Jim Nauis the greenhouses and gardens manager at Ball Horticultural Company, a recipient of the Perennial Plant Association&;s Garden Media Award, and a speaker at gardening conferences across the nation. He is the author of The Ball Culture Guide and The Ball Perennial Manual. He lives in West Chicago, Illinois.

Ball Redbook

Volume 2 Crop Production

By Jim Nau, Jayne VanderVelde

Ball Publishing

Copyright © 2011 Ball Publishing
All rights reserved.
ISBN: 978-1-883052-68-3

Contents

Preface,
Acknowledgments,
Part 1,
Introduction,
Water, Media and Nutrition,
1. Water Quality,
2. Media,
3. Plant Nutrition,
4. Managing pH for Container Media,
5. Water, Media and Nutrition Testing,
6. Temperature,
7. Light,
8. Growth Regulators,
Pest Control,
9. Managing Insects and Mites,
10. Managing Diseases,
11. Controlling Soilborne Pests,
12. Managing Resistance,
Propagation,
13. Propagating Seed Crops,
14. Propagating Vegetative Crops,
15. Indexing for Disease,
16. Postharvest Care and Handling of Flowering Potted Plants,
17. Sustainability,
Part 2: Crop Culture A-Z,
Appendix: USDA Hardiness Zone Map,
Bibliography,
Subject Index,
Plant Index,

CHAPTER 1

John M. Dole, Paul Fisher, and Brian E. Whipker

Water Quality

Poor quality water — whether it is high in electrical conductivity (EC), alkalinity, or waterborne pathogens — can make a grower’s life difficult. Water with a high EC can reduce seed germination, inhibit rooting of cuttings, and increase the likelihood of root and crown diseases. Water with an excessively high pH and alkalinity increases the likelihood of nutrient deficiency problems. The presence of waterborne pathogens in the water can eventually result in diseased plants. These problems are greatly magnified if you grow plugs and cuttings, because young plants are particularly sensitive to water quality.

Before we address water quality considerations, however, we need to discuss the practice of watering. For most crops the best plant growth is obtained when plants are irrigated just prior to wilting. Water stress reduces photosynthesis and slows growth. In addition, the cells of drought-stressed plants do not expand to their full potential, resulting in shorter, more compact plants. While limited drought stress can be beneficial for bedding plants such as bedding impatiens or tomatoes, plant quality is reduced on a majority of crops. Excessive drought stress can cause lower-leaf yellowing and damage roots, leading to disease. Excess water can lead to anaerobic conditions in substrate, also encouraging root diseases, nutrient deficiencies resulting from poor root function, and reduced root growth.

Generally the substrate should be watered thoroughly to the point that at least a small amount of water can be seen coming out of the bottom of the containers or beds. Insufficient watering can mean that part of the root-ball remains dry, or that salts such as sodium and chloride accumulate in the substrate. Irrigating with an excessively high volume of water will leach fertilizers from the growing substrate and increase the potential for runoff into the environment.

When hand watering, be sure to use a nozzle that breaks up the flow of the water and reduces the force of the water hitting the plants and the substrate. Using hoses without breakers at high volume will flush substrate out of the containers or cause compaction, resulting in reduced soil aeration. Automated irrigation systems are covered in volume 1 of the RedBook.

What Is High-Quality Water?

A variety of measures are used to determine chemical water quality (table 1–1).

One of the most important factors is the electrical conductivity (EC), a measure of total soluble salts. Water with a lo