conditions—pertaining to light, moisture, temperature, nutrients, and air—as well as improper cultural operation, involving compaction of soil and pesticide application, for example. Since these disorders are nonpathogenic, their effect is localized and usually within complete control of the grower. Further, since plant production under uncontrolled environmental conditions is subject to the uncertainties of the weather, certain disorders are unpredictable and sometimes difficult to prevent. This section is devoted to nonpathogenic disorders, many of which are weather related. Chapter 4 contains related information. Plants are not affected equally by adverse weather conditions. An important caution to observe when inspecting plants for disorders is not to hastily attribute every disorder to parasitic or pathogenic causes and exercise caution before initiating pest-control measures. 5.7.1 WEATHER-RELATED PLANT DISORDERS The following are different categories of weather factors and how they inflict damage on horticultural plants when they prevail in adverse levels. It should be emphasized that these factors often interact or interplay in producing an effect. The role of these factors in plant growth has been discussed previously. Temperature Extreme Cold Plants in temperate zones may suffer one of two kinds of injury from extremely cold temperatures. Similar to frostbite in humans, plants may suffer from frost damage when temperatures suddenly drop below seasonable levels. Affected plants may show signs of wilting overnight. When this cold strikes during the blooming period, the plant may lose most or all of its flowers. Frost damage occurs more frequently in younger tissues, and herbaceous species are more susceptible than woody ones. A much more severe cold damage called winter kill occurs when plants are subjected to prolonged periods of freezing temperatures. Under such conditions, branches may die back (tips wilt); when roots are severely impaired, however, the plant may die. In evergreens, such as pine, extreme cold may cause the foliage to “burn” (turn brown). Extreme Heat Microclimates, both natural and human-made, occur in the landscape in places such as underneath trees and the eaves of homes. Brick structures absorb heat during the day and radiate it at night. This property is advantageous during the cold months, because radiated heat protects plants in the vicinity from frost. However, in hot months, these same walls, especially those that face south, can create extremely hot microclimates, thereby injuring plants within their spheres of influence. Similarly, the hot asphalt of parking lots, concrete, and some pavements can radiate intense heat that damages plants. Heat-sensitive plants may show marginal scorching of leaves. Moisture Excess Moisture Excess moisture overwhelms the pore spaces in the soil leading to waterlogged conditions. Poorly drained soils create anaerobic conditions that lead to root death (root rot), if they persist for an extended period. Plants vary in their response to poor drainage. Root rot eventually results in plant death through stages, starting with stunted growth and yellowing and wilting. Excess moisture received after a period of drought might cause tubers and roots of root crops, as well as the walls of fruits such as tomato, to crack. Excess Dryness (Drought) leaves. Lack of moisture usually is expressed as wilting of plant Low Humidity The tips and margins of leaves of tropical plants brown (tip burn) under conditions of low humidity. This browning is caused by rapid transpiration, which overwhelms the rate at which water is moved through the leaf to the ends. As a result, water fails to reach the edges of the leaf, leading to drying and browning. 5.7 Nonpathogenic (Physiological) Plant Disorders 181
Light Intense Light Strong and direct sunlight may scorch certain plants. Potted plants placed in south-facing windows receive direct sunlight unless the presence of a tree in the direction of the sun’s rays filters the light. Intense light also causes the foliage of certain plants to bleach and look pale and sickly. Low Light Inadequate sunlight induces etiolated growth (spindly) and yellowing of leaves. Plant vigor is reduced, and leaves drop prematurely. Nutrients Nutrient Deficiency Generally, an inadequate supply of any of the major plant nutrients, especially nitrogen, causes plants to be stunted in growth and leaves to yellow (chlorosis). Deciduous plant leaves may prematurely senesce and defoliate. In addition to yellowing, lack of potassium shows up later as marginal leaf burns of leaves; young and expanding leaves show purple discoloration when phosphorus is lacking in the soil. Calcium deficiency in tomato shows up as blossom end rot. Nutrient Excess Excess acidic soils may cause excess availability of trace elements (e.g., iron and aluminum), which can lead to toxicity in certain plants. 5.7.2 HUMAN-RELATED ACTIVITIES Industrial Production Industrialized and heavily populated areas often experience excessive amounts of chemical pollutants in the air. These toxic gases damage horticultural plants. Acute amounts of sulfur dioxide cause chlorosis and browning of leaves and sometimes necrosis (cell destruction and death). Fluoride injury has been recorded in sensitive plants such as ponderosa pine as reddish-brown bands that appear between necrotic and green tissue. Ozone is a major pollutant that is produced primarily from the photochemical action of sunlight on automobile emission. It can cause chlorosis and necrosis in a wide variety of plants. Pesticide Application Improper application of pesticides may cause collateral damage to cultivated plants. Applying sprays on a windy day may cause the chemicals to drift onto desirable plants, resulting in deformed leaves, discoloration, and in some cases death of tissue and possibly the entire plant. Herbicide damage appears suddenly and may last through the cropping season. Often, the symptom is bleaching; in severe cases, it may be followed by leaf drop. Unlike the effect of herbicides, collateral damage from insecticides shows up as browning of the foliage. Fertilizer Application Chemical fertilizers are frequently applied to houseplants or outdoor plants in production. Eagerness for good yield may lead some growers to overfertilize their plants, resulting in a buildup of excessive fertilizer in the soil. High amounts of salts create sodic soil conditions. A higher salt-soil concentration than root fluids can cause dehydration of roots. Instead of the roots absorbing soil moisture, they become depleted of moisture. Plant growth is inhibited under such conditions, and plants wilt (as they would under drought conditions) and eventually die. 182 Chapter 5 Plant Physiology SUMMARY The variety of activities that have been described to occur at various phases in plant growth and development are the results of certain growth processes. These processes provide the raw materials and the energy required for building new tissues and nurturing
HORTICULTURE Principles and Practic
HORTICULTURE Principles and Practic
With love to Theresa, quarterback;
Brief Contents Preface xxi PART 1 T
Contents Preface xxi PART 1 THE UND
5.3 PLANT GROWTH PROCESSES 160 5.4
8.20 COMMON GREENHOUSE DISEASES 276
12.3 INTERNAL ENVIRONMENTAL CONTROL
PART 6 Summary 541 References and S
22.18 INDOOR COMPOSTING SYSTEMS 668
Preface Horticulture is the area of
ACKNOWLEDGMENTS I am very grateful
PART 1 THE UNDERLYING SCIENCE CHAPT
1 What Is Horticulture? PURPOSE AND
(a) (c) (b) (d) FIGURE 1-1 The many
FIGURE 1 Bridge. The plaza view of
CYCADS Many people mistake these pr
FIGURE 2 The world's largest unbran
FIGURE 2 Sold flowers are loaded on
FIGURE 1-4 Formal landscaping featu
1.4 ROLEOFTHENURSERY AND SEED INDUS
1.5 HORTICULTURE AND SOCIETY Hortic
TABLE 1-3 U.S. Horticultural Export
Turfgrass Operation 1. Landscape te
What Is Horticulture? This site pro
Examples of botanical gardens http:
2 Classifying and Naming Horticultu
Eight major taxa are commonly used
TABLE 2-3 The Divisions of the King
HISTORY OF PLANT TAXONOMY PAUL R. F
AGE OF HERBALISTS Two major events
possible system of nomenclature. Ho
TABLE 1 Type Categories for Plant N
2.3 OTHER CLASSIFICATION SYSTEMS (O
2. Shrubs. A shrub has no main trun
Simple Fruits Fleshy Fruits Drupe B
FIGURE 2-14 A pome, represented by
2.3.5 CLASSIFICATION OF VEGETABLES
(a) (b) FIGURE 2-22 (Source: George
FIGURE 2-25 A narrowleaf plant. (So
FIGURE 2-29 Parts of a typical gras
such as rosemary, sage, thyme, marj
c. Leaves d. Bulbs 2. Cut across (t
Whole plant Organs FIGURE 3-1 Level
ibonucleic acid (RNA), proteins, an
called cristae; this extreme foldin
By virtue of its position, the prim
Phloem Tissue Structurally, phloem
(a) Stalk (b) Culm FIGURE 3-5 Cross
Scale Compressed stem (a) Whole bul
Upper epidermis Palisade layer FIGU
usually occur in xerophytes. In cer
FIGURE 3-22 Selected common leaf ma
FIGURE 3-25 Selected common leaf ti
absorption of water and minerals fr
Outer bark Inner bark FIGURE 3-37 T
Anther Filament Stamen FIGURE 3-41
Exocarp Parts of a typi- FIGURE 3-4
PRACTICAL EXPERIENCE LABORATORY 1.
4.1 CLIMATE, WEATHER, AND HORTICULT
concentration in the atmosphere.A c
TABLE 4-1 Climatic Adaptation of Se
and upward. Another important gener
Rate of photosynthesis mg/sq. dm/hr
and plants that flower under only c
times of the year. Growers start th
content. This section is sometimes
TABLE 4-7 Soil Mineral Nutrients Es
Micronutrients (Trace Elements) Mic
Neutral FIGURE 4-11 A representatio
4.4 FERTILIZERS Fertilizer sources
One of the most commonly used contr
Chlorosis (the yellowing of green l
Fertilizers may be applied before p
It is neither practical nor safe to
Solution: How much of ammonium nitr
1°C (34°F), the optimum temperatu
TABLE 7-1 Selected Fungal Diseases
7.6.1 SMALL ANIMALS Rabbits, mice,
FIGURE 7-16 The disease triangle. P
fungitoxic exudates in its leaves,
SUMMARY Insects are a major class o
For the home growers or those who c
for consumers and the environment).
TABLE 8-1 Strategy 4: Strategies an
gibberellic acid spray overcomes st
In a competitive industry, a variet
Chemicals gain access to humans thr
2. Pesticide management. Controllin
Every organism has its natural enem
TABLE 8-3 Selected Examples of Biol
1 2 YEAR 3 4 FIGURE 8-5 cycle. A cr
6. Heat treatment. In the greenhous
Organic Compounds (Organics) Organi
under enclosed conditions (e.g., wa
FIGURE 8-9 A tractor-mounted spraye
8.11.9 LANDSCAPE PESTS AND THEIR CO
application, a particular herbicide
Further, they do not provide unifor
SUMMARY Herbicides are chemicals us
Sulfur may be applied for both prev
8.23 PREVENTING GREENHOUSE DISEASES
PART 3 PROPAGATING HORTICULTURAL PL
9 Sexual Propagation PURPOSE AND EX
Anther Microspore Megaspore mother
Lettuce seeds Red light Darkness Fa
FEDERAL AND STATE SEED LAWS Federal
Germination Test In laboratory prac
FIGURE 15 The essential structures
processing into flour or meal). How
physiologically immature seeds must
seeds may be treated in this way be
The two basic modes of seedling eme
locations in the field. Home garden
FIGURE 9-9 A plastic flat. (Source:
(a) (b) FIGURE 9-12 (a) Sowing seed
y the gardener or grower. Whatever
REFERENCES AND SUGGESTED READING Co
species enables vegetative propagat
for rapid rooting. There are two ba
Cutting involving one node (e.g., s
This practice is especially importa
10.6.4 STICKING THE CUTTING Cutting
(a) Indexing by budding Diseased pl
10.11 M ETHODS OF GRAFTING Grafting
Scion Wax FIGURE 10-17 Steps in bar
MODULE 3 BUDDING 10.12 TYPES OF BUD
MODULE 4 LAYERING 10.13 TYPES OF LA
Buried part of shoot is nicked FIGU
variety of ways. In air layering, a
FIGURE 10-34 by using cormels. Prop
Psuedobulbs In the Dendrobium orchi
The technique is used widely in cro
PART 4 GROWING PLANTS INDOORS CHAPT
11 Growing Houseplants PURPOSE AND
TABLE 11-1 Common houseplants Commo
Saddle leaf Philodendron selloum To
Window Displays Plants in windows e
CONTAINER GARDENS DR. TERRI W. STAR
annuals and hardy perennial species
of the large container filled with
perfection about four to six weeks
FIGURE 11-6 Flowers displayed on th
TABLE 11-5 Plant Selected Plants fo
The lighting condition near these w
Fluorescent Lights Fluorescent ligh
may be used for one pot or a group
garden rooms, atriums, or a large c
The photoperiod affects when the ho
patted firm to keep the plant erect
Other Materials Apart from clay and
(a) ( FIGURE 11-25 Support for plan
TABLE 11-7 Common Problems of House
• Keep soil moist all the time
• Prefers high temperatures • P
amount and quality of light. If sup
12 Controlled-Environment Horticult
6. Curvilinear 7. Curved eave 8. Do
Detached greenhouses have several a
12.2.3 FRAME DESIGN There are two b
horticultural business a less-expen
Texas, Hawaii, and California. The
source of heat for times when the t
FIGURE 12-17 Greenhouse production
FIGURE 12-21 Moving tables allowing
Research program on greenhouse engi
greenhouses equipped with a variety
FIGURE 1 Annual energy required per
This system was demonstrated in a 5
FIGURE 6 Amounts of waste energy ut
Ekholt, B.A., D.R. Mears, M.S. Gini
or object to be warmed. Failure to
objects in its path (e.g., the floo
FIGURE 12-27 Motorized ventilation
FIGURE 12-30 Movable internal shade
FIGURE 12-33 A high pressure sodium
Source of Water The quality of loca
FIGURE 12-37 Overhead sprinkler irr
Intermittent Feed Greenhouse plants
However, in winter, greenhouse vent
OUTCOMES ASSESSMENT 1. Explain the
. Foliage or green plants. Foliage
2. Labor. The size of the labor for
FIGURE 13-1 Greenhouse production o
FIGURE 13-2 Lettuce plug is inserte
13.8.4 AGGREGATE HYDROPONIC SYSTEMS
(a) (b) (c) FIGURE 13-6 Plug produc
14 Growing Succulents PURPOSE AND E
FIGURE 14-3 Leaf succulent represen
frost-hardy. Their rosettes are usu
TABLE 14-1 Plant Selected Popular S
(a) (b) FIGURE 14-12 Typical bromel
14.7.1 WHAT ARE CACTI? 14.7 CACTI C
FIGURE 14-16 Opuntia. (Source: Crai
FIGURE 14-23 Mammillaria. (Source:
FIGURE 14-28 Both desert and jungle
Growing mix Gravel Cacti (a) (b) FI
PART5 GROWING PLANTS OUTDOORS: ORNA
15 Principles of Landscaping PURPOS
8. Create recreational grounds. Suc
knowledge, with concern for resourc
(a) (b) (c) FIGURE 15-2 The occurre
GUIDELINES FOR LANDSCAPE DESIGN DAV
the landscape. Some very successful
Rhythm and Line Panoramic view of a
FIGURE 15-10 A formal garden. The e
How frequently do they entertain? A
the patio should be located on the
15.7.1 SELECTING PLANTS A homeowner
Plant Arrangement in the Landscape
Shadow FIGURE 15-15 Planting a tree
SUMMARY Landscaping enhances the su
3. Supply materials on a timely bas
such as preparation rooms (for mixi
of environmental fluctuations. Furt
FIGURE 16-4 A bare-root tree seedli
17 Installation of the Landscape PU
for walks, driveways, and patios (F
Planting may be limited to accentin
17.3.3 PREPARING THE BED The soil s
FIGURE 17-4 Bedding plants raised i
SUMMARY Bedding plants are largely
TABLE 17-6 Selected Ground Covers T
TABLE 17-7 Selected Ornamental Gras
they determine the success and surv
12. Wildlife attraction. Trees in t
pennsylvanica), hackberry (Celtis s
y winds. A stake, which is often a
TABLE 17-8 Selected Narrowleaf Ever
TABLE 17-11 Selected Deciduous Shru
Blooming bushes 1. Blue mist shrub
Planting Bulblets and Bulbils Speci
may be divided such that each secti
FIGURE 18-1 (Source: George Acquaah
Cool-Season (Temperate) Grasses In
Growth Habit Turfgrasses are the mo
Heavy Use Lawns on playgrounds and
The seed should be free from weeds
Source of Sod As with seed, sod sup
A plug of sod FIGURE 18-7 Plugging
way, plants are able to adapt to th
form of a can placed on the lawn wi
TABLE 18-3 Some Common Lawn and Tur
even surface soil surface for layin
MacCaskey, M. 1987. All about lawns
Pruning is sometimes done in conjun
4. Pruning may be done to reduce th
19.4.2 SAWS A saw may be designed t
defeat the purpose of pruning. The
Bud withers as cut end dries back d
19.6 STRATEGIES FOR PRUNING ABOVEGR
Rejuvenation Pruning Cut canes to a
3. In the third and subsequent year
(a) Cut Prune (b) FIGURE 19-16 Step
Eucalyptus and Paulownia are amenab
TRAINING & PRUNING DECIDUOUS FRUIT
Summer pruning eliminates an energy
a) b) FIGURE 2 Newly planted apple
FIGURE 6 Wooden limb spreaders can
FIGURE 9. An apple tree trained to
years to promote continued lateral
Horizontal Espalier The horizontal
19.16.1 CANE FRUITS Cane fruits are
FIGURE 19-26 Shearing of Christmas
pyramid-like form that is wider at
After selecting the appropriate spe
PART 6 GROWING PLANTS OUTDOORS: VEG
20 Growing Vegetables Outdoors PURP
The National Agricultural Statistic
(This item omitted from WebBook edi
growers should take to determine an
pests and reduce/ eliminate hail da
square yard (10 to 68 grams per squ
High tunnels help increase the prof
(This item omitted from WebBook edi
20.4 VEGETABLE MARKET TYPES Fresh V
Establishing the Crop Planting into
home water supply from the tap. Thi
Cole crop Cabbage Root Potato Bean
6. Adequate nutrition. While overfe
variable, ranging from creamy yello
There are two general production pr
This toxin is heat resistant and no
large, or jumbo. The bulb may be sw
REFERENCES Growing selected vegetab
TABLE 21-1 Popular Herbs and Their
(a) (b) (c) (d) (e) (f) FIGURE 21-1
22 Organic Farming PURPOSE AND EXPE
22.3 PRINCIPLES OF ORGANIC FARMING
and the specific materials to be us
22.8 MANAGING SOIL PHYSICAL QUALITY
preemergent or early postemergent o
Composting is a deliberate activity
22.14.5 THE CARBON-TO-NITROGEN RATI
Moisture Supply Water is required b
Compost materials FIGURE 22-4 a wir
As microbial decomposition proceeds
Establishment and Management of an
night, freezing can occur in spring
accomplished by stratification. It
transmitted by the dagger nematode
PART 7 SPECIAL TECHNIQUES AND HANDL
24 Cut Flowers and Floral Design PU
to more than four-fold in standard
Temperature and Humidity Wilting re
FLORAL DESIGN: AN OVERVIEW BY WM. J
Principle Definition Types (or Uses
pH value-a measure of the acidity o
FIGURE 6 Parallel Design-Parallel d
24.3.2 TOOLS AND MATERIALS The tool
3. Establish the focal point. 4. Ad
Natural Drying To dry naturally, fl
24.4.3 DRIED FLOWER ARRANGEMENTS Dr
25 Terrarium Culture PURPOSE AND EX
FIGURE 25-3 Terrarium containers ar
FIGURE 25-5 Assortment of tools use
25.6.7 ENHANCING THE DISPLAY Certai
(a) (b) FIGURE 26-1 Bonsai can be c
TABLE 26-3 Plant A Selection of Pop
26.3.1 COLLECTING BONSAI PLANTS FRO
Strip bark Bare branch FIGURE 26-9
26.5.2 SANITATION It is critical to
27 Postharvest Handling and Marketi
whereas oranges are picked (they ha
(b) (a) (c) (d) (e1) (e2) (f) FIGUR
To reduce packaging injury, contain
is replaced by the by-product of re
Stored produce may lose some color,
with pricing. When selling by volum
(a) (b) FIGURE 27-5 Horticultural p
APPENDIX A Temperature: Converting
APPENDIX B Metric Conversion Chart
APPENDIX D Common and Scientific Na
Pecan (Carya illinoensis) Peony (Pa
GLOSSARY A Abaxial Turned away from
Cellulose A complex carbohydrate th
Floriculture The science and practi
M Macronutrient An essential elemen
Root cap A mass of hard cells cover
INDEX A-frame, 395 A-horizon, 108 A
defined, 390 fertilization, 432-434
Radiant heaters, 378 Radicle, 90 Re
color plate 1 (a) (b) (c) (d) (e) M
color plate 3 (b) (a) (c) (d) (e) (
color plate 5 (a) (b) (d) (c) (e) (
color plate 7 (b) (c) (d) (a) (e) (
color plate 9 (a) (b) (c) (d) (e) (
color plate 11 (a) (c) (b) (d) Grow
color plate 13 (a) (b) (c) (d) (e)
color plate 15 (a) (b) (c) (d) (e)
color plate 17 (a) (b) (c) (d) (e)
color plate 19 (a) (b) (c) (d) (e)
color plate 21 (a) (b) (c) (e) (d)
color plate 23 (c) (b) (a) (d) (e)
color plate 25 (c) (a) (b) (d) (e)
color plate 27 (a1) (a2) (b2) (b1)
color plate 29 (a) (b) (c) (d) (e)
color plate 31 (a) (b) (c) Floral d
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Magazine: Horticulture Principles and Practices