USDA) guidelines, no Environmental Protection Agency
(EPA) standards, and virtually no university research on acceptable
treatments for pests and diseases or on the efficacy of those
treatments. Research on organic cultivation of cannabis is
relatively limited. To find the best organic methods, we have
worked with licensed legal growers who use organic practices and
we have relied on research from European sources, the Organic
Materials Review Institute (OMRI), and other scientific literature.
Every state in the United States that has legalized marijuana has
its own statutes and guidelines. Be sure to find out what is
permitted in your location, because we are not legal experts.
Finally, we are not medical practitioners and have conducted no
research on the medicinal attributes of marijuana. Please consult
with your doctor or health care practitioner for advice on its
medicinal uses.
WHY USE ORGANIC GROWING
TECHNIQUES?
Whatever your intended use of cannabis—whether as a medicine,
relaxant, mood enhancer, ritualistic practice aid, or vehicle to alter
perception—you must inhale, ingest, or otherwise absorb its active
ingredients. Any nonorganic, synthetic pesticide used on plants
winds up inside you. Synthetic chemicals such as pesticides
damage human health and the living community of which we are a
part. Choose organic techniques to protect yourself and the
environment.
No matter where cannabis is grown, virtually no health and
safety standards exist for growing it. Because it is considered
illegal in many places, research is lacking and testing is not
standardized. Recent media coverage has revealed that pesticide
residue on marijuana is an escalating problem. Labs that have
performed tests have frequently found contaminants such as
pesticides and heavy metals. These pesticides include fungicide
and insecticide residues at levels sixteen-hundred times higher
than the legal limit for food plants. This is alarming. It just makes
sense to do everything possible to eliminate this threat to the
health of cannabis growers, users, and the biosphere.
ABOUT CANNABIS
People have cultivated cannabis for medicinal, spiritual, and
recreational purposes for ten thousand years. In 2008, an
archeological dig of a shaman’s grave in China revealed the
earliest record of its medicinal use some twenty-seven-hundred
years ago, and evidence shows that ritual use is more than four
thousand years old. Recreational and mood-altering uses are likely
just as ancient. The Greek historian Herodotus, writing in 440 BCE,
mentions its euphoric effects in his Histories. In more modern times,
people have made paper, clothing, and rope from hemp fiber and
oil and milk from the seeds.
Because of our relationship with this important plant, humans
have carried cannabis around the globe for so long that it’s difficult