Title: Diagnostic and monitoring procedures for nursery crops
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00027961/00001
 Material Information
Title: Diagnostic and monitoring procedures for nursery crops
Physical Description: Book
Creator: Ingram, Dewayne L.
Publisher: Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida,
Publication Date: 1990
Copyright Date: 1990
 Record Information
Bibliographic ID: UF00027961
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: electronic_aleph - 003320274
electronic_oclc - 60884106

Full Text

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For Commercial Use Only

Florida Cooperative Extension Service
Institute of Food and Agricultural Sciences

University of Florida
John T. Woeste, Dean for Extension

Circular 556

Diagnostic and Monitoring
Procedures for
Nursery Crops

Dewayne L. Ingram, Richard W. Henley, and Thomas H. Yeager

Dewayne L. Ingram is a former professor and woody ornamental specialist, Gainesville; Richard W. Henley is a professor and foliage
specialist, Apopka; and Thomas H. Yeager is an associate professor and woody ornamental specialist, Gainesville; Environmental
Horticulture Department, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida 32611

Producing container-grown ornamental crops,
using available technology, requires intense cultural
practices and high levels of management skills.
Growers must make decisions based on an accurate
assessment of economic considerations as well as
environmental, physical, chemical, and biological
factors that influence plant growth. Grower ex-
perience is invaluable, but even the most experienced
grower needs accurate monitoring of the crop en-
vironment to make many decisions pertaining to crop
All nurseries should be equipped to make routine
measurements of the physical and chemical status of
container media such as water-holding capacity, non-
capillary pore space, pH, and media solution conduc-
tivity. The pH and conductivity measurements are
also useful for evaluating irrigation water quality.
Nursery operators who grow crops requiring specific
light intensities for optimum growth should have a
light meter to measure light levels in production
areas. Pest identification and examination of plants
or plant parts injured by pests or physiological disor-
ders can be greatly assisted by optical aids housed in
the nursery laboratory.

General Requirements

The nursery laboratory should be adequately
large, with clean, efficient work and storage spaces,
reliable instruments, and adequate supplies. The
space necessary will depend upon the specific proce-
dures performed routinely. One trained person
should be in charge of laboratory operation and
maintenance. For small nursery businesses, this
person will probably be the owner/operator.
A job description for the laboratory manager or a
procedures manual for small nurseries is necessary
to ensure consistent procedures and efficient labora-
tory use. The job description/procedures manual
should include general responsibilities, specific tests
to be conducted, detailed test procedures, an opera-
tions schedule, a record-keeping method, and a
system of reporting or using the information generat-
ed. Laboratory accomplishments must be evaluated
on a consistent basis by the nursery manager, and
laboratory procedures should be changed as neces-
sary. Failure to follow such a rigid format of plan-
ning, implementation, and evaluation can result in a
wasted investment, even for small nurseries.

Ideally, the laboratory should be located in a
special room, but a room with a compatible activity,
such as the grower's office, can be satisfactory. The
laboratory should be in an air-conditioned area free

from heavy dust, excessive humidity, and tempera-
ture extremes; these conditions reduce the life
expectancy and accuracy of laboratory instruments.
An area of 7 to 9 square meters (75 to 97 square
feet) is required for nurseries conducting several
routine monitoring/diagnostic procedures, and a room
with a 3 to 5 ratio of width to length is most effi-
Counter space should be adequate for the instru-
ments, record books, sample preparation, and clean-
up. Four square meters (43 square feet) of counter
space and 5 cubic meters (180 cubic feet) of storage
space in cabinets and drawers are the minimum
required. A water supply and sink with a large trap
in the drain pipe are essential for soil test proce-
dures. Cabinets above and/or below the counter
should provide sufficient storage space for supplies,
reference books, and possibly some small equipment
Counter and floor cabinet depths of 56 to 76 cm
(22 to 30 inches) and wall cabinets of 30 to 46 cm
(12 to 18 inches) are most common. An L-shaped or
U-shaped counter is generally more efficient than a
long counter, and careful instrument placement will
further minimize wasted personnel motion and time
(Figure 1). Counters 90 cm (36 inches) high are
most comfortable for laboratory activities, but a desk
or small counter area at a comfortable sitting height
(30 inches, 76 cm) with adequate leg space would be
useful in the laboratory.

The nursery laboratory must have sufficient glass-
ware and supporting items to make required mea-
surements. These supplies can be purchased from
scientific chemical supply companies or nursery
supply dealers. Supplies and other small items
needed include:
Vacuum aspirator
Filtering flask
Buchner funnels (1 to 4)
Glass beakers (250 to 500 mL)
Filter paper (to fit Buchner funnel)
Rubber or neoprene hose (to fit aspirator &
Distilled or deionized water
pH buffer solutions of pH 10.0, 7.0, and 4.0
Squeeze water bottle
Glassware drying rack
Laboratory grade soap (such as Alconox)
Glass stirring rods
Buckets or pans
Masking tape
Graduated cylinders (50 to 100 mL)

Nonabrasive tissue
Soil sampling tool

Instruments and Measurement Procedures

Electrical Conductivity
A solubridge, or conductivity meter, with a con-
ductivity cell is needed to measure electrical conduc-
tivity in media and irrigation water. Conductivity
meters measure the electrical conductivity of solu-
tions, and dissolved salts increase the conductivity.
Most fertilizers are salts, and because the media
concentration of salts is related to electrical conduc-
tivity, this can be used as an indicator of the need
for additional fertilizer or for the removal of excessive
salts from the media.
Some fertilizer carriers are not salts, such as urea,
and do not affect the electrical conductivity of solu-
tions. However, for guiding fertilization management
and monitoring the effects of irrigating with saline
water in container-grown plants, conductivity mea-
surements are most useful when taken frequently
enough to detect trends and dramatic changes.

The Beckman Solubridge (Model SDB-15) with a
conductivity cell (Model CEL-VS2) and Myron L
Agri-Meter are commonly used in the nursery
industry. They cost approximately $200, whereas
more sophisticated conductivity meters and cells cost
between $300 and $800. Suppliers of conductivity
meters include: Capitol Agricultural Service and
Supply Co., P.O. Box 3508, Montgomery, AL 36193;
E. C. Geiger, Box 285, Harleysville, PA 19438; A. H.
Hummert Seed Company, 2746 Chouteau Avenue,
St. Louis, MO 63103; Fisher Scientific, 7464 Chancel-
lor Drive, Orlando, FL 32809; and Baxter Healthcare
Corporation, 1430 Waukegon Road, McGraw Park, IL
Excessive salts cause injury to root systems, ul-
timately restricting water and nutrient uptake. This
results in wilting and leaf tip and margin burn of
new or recently matured leaves. Leaf chlorosis and
nutrient deficiency symptoms can indicate a non-
functional root system. Periodic testing is important,
as moderate to high salts levels may not be ex-
pressed by visible symptoms, although growth is
reduced. Excessive concentrations of salts can result
from medium components, irrigation frequency and
duration, water source, and/or fertilizer materials
and application methods. Heavy rainfall can also
leach nutrients from the container medium. Media
for long-term crops should be tested at least monthly,
but weekly sampling during the summer may be
necessary to track fluctuations in electrical conduc-
tivity. Knowledge of conductivity fluctuations helps

Figure 1.


II ~ I





nursery operators optimize fertilization rate and
application frequency.
Collection and Sample Preparation. Collec-
tion of representative medium samples is necessary
for accurate conductivity determinations. Salts may
accumulate in specific locations in media due to
water movement patterns and fertilization methods.
Therefore, one isolated sample may not give an
accurate representation of the conductivity or nutri-
ent status of the growth medium as a whole.
Several methods are used to obtain liquid extracts
from container media needed for electrical conduc-
tivity, pH, and other nutritional parameter deter-
minations. The optional methods available to nur-
sery operators include the 2:1 dilution procedure,
saturated paste, and the Virginia Tech extraction
procedure (also referred to as the pour-through
The 2:1 and the saturated paste procedures
require removing media from the container. With a
soil probe or narrow trowel collect 15 to 20 sample
cores from containers of a representative bed or area,
and blend the samples together into one uniform
sample. The upper layer of container media cores
may be disturbed and should be discarded. Save
about 250 mL (1/2 pint) of the total sample for
testing. Additional details for sampling are given in
Container Media Test Information Form 2674,
available from the county extension office.
Mix two volumes of distilled water with one
volume of media for the 2:1 dilution procedure, and
allow the mixture to sit for 2 to 6 hours. Time is
not crucial, but must be consistent for all samples
and sampling times. Maintain accuracy and consis-
tency with each sample when using the 2:1 method.
The saturated paste procedure involves saturating
a 200 mL (0.8 cups) volume of container medium
with distilled water. Slowly add distilled water while
stirring until the medium surface is shiny, but no
free water moves across it when the beaker is tilted.
For best equilibration of salts, allow the saturated
sample to sit for 2 to 6 hours. Extract the med-
ium solution by vacuum filtering the saturated med-
ium (Figure 2).
The Virginia Tech extraction procedure consists of
watering a container plant and allowing time for
drainage (2 hours to overnight) in order for the salts
level in the medium to reach equilibrium. After this
equilibration period, the container must be elevated
above a collection container so that leachate or
extract is not contaminated with debris or salts on
the perimeter of the container (Figure 3). The
bottom or sides of the container should not be wiped
before collecting leachate.

Figure 2.

Figure 3.

Apply distilled water (in a circular motion) to the
growth medium surface to yield 30 to 50 mL of
leachate from the container. Leachate should be
collected from 5 to 10 containers per production bed
or area to obtain an average value that is representa-
tive of the growth medium nutritional status. This

method of leachate collection allows for quick deter-
minations of extract or leachate electrical conduc-
tivity, pH, or elemental concentrations.
Irrigation water conductivity can be measured
directly with a meter, and the parts per million of
soluble salts calculated. Interpretation of meter
readings and parts per million of soluble salts in
irrigation water is given in Table 1. Injected fer-
tilizers will increase the electrical conductivity of
irrigation water. Irrigation water electrical conduc-
tivity, pH, and elemental concentrations should be
monitored periodically. Water samples for elemental
concentration determinations may be sent by the
county extension office to the University of Florida
Extension Soil Testing Laboratory, or samples can be
sent to a commercial laboratory.

Table 1. Interpretation of soluble salts levels in Irriga-
tion water for ornamental crops.

Meter Readings
mhosx 103/cmordS/m

Salts (ppm)
> 980


Adapted from Waters, W.E., J. NeSmith, C.M. Geraldson and S.S.
Woltz. 1972. The interpretation of soluble salts tests and soil analysis
by different procedures. Bradenton AREC memo Report GC-1972-4.
dS/m = decisiemens per meter.

Measurement and Interpretation. The con-
ductivity meter is calibrated with a 0.01 normal
potassium chloride (KC1) solution or with a test
solution supplied by the manufacturer. A 0.01
normal KCl solution has an electrical conductivity of
1.4 mmhos/cm. Units for most meters used in the
nursery industry are mmhos/cm (mhos/cm x 103),
although the units for some meters are mhos/cm x
10-5. Therefore, the electrical conductivity of the
calibration solution using meters with these scales
would be 1.4 mhos x 103 and 140 mhos x 10"5,
respectively. See the instruction manual if calibra-
tion is necessary.
The calibration solution must be at the same
temperature as the samples of extract. Rinse the
electrode with distilled water and blot dry. Immerse
the electrode in the extract and record the reading.
Remove the electrode, rinse with distilled water, and
store immersed in distilled water. In order for
comparisons to be made from sample to sample and
from samples taken at different times, consistency in
taking measurements is very important.
Interpretations are given in Table 2. Ranges
given correspond to most ornamental plants; howev-
er, adjustments must be made for plants known to

be salt sensitive. For example, azaleas are salt
sensitive, and the optimal conductivity level is about
one-half that of nonsensitive plants. Values in Table
2 are based on the saturated paste procedure, but
are also used for interpreting the Virginia Tech
procedure. Values for the 2:1 procedure are not
given, but are about one-half those of the saturated
paste values (except for pH, which is the same).
Additional details for these extraction procedures are
given in Video Tape 217, available from the county
extension office.

pH Measurement
A pH meter is used to measure acidic or alkaline
reactions of media solutions or irrigation water. It
measures the negative log of the hydrogen ion
activity. A pH meter can be purchased for $100 to
$900, depending upon the accuracy and options
desired. A meter with accuracy of + 0.1 pH and
repeatability of + 0.05 pH is generally adequate for
a nursery laboratory. Models that are AC powered
and/or battery powered are available. Take care to
evaluate a pH meter on accuracy and durability be-
cause there are meters on the market not suited for
commercial use.
Some manufacturers or distributers of popular pH
meters include Cole-Parmer Instrument, Fisher
Scientific, and Orion Research. Meters may be
purchased from manufacturers, nursery equipment
suppliers, or laboratory supply companies such as
those listed previously.
Proper care and storage of meters and electrodes
will ensure long life. Electrodes of routinely used
meters should be inserted into distilled or deionized
water and the meter switched to "stand-by" or "off'
when not in use.
A pH meter is calibrated with buffer solutions of
pH 10.0, 7.0, and 4.0. Buffers can be purchased
from companies that supply pH meters. Place the
electrode in the pH 7.0 buffer and allow time for
equilibration. (Pour the buffer solution into a small
beaker. Do not insert the electrode directly into the
stock buffer solution.) Then use the meter calibra-
tion dial to adjust the meter to 7.0. Remove elec-
trodes from the buffer and wash thoroughly with
distilled water (a squeeze bottle with a spout works
well) and blot dry with a nonabrasive tissue.
Place electrodes in the pH 4.0 buffer and adjust
the meter reading using the slope/temperature dial
after equilibrium has been reached. The calibration
dial should not be moved during this step. Read the
pH 7.0 buffer again after washing the electrode and
if no or only slight adjustment is necessary the
meter is calibrated. The electrodes can be placed in
the pH 10 buffer to check the calibration. If more
adjustment is required, repeat the entire procedure.


Table 2. Interpretation of container medium test.*
Analysis Rating Category
Low Acceptable Optimum High high
pH < 5.0 5.0 to 5.5 5.5 to 5.8 5.8 to 6.5 > 6.5
Electrical conductivity, dS/m <0.7 0.7to 1.0 1.0 to 1.5 1.5 to 3.0 > 3.0
Nitrate-N, mg/L <40 40 to 80 80 to 100 100 to 200 > 200
Phosphorus, mg/L <3 3to8 8to 12 12 to18 >18
Potassium, mg/L <10 10 to 20 20 to 40 40 to 80 >80
Calcium, mg/L <10 10 to 20 20 to 40 40 to 100 >100
Magnesium, mg/L <10 0 to 15 15 to 20 20 to 60 >60
* Plants of the Ericaceae family (e.g., azaleas) and salt-sensitive plants require only one half the electrical conductivity amounts and can tolerate only one half the
levels of nutrients (NO -N, P, K, Ca, and Mg) shown in this table.

Meters for determining pH differ in accuracy, and
some may not calibrate exactly with the pH 7.0 and
4.0 buffers. Wide variations can be caused by meter
malfunction or contaminated buffer solutions. After
the electrodes have been washed and blotted again,
the meter is ready for use. Insert the electrodes in
the extract obtained by one of the methods described
in the previous section, and a stable reading should
be obtained within 1 to 2 minutes. Remove the
electrode, wash with distilled water, blot, and store
in a small sample of buffer. Consistency is impor-
tant, because it allows the nursery operator to
compare pH readings over a period of time.
Generally, plants grow best in a medium having
a pH of 5.5 to 6.5, since pH influences availability of
nutrients in the medium solution. The pH range of
5.0 to 6.5 provides a compromise range for greatest
availability of the maximum number of essential ele-
ments. If pH is higher than desired, sulfur can be
added to lower the pH, but this must be done care-
fully since sulfur burns roots at relatively low con-
centrations. A pH lower than desired can be cor-
rected with the incorporation of dolomitic limestone.
The formulation and particle size of the lime deter-
mine its reaction rate. Dolomitic and agricultural
limestone react over a period of several weeks to
several months, and should be mixed with media for
best results. The smaller the particle size, the faster
the reaction. Media pH should be measured before
potting to determine appropriate rates of amend-
ments, and routine pH (at least monthly) determina-
tions are advised.

Potting Media Requirements

A good potting medium must anchor plants and
provide adequate nutrients, water, and air. Roots
without adequate air will grow poorly or die, regard-
less of how good other factors may be.

Aeration and Water-Holding Capacity
Growers who experiment with media need to be
able to check water-holding capacity and aeration of
each medium. Several published lists give the water-
holding capacities and air space of various growing
media. Such charts are useful; however, there are
many situations they do not and cannot cover. Due
to significant effects of the container (i.e. depth, total
volume, configuration), these determinations should
be made with the specific containers) used for the
crop. A simple procedure can be used for this that
costs little except time. Materials needed are a
measuring cup, masking tape, a pencil, the contain-
ers to be used, a bucket or pan, and a few containers
for water.

Measurement Procedures
Air space of a medium is the total volume of
pores filled with air after irrigation and drainage.
The water-holding capacity is the percent of the total
volume of the medium that is filled with water after
irrigation and drainage. When a medium is satur-
ated and allowed to drain, air replaces the volume of
water drained. Measuring the drainage water then
gives a quick measurement of drainable pore space
or air space. Steps in the procedures for determin-
ing air space and water-holding capacity are given
below. If a measurement of air space alone is
desired, there is no need to determine the volume of
water required to saturate the dry medium in step 3.
1. Measure the container volume. Secure tape on
the container drainage holes and fill with water to
within approximately 1/2 inch (13 mm) of the brim.
Mark this line with a pencil. Carefully measure the
volume of water by pouring it into a measuring cup.
This volume of water is the container volume to be
occupied by the medium.
2. Dry the container inside. Do not remove the
tape. Fill the container with dry medium to the "fill
line," marked in Step 1, using packing procedures as
when potting a plant.

3. Using a measuring cup, slowly add water to
the container and keep track of the volume of water
used. Wet the medium until it is saturated (a thin
film of free water is present on the surface). Some
dry media such as peat moss or pine bark are
difficult to wet. If a wetting agent is used in produc-
tion, then use a wetting agent at this time at the
recommended rate. Add small amounts of water
periodically as necessary to ensure complete satura-
tion. The volume of water used to saturate the
medium is the total pore space of the medium.
4. Loosen the tape on one drainage hole and
discard water that drains from the medium. This
initial drainage helps settle the medium as it would
in production.
5. Cover the drainage hole and resaturate the
medium with water. Adding water along only one
side of the container will minimize air pockets.
6. Place the container in a pan or bucket large
enough to collect all drainage water. Elevate the
container above the pan for complete drainage.
Remove the tape from the holes and collect the
water drained during a 2-hour period.
7. Measure the volume of water drained from the
container. Use the smallest units on the measuring
cup (millimeters, ounces, or teaspoons).
8. Calculate the water-holding capacity and the
percent air space by the following formula.

% air space =volume of drained water (step 7) x 100
container volume (step 1)

water holding capacity =
([total pore space (step 3) volume of drained
water (step 7)] X 100) + container volume (step 1)

9. It is advisable to take 3 to 5 container/medium
samples through the procedures at the same time
and average the calculated parameters.

Interpreting the Measurements
These procedures allow the evaluation of the
percent air space and water-holding capacity of par-
ticular media in the particular containers chosen for
the crop. Media with predominantly small pores
(small particles) tend to retain more water, and
consequently have less aeration, than a medium
having large pores (large particles). The ratio of
various media components and component particle
sizes must be adjusted to the specific container, plant
requirements, and other production practices of
individual growers.
Air space requirements for most greenhouse crops
range from 10 to 20 percent, with most bedding

plant media containing only 5 to 10 percent air space
after drainage. Water-holding capacities for these
media should be 40 to 50 percent. Epiphytic orchids,
ferns, bromeliads, and other moisture-sensitive plants
require more than 35 percent air space. Some
woody ornamentals grown outdoors may require
media with 25 percent air space to provide adequate
drainage during the rainy season in Florida. The
water-holding capacity of media in these production
systems should be 30 to 40 percent.

Measuring Light Intensity

Growers of ornamental plants, particularly foliage
and flowering plants, must be able to regulate the
light intensity received by crops if maximum plant
growth and acceptable quality are to be achieved.
Some nursery operators think they can visually
estimate light intensity in areas where shade-grown
crops are located and adjust shade levels based on
previous experience. Unfortunately, such judgments
and manipulations are frequently not accurate, and
substantial reductions in crop growth and quality are
sustained. Proper measurement and regulation of
light intensity can be done only through use of an
appropriate light meter. Since some nursery opera-
tors maintain plants in commercial, institutional, or
residential buildings, a meter should be sensitive to
light levels of 50-foot candles (ft-c) or less. Nursery
production light levels in greenhouses and shade-
houses will vary dramatically, depending on geogra-
phic location, season, time of day, type and condition
of structure cover, and weather. A meter that can
measure up to 10,000 ft-c is desirable.
The best type of light meter for practicing hor-
ticulturists is an incident light meter that reads
directly in ft-c or lux units. An incident meter is
pointed with the light-sensing cell toward the light
source as opposed to many photographic light meters
of the reflectance type that must be pointed toward
the subject to measure reflected light. A few inci-
dent-type meters used primarily for studio work have
conversion scales or factors for conversion to ft-c or
lux units. Techniques described for using cameras
with built-in meters to determine light intensity
should not be used, because they are awkward and
less accurate than incident meters. Table 3 lists
several sources of incident light meters that can be
used in nurseries, greenhouses, and indoors.

Photographic Records

Some nursery operators keep complete records of
crop production procedures, including pests and other

problems encountered. Record usefulness can be
enhanced with photographs that can be referred to
after a problem or situation has passed. Usually
color slide film (35 mm) or color print film is prefer-
red, since many problem symptoms involve plant
color change.
If the nursery operator plans to give illustrated
talks at trade meetings or have illustrated seminars
for employees, transparency film (slide film) is proba-
bly best. Color prints can be made from slides if
prints are also needed. Negative color film would be
the cheapest route if only color prints are desired,
and would result in higher quality color prints.
Proper camera selection will depend upon nursery
needs, photographer expertise and equipment money
available. A 35 mm, single-lens reflex camera
provides maximum flexibility. A camera equipped
with some type of macro-lens can be focused very
close to small plants or plant parts without the
addition of extension tubes, bellows, or portrait
lenses. The 110 or disk film format is adequate if
only general snapshots are desired and the need for
ultra closeups is not anticipated. Once a camera and
accessories have been selected, the equipment can be
purchased from a local camera store or discount mail

order supplier listed in most photography magazines.
Camera equipment should be stored in a clean, cool,
dry environment, and a protective case is desirable if
the camera is to be transported routinely.

Optical Aids

Damage resulting from physiological disorders,
mechanical damage, or damage from pests is often
obvious to the unaided eye, and no further inspection
is necessary to diagnose the cause. Injury symptoms
or pests on aerial portions of the plant or the root
system that are difficult to see must be magnified to
be studied.
A hand lens of approximately 10 to 20 power is
useful in diagnosing many plant problems. A binocu-
lar microscope with 20- to 80-power magnification
should prove useful if additional magnification is
required frequently (Figure 4). A small, high-inten-
sity lamp is useful for illumination of plant speci-
mens when using a hand lens or low power micro-
Some hand magnifiers come equipped with
battery-powered light sources, which are handy when

Table 3. Selected Incident light meters for use by ornamental horticulturists.

Areas where meters can be used*
Light intensity Greenhouse Name and address of
Meter and sensitivity range Outdoor and Building Relative manufacturer or
model (ft-c)** in Fla. shadehouse interior cost national distributor

General Electric 0-10,000 Winteronly + + Low General Electric Co.
(Model 214) Nela Park
Cleveland, OH 44112

Gossen 0-32,000 + + + Intermediate Berkeley Marketing Co.
(Luna-Pro) (conversion Gossen Division
scale) P.O. Box 1060
Woodside, NY 11377

Gossen 0-12,000 Fall and + + High Berkeley Marketing Co.
(Panlux) winter only Gossen Division
P.O. Box 1060
Woodside, NY 11377

Sekonic 0-1,250 Heavily + Intermediate Copal Corp. of America
(Model L-398) shaded 58-24 Queens Blvd.
greenhouse Woodside, NY 11377

Spectra 0-30,000 + + + Intermediate Photo Research
(Candela) 3000 N. Holiwood
Burbank, CA 91505
*+ = OK for use in indicated area,- = not for use in indicated area.
**Foot-candles x 10.76 =lux.

portability and relatively low magnification are
needed. A headband mounted magnifier may be
preferred in some situations where many specimens
are examined under field conditions, because it gives
the observer the use of both hands while working
(Figure 5). A partial listing of some optical aids and
their sources is provided in Table 4.

Binocular microscope
(20 to 80 X)

Table 4. A partial list of sources of optical aids for plant
problem diagnosis.


Type of optical aid


'x E ca '0 x

m a) ti
C4 E E E .
M X un,

Office supply stores X X
Laboratory supply firms including:
Fisher Scientific
7464 Chancellor Drive
P.O. Box 13430
Orlando, FL32809 X X
Baxter Scientific Products
1900 NW 97th Avenue
Miami, FL33172 X X
Biological supply firms including:
Carolina Biological Supply Co.
Burlington, NC 27215 X X
Forestry supply firms including:
Forestry Suppliers, Inc.
205 West Rankin Street
P.O. Box 8397
Jackson, MS 39284 X X X X

Plant Problem Referrals

Simple hand lens
(10 to 20 X)

Figure 4.

Headband mounted binocular
magnifier -

Figure 5.

Many of the day-to-day plant diagnostic activities
can be accomplished using the procedures and/or
equipment described in this publication. Occasional-
ly, more complex testing procedures or highly special-
ized professional advice from your county extension
office or a professional consultant is needed to avoid
economic losses. The following procedures may be
followed for referral of several categories of nursery
plant problems. Each diagnostic service has its own
sample information form and instructions for sample
collection and offers its own interpretation based
upon the procedures used. Maximum benefit from
the time and effort invested in samples can only be
realized when the instructions for the specific test
are followed and the form is completed with as much
detail as requested. Professionals at your county
extension office can assist with more details on
sample collection and preparation and interpreting
the results of diagnostic tests.

Suspected Disease Problems

Pathogen identification requires highly trained
personnel, specialized isolation and culturing techni-
ques, and a compound light microscope with a mag-
nification range of 100 to 1000 power. Unless a
nursery is large enough to have a plant pathologist,
required optical equipment, and related supplies for
pathogen detection, plant tissue suspected of harbor-
ing unidentified pathogens should be sent to a
diagnostic laboratory. Samples can be sent through
your county extension office to the Florida Extension
Plant Disease Clinic, Plant Pathology Department,
University of Florida. Each sample must be sub-
mitted with a completed "Plant Disease Diagnostic
Form" (IFAS form 2901), which can be obtained from
your county extension office along with additional
instructions for sample collection and handling.
Diagnostic results from the clinic are transmitted to
the local county extension office by electronic mail,
and this information is then passed on to the nur-
sery operator. There is no charge for this service.

Suspected Insect and Mite Damage

Submit suspected and unidentifiable pest or plant
samples showing pest damage to your county exten-
sion office. They have the required forms, vials, and
mailers for sending samples to the Extension En-
tomologist, Entomology Department, University of
Florida, Gainesville, FL 32611. Results of the
diagnosis are sent to the county extension office from
which the nursery operator is informed.
Insect identification can also be obtained through
the Division of Plant Industries (DPI) of the Florida
Department of Agriculture and Consumer Services.
A DPI inspector is assigned to periodically inspect
your nursery plants.

Suspected Parasitic Nematode Problems

Nursery operators should request one or more
"Nematode Sample Kits" from their county extension
office. Each kit contains instructions for sampling, a
data sheet, a sample box, and a mailer. Boxed sam-
ples are then sent by the nursery operator, with a
$8.00 payment per sample, to: Nematode Assay
Laboratory, Building 78, IFAS, University of Florida,
Gainesville, FL 32611-0611. Assay results are
mailed directly to the nursery operator. A copy of
these results is also sent to the county extension

Weed Sample Identification

Unidentified weed samples can be taken to the
county extension office where they will be sent with
a "Request for Plant Information Form" (IFAS form
3100) to the Herbarium, 209 Rolfs Hall, IFAS,
University of Florida, Gainesville, FL 32611-0322.
Identification information will be returned to the
county extension office by mail.

Plant Tissue Samples

Since the Florida Cooperative Extension Service
does not offer a leaf nutrient analysis service, it
would be advisable to work with a commercial
laboratory with staff who have experience with
nursery crops. A list of commercial laboratories in
Florida that routinely perform tissue analyses can be
obtained from your county extension office. Labora-
tories with experience and expertise in procedures
and the associated interpretation with nursery crops
should be selected.

Container Media Samples

If more information about the chemical status of
a potting medium than soluble salts and pH is
needed, sampling procedures and submission form
(IFAS form 2674) can be obtained from your county
extension office. Samples may be submitted through
the county extension office or mailed directly to the
Extension Soil Testing Laboratory at the address
provided on the sample submission form. The
"Container Media Test" includes the determination of
pH, electrical conductivity, N03, N, P, K, Ca, and
Mg for a cost of $6.00 per sample. Reports of
potting media tests are sent to the county extension
office and to the nursery operator by return mail.

Irrigation Water Samples

The Extension Soil Testing Laboratory also con-
ducts analyses of water for pH, electrical conduc-
tivity, Ca, Mg, Na, Fe, and Cl. Water samples
should be submitted to your county extension office
or mailed directly to the laboratory with a payment
of $7.00 per sample. Samples should be sent to the
Extension Soil Testing Laboratory with a completed
IFAS Form 2673-A, and the results of the test will
be sent to the nursery operator and the county
extension office by return mail. This test does not
determine if the water is safe for human consump-
tion. Bacteriological tests are available from the
county health department.

Gas Testing

The nursery atmosphere influences crop growth,
as does media fertility level, water quality, and other
factors. Few nurseries monitor air quality or modify
atmospheric parameters other than temperature
and/or humidity.
Crop damage has been reported when industrial
firms release air pollutants, such as sulfur dioxide or
hydrogen fluoride, that drift over crops and other
vegetation. This type of damage is difficult to diag-
nose, as it occurs infrequently and lasts for a rela-
tively short period of time.
Heating units in greenhouses occasionally burn
improperly due to poor maintenance, and produce
one or more by-products, including ethylene and/or
sulfur dioxide, which can injure plants. Concentra-
tions of gases suspected of causing plant damage
within a nursery can be tested with one or more gas
testing devices.
Mine Safety Appliances Company, Pittsburgh, PA,
15208 manufactures a gas testing kit that can be
used to test for more than 100 different gases, vapors
and mists, with the appropriate glass sampling tube,
filter, and reagent kit. Most gaseous pollutants en-
countered under greenhouse conditions require only
a glass detector tube designed for the specific gas
being investigated. Periodic characterization of gases
in greenhouse atmospheres is recommended if forced
air heating units are used. Ideally, heaters should be
on and greenhouse ventilators, or fan louvers, closed

for approximately 20 to 30 minutes before drawing
a sample with a gas testing device.

Temperature and Humidity Recorders

Temperature and humidity recorders inform
greenhouse managers of fluctuations in these condi-
tions over time. This information allows the manag-
er to make necessary adjustments in climate control
to optimize crop growth while minimizing energy
costs. Interactions between temperature and humid-
ity are extremely important, especially when critically
cold temperatures threaten crop plants.
Such environmental sensors and recorders are
usually positioned in the greenhouse, but chart
paper, calibration equipment and procedures, and file
storage for recorded data should be stored in the
nursery laboratory. Instruments can be purchased
that record both humidity and temperature or just
one of these parameters. Instrument sophistication
ranges from simple chart recorders to electronic
micro-processors that record the parameters at
multiple stations and may even automatically adjust
environmental control equipment.

Trade names of suppliers or equipment items men-
tioned in this publication are used because of known
availability. No endorsement of products is intended
nor is criticism of unnamed products implied.

Worksheet for calculations

director, in cooperation with the United States Department of Agriculture, publishes this information to further the purpose of the May 8 and June 30,
1914 Acts of Congress; and is authorized to provide research, educational information and other services only to individuals and institutions that
function without regard to race, color, sex, handicap or national origin. Single copies of extension publications (excluding 4-H and youth publications)
are available free to Florida residents from county extension offices. Information on bulk rates or copies for out-of-state purchasers is available from
C.M. Hinton, Publications Distribution Center, IFAS Building 664, Universityof Florida, Gainesville, Florida32611. Before publicizing this publication,
editors should contact this address to determine availability. Printed 11/90.

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