• TABLE OF CONTENTS
HIDE
 Copyright
 Nitrogen
 Phosphorus
 Potassium
 Calcium
 Magnesium
 Boron
 Copper
 Iron
 Manganese
 Zinc
 Results of fertilizer experime...






Group Title: Mimeo report - Gulf Coast Station - 58-2
Title: Fertilization of gladiolus
CITATION PAGE IMAGE ZOOMABLE PAGE TEXT
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00067646/00001
 Material Information
Title: Fertilization of gladiolus
Series Title: Gulf Coast Station mimeo report
Physical Description: 6 leaves. : ; 28 cm
Language: English
Creator: Woltz, S. S
Gulf Coast Experiment Station (Bradenton, Fla.)
Publisher: Gulf Coast Station
Place of Publication: Bradenton Fla
Publication Date: 1958
 Subjects
Subject: Gladiolus -- Fertilizers -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: S.S. Woltz.
General Note: Caption title.
General Note: "Note: This is a reprint from The Proceedings of the Florida State Horticultural Society, Vol. 69, pages 347-351, prepared for the information of gladiolus growers."
Funding: Florida Historical Agriculture and Rural Life
 Record Information
Bibliographic ID: UF00067646
Volume ID: VID00001
Source Institution: Marston Science Library, George A. Smathers Libraries, University of Florida
Holding Location: Florida Agricultural Experiment Station, Florida Cooperative Extension Service, Florida Department of Agriculture and Consumer Services, and the Engineering and Industrial Experiment Station; Institute for Food and Agricultural Services (IFAS), University of Florida
Rights Management: All rights reserved, Board of Trustees of the University of Florida
Resource Identifier: oclc - 71341398

Table of Contents
    Copyright
        Copyright
    Nitrogen
        Page 1
    Phosphorus
        Page 2
    Potassium
        Page 2
    Calcium
        Page 3
    Magnesium
        Page 3
    Boron
        Page 3
    Copper
        Page 4
    Iron
        Page 4
    Manganese
        Page 5
    Zinc
        Page 5
    Results of fertilizer experiments
        Page 5
        Page 6
Full Text





HISTORIC NOTE


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida




Gulf Coast Station Mimeo Report 58-2


FERTILIZATION OF GLADIOLUS

S. S. Woltz, Asst. Horticulturist

Note: This is a reprint from The Proceedings of the
Florida State Horticultural Society Vol. 69, pages 347 to 351,
prepared for the information of gladiolus growers.

Reports from various parts of the country indicate that gladiolus
fertilizer requirements vary a great deal with the particular soil and cli-
mate encountered. While it is true that other crop plants must also be fer-
tilized according to soil and climate, gladiolus differ from gross feeders
such as corn in that maximum flower yield and quality are obtained at a
lower level of fertilization and some soils require little or no fertilizer.
Still another difference is the sizeable reserve of inorganic and organic
nutrients present in large corms. Thus, in soil of good nutrient-supply-
ing capacity one does not see large responses from fertilizer applications.
In regions of light, sandy soil such as the Southern Atlantic and Gulf Coastal
Plains of the United States, it is necessary to fertilize gladiolus adequate-
ly to obtain optimum production of high quality spikes and corms. With
light soils and heavy rainfall it is necessary to fertilize frequently in
small doses. The response of gladiolus to fertilizer is oftentimes a de-
layed reaction and many effects will show up the second season due to the
superior quality of corms fertilized adequately.

Nutritional requirements of gladiolus vary depending on variety and
chemical composition and size of corms or cormels. Some varieties such as
Morning Kiss and Spotlight respond more to fertilizer than others such as Rosa
Van Lima and Elizabeth the Queen. Large corms require less fertilizer than
cormels and smaller corms due partly to the stored reserve and partly to
greater feeding capacity of the extensive root system produced by large corms.

Any condition that damages the root system seriously will increase
the need for fertilizer due to an impairment in the uptake from the soil
unless, of course, there is a luxury supply of nutrients in the soil. When
roots are damaged there is need for placement of fertilizer nearer the plant,
more frequent irrigation, and the use of foliar nutritional sprays. Factors
likely to cause root damage include mechanical pruning in cultivation, nema-
tode and fungus attack, water-logging of soil and chemical damage such as
salt injury.

The following section is devoted to a brief consideration of cer-
tain nutrient elements, discussed singly. Reference to nutrient require-
ments in terms of the amount to be found in plant tissues should be regarded
as approximate since the amounts required will vary somewhat depending on
nutritional balance and environmental factors.

Nitrogen

This element is the one most likely to produce yield responses in
gladiolus. Analysis of leaf samples fertilized in various ways indicates
that the leaves should contain on a dry weight basis 2.5 ro 3.0 percent
nitrogen or more for optimum yield. The effects of nitrogen deficiency
include a reduction in the number of florets per spike and number of spikes
per corm together with the customary pale green coloration of foliage found
in nitrogen deficiencies. Also,the utilization of oldkoymn food reserves
is hampered by lack of nitrogen. There is ample evidence that .excess nitro-
gen accelerates Fusarium corm rot and, in order to use high nitrogen levels
to obtain good yields it is necessary to have good preventive measures for

n\ ^ .-*'^







the control of Fusarium corm rot. Nitrogen is an element required in somewhat
greater amounts by small corms and cormels than by large corms.

The form in which nitrogen is supplied is important. Flower quality is
better when nitrogen is supplied partly as nitrate and partly as ammonium than
when the element is supplied entirely from either source. Care must be taken
with organic sources to assure that decomposition will take place and the
nitrogen will be utilized in time to benefit the crop. This is especially
important for applications made late in the growing season. In general, inor-
ganic nitrogen is preferred due to quick availability and low cost; however,
greater frequency of application is needed with inorganic than with organic
nitrogen sources.

Gladiolus are sometimes damaged by large amounts of ammonium nitro-
gen in the soil, especially when nitrate nitrogen is at a low level. Gladiolus
are adversely affected by calcium cyanamid in the soil under many conditions,
more so than many other plants. It is important when using calcium cyanamid
as a soil sterilant to allow ample time for the residual effects to disappear
before planting gladiolus.

Excess nitrogen, especially in the absence of adequate potassium and
calcium, is unfavorable to flower quality due to nutritional imbalance.

Phosphorus

The amount of phosphorus required by gladiolus is only about one-tenth
the nitrogen expressed in terms of foliar analysis. Thus, if the leaves con-
tain 0.3 to 0.4 percent phosphorus, it is unlikely that additional phosphorus
will increase yield. The symptoms of phosphorus deficiency are dark green fo-
liage and purple coloration in the lower leaves. It has been reported that
high levels of phosphorus increase the resistance to Fusarium corm rot. Phos-
phorus in the corm is readily utilized by the new plant and this source of
supply is very important. It is probable that the plant can take up enough
phosphorus early in the season to last the whole season, should the available
phosphorus level in the soil drop toward the end of the season. This element
is rather freely translocated throughout the plant and the new tissue is well
supplied with phosphorus from older tissue.

Phosphorus fixation in the soil is a perennial problem in areas of
clay-bearing soil having high iron and aluminum contents. This problem is
met by liming and proper placement of phosphorus-source materials. In sandy
soils of lower iron and aluminum contents such as are found in most regions
of Florida, the phosphorus problem is not so serious. In soils recently
brought into cultivation there is usually a deficiency, but with heavy appli-
cations of complete fertilizaers, a large reserve of available phosphorus
is soon built up. An exception is found when the soils are allowed to become
very acid (pH 4.5 for example) in which case phosphorus may be leached out by
rainfall. Thus, in Florida, after complete fertilizer has been applied to
the soil for about ten years there will usually be found sufficient phosphorus
to grow the crop for a number of years. Continued use of superphosphate in
the mixed fertilizer is then justified principally by the other nutrient ele-
ments present in ordinary superphosphate (calcium, sulfur, and trace elements),
together with the low cost of nitrogen from anmoniated superphosphate.

Potassium

Gladiolus require about 3 to 4 percent potassium in the leaves for
optimum growth. A lack of potassium results in a serious shortening of spike
stem-length together with a general yellowing of older leaves and a yellowing







the control of Fusarium corm rot. Nitrogen is an element required in somewhat
greater amounts by small corms and cormels than by large corms.

The form in which nitrogen is supplied is important. Flower quality is
better when nitrogen is supplied partly as nitrate and partly as ammonium than
when the element is supplied entirely from either source. Care must be taken
with organic sources to assure that decomposition will take place and the
nitrogen will be utilized in time to benefit the crop. This is especially
important for applications made late in the growing season. In general, inor-
ganic nitrogen is preferred due to quick availability and low cost; however,
greater frequency of application is needed with inorganic than with organic
nitrogen sources.

Gladiolus are sometimes damaged by large amounts of ammonium nitro-
gen in the soil, especially when nitrate nitrogen is at a low level. Gladiolus
are adversely affected by calcium cyanamid in the soil under many conditions,
more so than many other plants. It is important when using calcium cyanamid
as a soil sterilant to allow ample time for the residual effects to disappear
before planting gladiolus.

Excess nitrogen, especially in the absence of adequate potassium and
calcium, is unfavorable to flower quality due to nutritional imbalance.

Phosphorus

The amount of phosphorus required by gladiolus is only about one-tenth
the nitrogen expressed in terms of foliar analysis. Thus, if the leaves con-
tain 0.3 to 0.4 percent phosphorus, it is unlikely that additional phosphorus
will increase yield. The symptoms of phosphorus deficiency are dark green fo-
liage and purple coloration in the lower leaves. It has been reported that
high levels of phosphorus increase the resistance to Fusarium corm rot. Phos-
phorus in the corm is readily utilized by the new plant and this source of
supply is very important. It is probable that the plant can take up enough
phosphorus early in the season to last the whole season, should the available
phosphorus level in the soil drop toward the end of the season. This element
is rather freely translocated throughout the plant and the new tissue is well
supplied with phosphorus from older tissue.

Phosphorus fixation in the soil is a perennial problem in areas of
clay-bearing soil having high iron and aluminum contents. This problem is
met by liming and proper placement of phosphorus-source materials. In sandy
soils of lower iron and aluminum contents such as are found in most regions
of Florida, the phosphorus problem is not so serious. In soils recently
brought into cultivation there is usually a deficiency, but with heavy appli-
cations of complete fertilizaers, a large reserve of available phosphorus
is soon built up. An exception is found when the soils are allowed to become
very acid (pH 4.5 for example) in which case phosphorus may be leached out by
rainfall. Thus, in Florida, after complete fertilizer has been applied to
the soil for about ten years there will usually be found sufficient phosphorus
to grow the crop for a number of years. Continued use of superphosphate in
the mixed fertilizer is then justified principally by the other nutrient ele-
ments present in ordinary superphosphate (calcium, sulfur, and trace elements),
together with the low cost of nitrogen from anmoniated superphosphate.

Potassium

Gladiolus require about 3 to 4 percent potassium in the leaves for
optimum growth. A lack of potassium results in a serious shortening of spike
stem-length together with a general yellowing of older leaves and a yellowing





between the veins of younger leaves. In severe cases the older leaves show
marginal leaf burn. The number of florets per spike is reduced by potassium
deficiency, together with a delay in flowering time. Sulfate of potash is
preferred over muriate when irrigation water contains large amounts of the
chloride ion. Otherwise there is no indication of any great difference be-
tween these sources.

Calcium

Calcium is important in producing quality gladiolus flowers. A mild
deficiency of calcium will result in the disorder known as "topple" which re-
fers to the breaking over of gladiolus in the vase after most of the florets
have opened. More severe calcium deficiency causes a condition similar to bud-
rot encountered in the commercial production of gladiolus. Affected florets do
not open normally; petals tend to cup inward and there may be a break-down of
petal tissue with water-soaking apparent. Only in the most severe deficiencies
are leaves affected. Calcium deficiency of leaves results in their emerging
from sheathing leaves in a soft, gelatinous condition initially light colored,
but later turning brown. Some horizontal cracking of leaves is encountered.

To insure against calcium deficiency, spikes should contain, on the
dry weight basis, 0.2 or preferably 0.3 percent calcium. In order to accom-
plish this, the soil must be well supplied with available calcium from sources
such as gypsum lime and ordinary superphosphate. Calcium is not translocated
freely from leaves to spike and it is therefore necessary to have the element
amply available during the time the spike is rapidly forming. Triple super-
phosphate does not contain gypsum (calcium sulfate) which is present in ordi-
nary superphosphate to the extent of about 50 percent. To further insure a-
gainst calcium deficiency, the grower may side-dress with calcium nitrate
which contains soluble calcium or he may spray two or three times between
spike emergence and flowering with four pounds of calcium nitrate per one
hundred gallons.

Magnesium

Although magnesium plays a central structural part in the chlorophyll
molecule, the need for this element by gladiolus is not for large amounts.
Leaves to be normal should contain about 0.2 to 0.4 percent magnesium. Symp-
toms of magnesium deficiency are a yellowing between the veins, first seen
in the older leaves. With magnesium deficiency there is a delay in flowering,
although not as much as with potassium deficiency.

It is important in furnishing magnesium to gladiolus to avoid excessive
supplies since this element interferes with calcium nutrition when used in a-
mounts greater than required normally. Adequate magnesium is usually obtained
from dolomitic limestone or by the inclusion of 1 percent water-soluble MgO
in mixed fertilizer. Irrigation water may contain 100 ppm or more of magne-
sium which should neet the needs of the crop if applied in sufficient volume
over the growing season.

Boron

Gladiolus are relatively tolerant to boron and have a moderate require-
ment for the element. Deficiencies of boron cause a horizontal cracking begin-
ning at the margin of the leaf and extending inward toward the midrib. In some
varieties, such as Hopman's Glory, there is less cracking of leaves but there
are translucent areas between the veins and in some cases the veins grow to-
gether. The mature leaves should contain more than 15 ppm boron in order not
to be deficient. Leaves are generally deficient if there is as little as 10





between the veins of younger leaves. In severe cases the older leaves show
marginal leaf burn. The number of florets per spike is reduced by potassium
deficiency, together with a delay in flowering time. Sulfate of potash is
preferred over muriate when irrigation water contains large amounts of the
chloride ion. Otherwise there is no indication of any great difference be-
tween these sources.

Calcium

Calcium is important in producing quality gladiolus flowers. A mild
deficiency of calcium will result in the disorder known as "topple" which re-
fers to the breaking over of gladiolus in the vase after most of the florets
have opened. More severe calcium deficiency causes a condition similar to bud-
rot encountered in the commercial production of gladiolus. Affected florets do
not open normally; petals tend to cup inward and there may be a break-down of
petal tissue with water-soaking apparent. Only in the most severe deficiencies
are leaves affected. Calcium deficiency of leaves results in their emerging
from sheathing leaves in a soft, gelatinous condition initially light colored,
but later turning brown. Some horizontal cracking of leaves is encountered.

To insure against calcium deficiency, spikes should contain, on the
dry weight basis, 0.2 or preferably 0.3 percent calcium. In order to accom-
plish this, the soil must be well supplied with available calcium from sources
such as gypsum lime and ordinary superphosphate. Calcium is not translocated
freely from leaves to spike and it is therefore necessary to have the element
amply available during the time the spike is rapidly forming. Triple super-
phosphate does not contain gypsum (calcium sulfate) which is present in ordi-
nary superphosphate to the extent of about 50 percent. To further insure a-
gainst calcium deficiency, the grower may side-dress with calcium nitrate
which contains soluble calcium or he may spray two or three times between
spike emergence and flowering with four pounds of calcium nitrate per one
hundred gallons.

Magnesium

Although magnesium plays a central structural part in the chlorophyll
molecule, the need for this element by gladiolus is not for large amounts.
Leaves to be normal should contain about 0.2 to 0.4 percent magnesium. Symp-
toms of magnesium deficiency are a yellowing between the veins, first seen
in the older leaves. With magnesium deficiency there is a delay in flowering,
although not as much as with potassium deficiency.

It is important in furnishing magnesium to gladiolus to avoid excessive
supplies since this element interferes with calcium nutrition when used in a-
mounts greater than required normally. Adequate magnesium is usually obtained
from dolomitic limestone or by the inclusion of 1 percent water-soluble MgO
in mixed fertilizer. Irrigation water may contain 100 ppm or more of magne-
sium which should neet the needs of the crop if applied in sufficient volume
over the growing season.

Boron

Gladiolus are relatively tolerant to boron and have a moderate require-
ment for the element. Deficiencies of boron cause a horizontal cracking begin-
ning at the margin of the leaf and extending inward toward the midrib. In some
varieties, such as Hopman's Glory, there is less cracking of leaves but there
are translucent areas between the veins and in some cases the veins grow to-
gether. The mature leaves should contain more than 15 ppm boron in order not
to be deficient. Leaves are generally deficient if there is as little as 10





between the veins of younger leaves. In severe cases the older leaves show
marginal leaf burn. The number of florets per spike is reduced by potassium
deficiency, together with a delay in flowering time. Sulfate of potash is
preferred over muriate when irrigation water contains large amounts of the
chloride ion. Otherwise there is no indication of any great difference be-
tween these sources.

Calcium

Calcium is important in producing quality gladiolus flowers. A mild
deficiency of calcium will result in the disorder known as "topple" which re-
fers to the breaking over of gladiolus in the vase after most of the florets
have opened. More severe calcium deficiency causes a condition similar to bud-
rot encountered in the commercial production of gladiolus. Affected florets do
not open normally; petals tend to cup inward and there may be a break-down of
petal tissue with water-soaking apparent. Only in the most severe deficiencies
are leaves affected. Calcium deficiency of leaves results in their emerging
from sheathing leaves in a soft, gelatinous condition initially light colored,
but later turning brown. Some horizontal cracking of leaves is encountered.

To insure against calcium deficiency, spikes should contain, on the
dry weight basis, 0.2 or preferably 0.3 percent calcium. In order to accom-
plish this, the soil must be well supplied with available calcium from sources
such as gypsum lime and ordinary superphosphate. Calcium is not translocated
freely from leaves to spike and it is therefore necessary to have the element
amply available during the time the spike is rapidly forming. Triple super-
phosphate does not contain gypsum (calcium sulfate) which is present in ordi-
nary superphosphate to the extent of about 50 percent. To further insure a-
gainst calcium deficiency, the grower may side-dress with calcium nitrate
which contains soluble calcium or he may spray two or three times between
spike emergence and flowering with four pounds of calcium nitrate per one
hundred gallons.

Magnesium

Although magnesium plays a central structural part in the chlorophyll
molecule, the need for this element by gladiolus is not for large amounts.
Leaves to be normal should contain about 0.2 to 0.4 percent magnesium. Symp-
toms of magnesium deficiency are a yellowing between the veins, first seen
in the older leaves. With magnesium deficiency there is a delay in flowering,
although not as much as with potassium deficiency.

It is important in furnishing magnesium to gladiolus to avoid excessive
supplies since this element interferes with calcium nutrition when used in a-
mounts greater than required normally. Adequate magnesium is usually obtained
from dolomitic limestone or by the inclusion of 1 percent water-soluble MgO
in mixed fertilizer. Irrigation water may contain 100 ppm or more of magne-
sium which should neet the needs of the crop if applied in sufficient volume
over the growing season.

Boron

Gladiolus are relatively tolerant to boron and have a moderate require-
ment for the element. Deficiencies of boron cause a horizontal cracking begin-
ning at the margin of the leaf and extending inward toward the midrib. In some
varieties, such as Hopman's Glory, there is less cracking of leaves but there
are translucent areas between the veins and in some cases the veins grow to-
gether. The mature leaves should contain more than 15 ppm boron in order not
to be deficient. Leaves are generally deficient if there is as little as 10







ppm boron. Boron toxicity, expressed as a burn of the margins of older leaves,
is encountered when the boron content exceeds about 200 ppm. The toxicity is
increasingly serious and affects younger leaves when the boron content of older
leaves rises to 400 ppm or more.

Boron is generally furnished to gladiolus in areas of possible defi-
ciency as borax. There are new boron sources, however, that are of interest
due to their slower rates of solubility which have the advantage of reduced
toxicity while still furnishing adequate boron over a longer period of time.
These sources are Colemanite, a calcium borate compound whose solubility is
dependent partly on the fineness of grinding, and a less soluble material,
borosilicate, the latter being of variable composition.

Copper

Copper deficiency is expressed as a wilting of leaves and softness of
spikes. Some varieties, such as Valeria, are more susceptible. The deficien-
cy is found principally, in Florida, on new agricultural land. Preventive
treatment involves broadcasting twenty pounds or more, depending on soil type,
of copper sulfate per acre. A small amount may be included in the mixed fer-
tilizer as well. The copper level in deficient leaves has not been deter-
mined.

Copper toxicity is a problem often encountered on older agricultural
soils in Florida where the element has accumulated from past applications.
Most of the copper applied persists in the soil for many years due to the low
solubility of the various copper compounds formed. Toxicity of copper is ex-
pressed first as root damage and second as copper induced iron chlorosis of
the leaves. Induced iron deficiency generally shows up at about the four or
five leaf stage and, if not corrected, all later leaves and the spikes may
be quite yellowish or cream-colored. In the incipient stages the yellowing
is apparent only between the veins. Copper toxicity to the roots is reduced
by liming to a pH of about 6.5. The correction of iron deficiency in leaves
will be discussed under the section on iron.

Iron

Iron deficiency is manifested first by a yellowing between the veins
of new leaves and as the deficiency becomes more severe, by a general yellow-
ing of leaves. The color of florets of June Bells variety is affected, tend-
ing to be cream-colored rather than the usual white. Total iron content of
leaves is not a good guide to a deficiency since much of the iron in the plant
may be insoluble and not usable. Iron deficiency is more often due to compli-
cating factors instead of a simple lack of iron. High soil pH and excessively
high levels of heavy metals such as copper, manganese and zinc are the most
common causes.

The correction of iron deficiency is frequently difficult. The quick-
est method for soil application is the sidedressing of twenty pounds of che-
lated iron concentrate per acre in a manner that will make it quickly avail-
able. Single ..applicationsoffoliar sprays are not completely effective since
the iron taken up from spray droplets is not readily distributed but leaves
a pattern of green on a yellow background corresponding to the spray residue.
Repeated spraying with iron oxalate at two pounds per hundred gallons will
green up the foliage fairly well. Where leaves are damaged physically or ex-
cess spray residues accumulate unevenly in spots, it is possible to get black
blotches on the leaves, especially with Morning Kiss variety.







ppm boron. Boron toxicity, expressed as a burn of the margins of older leaves,
is encountered when the boron content exceeds about 200 ppm. The toxicity is
increasingly serious and affects younger leaves when the boron content of older
leaves rises to 400 ppm or more.

Boron is generally furnished to gladiolus in areas of possible defi-
ciency as borax. There are new boron sources, however, that are of interest
due to their slower rates of solubility which have the advantage of reduced
toxicity while still furnishing adequate boron over a longer period of time.
These sources are Colemanite, a calcium borate compound whose solubility is
dependent partly on the fineness of grinding, and a less soluble material,
borosilicate, the latter being of variable composition.

Copper

Copper deficiency is expressed as a wilting of leaves and softness of
spikes. Some varieties, such as Valeria, are more susceptible. The deficien-
cy is found principally, in Florida, on new agricultural land. Preventive
treatment involves broadcasting twenty pounds or more, depending on soil type,
of copper sulfate per acre. A small amount may be included in the mixed fer-
tilizer as well. The copper level in deficient leaves has not been deter-
mined.

Copper toxicity is a problem often encountered on older agricultural
soils in Florida where the element has accumulated from past applications.
Most of the copper applied persists in the soil for many years due to the low
solubility of the various copper compounds formed. Toxicity of copper is ex-
pressed first as root damage and second as copper induced iron chlorosis of
the leaves. Induced iron deficiency generally shows up at about the four or
five leaf stage and, if not corrected, all later leaves and the spikes may
be quite yellowish or cream-colored. In the incipient stages the yellowing
is apparent only between the veins. Copper toxicity to the roots is reduced
by liming to a pH of about 6.5. The correction of iron deficiency in leaves
will be discussed under the section on iron.

Iron

Iron deficiency is manifested first by a yellowing between the veins
of new leaves and as the deficiency becomes more severe, by a general yellow-
ing of leaves. The color of florets of June Bells variety is affected, tend-
ing to be cream-colored rather than the usual white. Total iron content of
leaves is not a good guide to a deficiency since much of the iron in the plant
may be insoluble and not usable. Iron deficiency is more often due to compli-
cating factors instead of a simple lack of iron. High soil pH and excessively
high levels of heavy metals such as copper, manganese and zinc are the most
common causes.

The correction of iron deficiency is frequently difficult. The quick-
est method for soil application is the sidedressing of twenty pounds of che-
lated iron concentrate per acre in a manner that will make it quickly avail-
able. Single ..applicationsoffoliar sprays are not completely effective since
the iron taken up from spray droplets is not readily distributed but leaves
a pattern of green on a yellow background corresponding to the spray residue.
Repeated spraying with iron oxalate at two pounds per hundred gallons will
green up the foliage fairly well. Where leaves are damaged physically or ex-
cess spray residues accumulate unevenly in spots, it is possible to get black
blotches on the leaves, especially with Morning Kiss variety.






Manganese

Manganese deficiency is evidenced by a yellowing between the veins of
the newer leaves. The principal cause of manganese deficiency is the poor
availability associated with high soil pH. Manganese deficiency is not often
encountered in gladiolus in Florida. Preventive measures include the use of
a small amount of manganous sulfate in mixed fertilizers and spraying with
maneb fungicide which contains manganese.

Zinc

Zinc deficiency has not been recognized in gladiolus in Florida. This
is probably due to the common use of the zinc-containing fungicide, zineb.

Zinc availability is greatly decreased by neutral or slightly alkaline
soil conditions. When growing gladiolus on such soil, one would be well-ad-
vised to take precautions to furnish zinc either by soil applications or pref-
erably by spraying in order to guard against a deficiency of the element.

Results of Fertilizer Experiments

The results of two three-season experiments with gladiolus at the
Gulf Coast Experiment Station are summarized in the following tables. In
Table 1 are given the results for one experiment involving Rosa Van Lima and
June Bells varieties. Corms were obtained from Holland, Rosa Van Lima being
size No. 3 and June Bells size No. 5. Data are totals for three seasons.
The Flower Production Index which is a measure of economic value is obtained
by giving C grade flowers two points and increasing by one point credit per
grade up to seven for the Extra Fancy grade. At the end of the first and
second season, after data were taken, corms from the four replicates of each
treatment were mixed and a standard number, usually 50 corms, was counted
out for each plot the following season and the remainder were discarded.
Fertilizer applications were made in four equal doses.

Table 1. Flower and Corm Production Data Combined for
June Bells and Rosa Van Lima with Various
Fertilizer Treatments,
Totals for Three Seasons, 1954-55.

No. of Flower Produc- No. of Weight of
Treatment Flowers tion Index Corms Corms (Lbs.)
No fertilizer 660 1424 1264 67.1
1000 Ibs. 4-8-8 713 1667 1333 78.0
2000 lbs. 4-8-8 823 2124 1268 82.6
2000 Ibs. 8-8-8 945 2323 1376 103.8
2000 Ibs. 16-8-8 927 2577 1359 98.8
2000 1bs. 4-8-16 897 2339 1329 97.1
2000 Ibs. 8-8-16 1068 2886 1319 113.6

Differences required for
statistical significance
at odds of 19:1 99 330 (Undetermined) 11.5


Table 2 presents flower and corm data for Picardy and Valeria. Vale- I
ria corms of flowering size were obtained from a commercial grower. Picardy
corms of planting stock size, No. 4 to' No. 6, came from stock grown at the
Gulf Coast Experiment Station.






Manganese

Manganese deficiency is evidenced by a yellowing between the veins of
the newer leaves. The principal cause of manganese deficiency is the poor
availability associated with high soil pH. Manganese deficiency is not often
encountered in gladiolus in Florida. Preventive measures include the use of
a small amount of manganous sulfate in mixed fertilizers and spraying with
maneb fungicide which contains manganese.

Zinc

Zinc deficiency has not been recognized in gladiolus in Florida. This
is probably due to the common use of the zinc-containing fungicide, zineb.

Zinc availability is greatly decreased by neutral or slightly alkaline
soil conditions. When growing gladiolus on such soil, one would be well-ad-
vised to take precautions to furnish zinc either by soil applications or pref-
erably by spraying in order to guard against a deficiency of the element.

Results of Fertilizer Experiments

The results of two three-season experiments with gladiolus at the
Gulf Coast Experiment Station are summarized in the following tables. In
Table 1 are given the results for one experiment involving Rosa Van Lima and
June Bells varieties. Corms were obtained from Holland, Rosa Van Lima being
size No. 3 and June Bells size No. 5. Data are totals for three seasons.
The Flower Production Index which is a measure of economic value is obtained
by giving C grade flowers two points and increasing by one point credit per
grade up to seven for the Extra Fancy grade. At the end of the first and
second season, after data were taken, corms from the four replicates of each
treatment were mixed and a standard number, usually 50 corms, was counted
out for each plot the following season and the remainder were discarded.
Fertilizer applications were made in four equal doses.

Table 1. Flower and Corm Production Data Combined for
June Bells and Rosa Van Lima with Various
Fertilizer Treatments,
Totals for Three Seasons, 1954-55.

No. of Flower Produc- No. of Weight of
Treatment Flowers tion Index Corms Corms (Lbs.)
No fertilizer 660 1424 1264 67.1
1000 Ibs. 4-8-8 713 1667 1333 78.0
2000 lbs. 4-8-8 823 2124 1268 82.6
2000 Ibs. 8-8-8 945 2323 1376 103.8
2000 Ibs. 16-8-8 927 2577 1359 98.8
2000 1bs. 4-8-16 897 2339 1329 97.1
2000 Ibs. 8-8-16 1068 2886 1319 113.6

Differences required for
statistical significance
at odds of 19:1 99 330 (Undetermined) 11.5


Table 2 presents flower and corm data for Picardy and Valeria. Vale- I
ria corms of flowering size were obtained from a commercial grower. Picardy
corms of planting stock size, No. 4 to' No. 6, came from stock grown at the
Gulf Coast Experiment Station.






Manganese

Manganese deficiency is evidenced by a yellowing between the veins of
the newer leaves. The principal cause of manganese deficiency is the poor
availability associated with high soil pH. Manganese deficiency is not often
encountered in gladiolus in Florida. Preventive measures include the use of
a small amount of manganous sulfate in mixed fertilizers and spraying with
maneb fungicide which contains manganese.

Zinc

Zinc deficiency has not been recognized in gladiolus in Florida. This
is probably due to the common use of the zinc-containing fungicide, zineb.

Zinc availability is greatly decreased by neutral or slightly alkaline
soil conditions. When growing gladiolus on such soil, one would be well-ad-
vised to take precautions to furnish zinc either by soil applications or pref-
erably by spraying in order to guard against a deficiency of the element.

Results of Fertilizer Experiments

The results of two three-season experiments with gladiolus at the
Gulf Coast Experiment Station are summarized in the following tables. In
Table 1 are given the results for one experiment involving Rosa Van Lima and
June Bells varieties. Corms were obtained from Holland, Rosa Van Lima being
size No. 3 and June Bells size No. 5. Data are totals for three seasons.
The Flower Production Index which is a measure of economic value is obtained
by giving C grade flowers two points and increasing by one point credit per
grade up to seven for the Extra Fancy grade. At the end of the first and
second season, after data were taken, corms from the four replicates of each
treatment were mixed and a standard number, usually 50 corms, was counted
out for each plot the following season and the remainder were discarded.
Fertilizer applications were made in four equal doses.

Table 1. Flower and Corm Production Data Combined for
June Bells and Rosa Van Lima with Various
Fertilizer Treatments,
Totals for Three Seasons, 1954-55.

No. of Flower Produc- No. of Weight of
Treatment Flowers tion Index Corms Corms (Lbs.)
No fertilizer 660 1424 1264 67.1
1000 Ibs. 4-8-8 713 1667 1333 78.0
2000 lbs. 4-8-8 823 2124 1268 82.6
2000 Ibs. 8-8-8 945 2323 1376 103.8
2000 Ibs. 16-8-8 927 2577 1359 98.8
2000 1bs. 4-8-16 897 2339 1329 97.1
2000 Ibs. 8-8-16 1068 2886 1319 113.6

Differences required for
statistical significance
at odds of 19:1 99 330 (Undetermined) 11.5


Table 2 presents flower and corm data for Picardy and Valeria. Vale- I
ria corms of flowering size were obtained from a commercial grower. Picardy
corms of planting stock size, No. 4 to' No. 6, came from stock grown at the
Gulf Coast Experiment Station.







A greater response to nitrogen was found for the three season period
with Rosa Van Lima and June Bells (Table 1) than with Picardy and Valeria
(Table 2). This is believed to be due in part to a higher incidence of Fu-
sarium corm rot in the latter two varieties that prevented maximum response
to nitrogen. The application of as much as eighty pounds of nitrogen per
acre during the growing season will generally meet the requirements of large,
flowering-size corms if leaching losses are not excessive and the root system
is normal. If roots are damaged by disease, nematodes or water, or if leach-
ing losses are heavy, a response will frequently be obtained to greater a-
mounts. Small corms and cormels having less stored nitrogen and less exten-
sive root systems will generally benefit from the application of up to 160
pounds of nitrogen per acre. Another factor increasing the total need of
small corms and cormels for nitrogen is the fact that their growing period
is longer.

Table 2. Flower and Corm Production Data Combined for
Picardy and Valeria with Various Fertilizer Treatments,
Totals for Three Seasons, 1954-56.

No. of Flower Produc- No. of Weight of
Treatment Flowers tion Index Corms Corms (Lbs.)
No fertilizer 887 3267 1560 142.9
1000 Ibs. 4-8-8 1072 4589 1655 178.1
2000 lbs. 4-8-8 1195 5532 1650 188.4
2000 lbs. 8-8-8 1184 5897 1674 189.9
2000 Ibs. 16-8-8 1188 5592 1561 181.0
2000 lbs. 4-8-16 1124 5334 1521 170.6

Difference Required
for statistical sig-
nificance at odds
of 19:1 84 658 (Undetermined) 11.5

Potash requirements for gladiolus generally can be met by applying
from 160 to 240 pounds K20 per acre during the growing season. As with ni-
trogen, the potash requirement depends on soil, rainfall, and the condition
of the root system. The response of small corms and cormels to variations
in potash level was not as marked as with nitrogen. This is due possibly to
the levels chosen for comparison.

A point of considerable interest in Table 1 is that when nitrogen was
furnished at the rate of 160 pounds per acre, beneficial results were obtained
in terms of flower production index by increasing potash from 160 to 320
pounds per acre. When nitrogen was held at the level of 80 pounds per acre
and potash increased from 160 to 320 pounds, there was no benefit in terms
of flower production.






Sept. 1957
300 copies




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