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Group Title: Research report - Bradenton Agricultural Research & Education Center - GC-1973-7
Title: Tomato fusarium wilt control by adjustments in soil fertility
CITATION PAGE IMAGE ZOOMABLE PAGE TEXT
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Permanent Link: http://ufdc.ufl.edu/UF00067683/00001
 Material Information
Title: Tomato fusarium wilt control by adjustments in soil fertility a systematic approach to pathogen starvation
Series Title: Bradenton AREC research report
Physical Description: 4 leaves : ; 28 cm.
Language: English
Creator: Woltz, S. S
Jones, J. P ( John Paul ), 1932-
Agricultural Research & Education Center (Bradenton, Fla.)
Publisher: Agricultural Research & Education Center, IFAS, University of Florida
Place of Publication: Bradenton Fla
Publication Date: 1973
 Subjects
Subject: Tomatoes -- Diseases and pests -- Control -- Florida   ( lcsh )
Tomatoes -- Soils -- Florida   ( lcsh )
Fusarium diseases of plants -- Control -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: S.S. Woltz and John Paul Jones.
General Note: Caption title.
General Note: "May 1973."
Funding: Florida Historical Agriculture and Rural Life
 Record Information
Bibliographic ID: UF00067683
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 - 71843403

Table of Contents
    Copyright
        Copyright
    Introduction
        Page 1
        Page 2
    Tomato fusarium wilt control by adjustments in soil fertiilty: A systematic approach to pathogen starvation
        Page 1
    Summary
        Page 3
        Page 4
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







) AGRICULTURAL RESEARCH & EDUI AT tMEJEkIBRARY
3 6 IFAS, University of F orida
C ,S-, -7 Bradenton, Floria JL 13 i73

Bradenton AREC Research Report GC-1973-7 May 1973
I.F.A.S. Univ. of Florida
TOMATO FUSARIUM WILT CONTROL BY ADJUS ETSINSOIL FEILT."
A SYSTEMATIC APPROACH TO PATHOGEN STARVATION

S. S. Woltz and John Paul Jones


A study has been in progress for some years on the nutritional requirements
and responses of the tomato Fusarium wilt pathogen for growth, sporulation and
virulence. The purpose has been to determine what chemical factors in the coil-
host environment may be adjusted to retard the proliferation and disease-producing
capacity of soil-borne race 2 tomato Fusarium. All the work has been related to
tomato culture on light, sandy soils.

Since these soils are low in native nutrients, the methods of fertilization
and liming may be manipulated to retard growth of Fucarium and to reduce the inci-
dence and severity of disease. Fusariium requires most of the same nutrients to
grow in the soil as do tomato plants. There are, however, important differences
in the responses to sources and amounts of nutrients available. While the tomato
may explore a large portion of the topsoil with a fairly extensive root system,
Fusarium growing units are limited to their microenvircnment. If the soil infes-
tation level of Fusarium is low, the rate of proliferation and disease-production
may be limited by using localized fertilizer placement to feed tomatoes without
making fertilizer nutrients available throughout the topsoil. Thus, the systematic
evaluation of Fusarium vs. tomato nutrient requirements must emphasize differences
that may be found, to keep Fusarium contaminant propagules in a state of starvation.

Race 2 tomato wilt Fusarium was grown in various artificial media by varied
cultural procedures to learn which chemical elements are needed and in what amounts.
The fungus was found to be dependent on any one of various carbon sources tested
but did not require calcium or boron, in agreement with the literature published
on other Fusaria. Race 2 Fusarium requires a total of 12 nutrient chemical elements
while tomato requires 15. These elements are widespread throughout the environment,
especially in soils and water but the amounts present may be exceedingly small cr
they may be locked in minerals, organic matter, or may be present in an insoluble
form. The procedure contemplated for a systematic establishment of desirable soil
nutrient regimes, therefore, involves the sw-ftineg cf the nutrient balance to a
situation that will arrest the major part of the growth and pathogenic activities
of Fusarium. A model system would retard Fusarium by causing deficiencies, excesses
or nutritional imbalances. Attempts to induce toxicity by excesses of common
chemical elements were not successful on a practical basis because of the relative
tolerance of Fusarium.

Fusarium (race 2) was cultured in artificial liquid media containing various
amounts of the micronutrient elements. Deficiencies of copper, iron, manganese,
molybdenum or zinc individually reduced growth and sporulation. When Manapal
seedlings were inoculated with race 2 FusarJum cultured cn Pmedia sdficient in
molybdenum or zinc, there was considerably ler. disease than fron incculum grown
with optimal zinc and molybdenum. The response of Fuserium to iron, manganese
and zinc in liquid cultures was very clear-cut. Amounts increased stepwise above










those usually found in the soil solution in tomato culture were increasingly bene-
ficial to growth and spore production, whereas concentrations below average inhibi-
ted Fusarium growth and sporulation. This indicated that manipulation of these
elements in soil management might control Fusarium wilt of tomato or at least avoid
luxury feeding of the pathogen and avoid an aggravation of disease severity.

A series of soil-culture experiments was undertaken with the tomato Fusarium
wilt problem wherein virgin Leon fine sand was amended with various amounts of
iron, manganese and zinc. The micronutrients were derived from fertilizer sources
of varying degrees of availability including sulfate compounds, chelates and ligno-
sulfates. Availability of micronutrients to Fusarium was reduced by liming soils
to approach neutrality or in some treatments to pH values of 7.5 or slightly higher.
Soil pH was also controlled by varying the proportion of nitrogen supplied by
nitrate vs. ammonium nitrogen. High percentages of nitrate raised soil pH while
high percentages of ammonium lowered pH. Findings from numerous experiments indi-
cated that liming to pH 6.8-7.5 reduced the incidence and severity of tomato Fusar-
ium wilt if supplemental soil applications of iron, magkanese and zinc to tomato
plants were avoided. The use of predominantly nitrate-nitrogen also elevated soil
pH and reduced disease. When soils were amended with these micronutrients singly
or in various combinations, the beneficial effects of:,H elevation'were reversed
to a significant degree but the benefit was not completely lost. Increase in soil
pH also reduces availability of other essential elements to Fusarium, especially
phosphorus and magnesium. Supplemental applications of superphosphate (above re-
quired amounts) to tomato field plots increased disease. Fusarium growth, sporu-
lation and virulence were increased stepwise with increasing amounts of available
magnesium supplied above deficiency levels.

Biological control is also a factor in the beneficial effect of liming and
other procedures that may be effective in Fusarium control by elevation of soil
pH. Bacteria and actinomycete microorganism populations are generally favored by
elevated soil pH values but the populations are suppressed by acid soil reactions.
Specific bacteria and actinomycetes prevented Fusarium spore germination and vege-
tative growth on agar plates presumably by means of toxic compounds produced by
the microorganism colonies. Zones of Fusarium inhibition extended beyond the
boundaries of the inhibitory colonies. Competition is also likely whereby the bac-
teria and actinomycetes remove organic and inorganic nutrients from the soil solu-
tion and limit the growth and disease-producing capacity of the Fusarium. In acid
soil (near pH 5.5), Fusarium has much less competition from this source. If nutri-
ents were available throughout the topsoil in a moderately acid environment, Fusar-
ium would be able to proliferate and constitute a serious production problem. Path-
ogenic Fusarium inadvertently brought into a field having low pH and high general
fertility with adequate fresh organic matter could easily establish a disease-
producing population.

Fusarium grown in liquid culture on ammonium-nitrogen was more virulent than
inoculum produced on nitrate-nitrogen. Tomato seedlings fertilized mainly with
nitrate-nitrogen were more resistant to Fusarium root inoculation than seedlings
grown primarily with ammonium-nitrogen. The overall effect of nitrogen source'
was related to pH change since greater acidity of soil was associated with greater
incidence and severity of disease. When various nitrate:ammonium ratios were com-
pared at different levels of liming, it was found that the usual disease preventive
effects of very high pH (7.5) were reversed by the use of all-ammonium nitrogen
applied to soil weekly. It is common practice, however, to supply a portion of
nitrogen fertilizer in the nitrate form; this practice can be beneficial in re-
tarding Fusarium wilt.







) AGRICULTURAL RESEARCH & EDUI AT tMEJEkIBRARY
3 6 IFAS, University of F orida
C ,S-, -7 Bradenton, Floria JL 13 i73

Bradenton AREC Research Report GC-1973-7 May 1973
I.F.A.S. Univ. of Florida
TOMATO FUSARIUM WILT CONTROL BY ADJUS ETSINSOIL FEILT."
A SYSTEMATIC APPROACH TO PATHOGEN STARVATION

S. S. Woltz and John Paul Jones


A study has been in progress for some years on the nutritional requirements
and responses of the tomato Fusarium wilt pathogen for growth, sporulation and
virulence. The purpose has been to determine what chemical factors in the coil-
host environment may be adjusted to retard the proliferation and disease-producing
capacity of soil-borne race 2 tomato Fusarium. All the work has been related to
tomato culture on light, sandy soils.

Since these soils are low in native nutrients, the methods of fertilization
and liming may be manipulated to retard growth of Fucarium and to reduce the inci-
dence and severity of disease. Fusariium requires most of the same nutrients to
grow in the soil as do tomato plants. There are, however, important differences
in the responses to sources and amounts of nutrients available. While the tomato
may explore a large portion of the topsoil with a fairly extensive root system,
Fusarium growing units are limited to their microenvircnment. If the soil infes-
tation level of Fusarium is low, the rate of proliferation and disease-production
may be limited by using localized fertilizer placement to feed tomatoes without
making fertilizer nutrients available throughout the topsoil. Thus, the systematic
evaluation of Fusarium vs. tomato nutrient requirements must emphasize differences
that may be found, to keep Fusarium contaminant propagules in a state of starvation.

Race 2 tomato wilt Fusarium was grown in various artificial media by varied
cultural procedures to learn which chemical elements are needed and in what amounts.
The fungus was found to be dependent on any one of various carbon sources tested
but did not require calcium or boron, in agreement with the literature published
on other Fusaria. Race 2 Fusarium requires a total of 12 nutrient chemical elements
while tomato requires 15. These elements are widespread throughout the environment,
especially in soils and water but the amounts present may be exceedingly small cr
they may be locked in minerals, organic matter, or may be present in an insoluble
form. The procedure contemplated for a systematic establishment of desirable soil
nutrient regimes, therefore, involves the sw-ftineg cf the nutrient balance to a
situation that will arrest the major part of the growth and pathogenic activities
of Fusarium. A model system would retard Fusarium by causing deficiencies, excesses
or nutritional imbalances. Attempts to induce toxicity by excesses of common
chemical elements were not successful on a practical basis because of the relative
tolerance of Fusarium.

Fusarium (race 2) was cultured in artificial liquid media containing various
amounts of the micronutrient elements. Deficiencies of copper, iron, manganese,
molybdenum or zinc individually reduced growth and sporulation. When Manapal
seedlings were inoculated with race 2 FusarJum cultured cn Pmedia sdficient in
molybdenum or zinc, there was considerably ler. disease than fron incculum grown
with optimal zinc and molybdenum. The response of Fuserium to iron, manganese
and zinc in liquid cultures was very clear-cut. Amounts increased stepwise above







-3-


Fusarium requires potassium for growth and disease production, however, the
soil chemistry of potassium and the requirement of the tomato crop are such that
it is difficult to deprive the fungus of potassium while meeting the needs of the
tomato plant. Potassium is generally quite soluble as applied in fertilizer and
:- ins soluble in the soil. Slowly soluble sources of potassium would probably
be useful to selectively feed the plants but their cost is too great at present.
Placement of fertilizer in bands near the expanding rodt system as it develops
will decrease the general distribution of this nutrient throughout the soil and
will limit the growth of the total Fusarium population in the top soil. Fusarium
requires only very small amounts of copper and molybdenum. Soil supplies are
usually adequate for maximal growth. These elements were not studied in detail
as strategic weak points for Fusarium control in terms of limiting the availability
to the fungus.

Fusarium grew on many carbon sources including sugars, starch, cellulose,
pectin, protein and amino acids. Of these, cellulose and pectin gave a slower
growth rate because the fungus cannot digest and assimilate these complex com-
pounds as readily as others. The lack of availability of readily usable carbon
compounds in the soil will generally retard the growth of the pathogen. This fact
provides a potential soil management procedure by way of periodically or generally
starving the pathogen for readily useful carbon (energy) sources. Thus, as with
other soil-borne pathogens, it would probably be beneficial prior to planting
tomatoes to have a fallow period to cause decomposition of readily useful organic
matter residues from cover crops or weeds. Decomposing plant debris furnishes a
good growing medium for Fusarium because inorganic nutrients, as well as carbon
sources, are released into the soil solution. Acid and chelating chemicals pro-
duced during the breakdown of plant material also mobilize additional nutrients
from the soil. The effects of readily decomposable organic matter and various
carbon compounds on Fusarium growth and virulence is very complex and represents
the total effects of soil ecological considerations in the competition among soil
microorganisms. It was found that the pathogen grew on sterilized soil-agar pre--
pared from various field plots at rates proportional to wilt development in the
various plots. When agar plates were made with unfertilized soil, the lack of
nutrients almost completely prevented growth of Fusarium. This method of directly
evaluating the soil nutrient response of Fusarium and competitive microorganisms
offers a useful tool in improving methods of disease control.

SUMtARY

In summary, the first approach has been made to a systematic study of the
effects of soil nutrient regimes on Fusarium growth in soil and disease production
on tomato. It was found that any method of limiting soil nutrition of the patho-
gen was beneficial in reducing growth of Fusarium and disease development. To
utilize this approach, the first consideration must be to assure normal growth
of the tomato crop. Soil pH elevation to 6.5-7.0 together with avoidance of
unnecessary soil application of iron, manganese and zLnc will retard Fusarium
and not ordinarily affect the crop. If micronutrient deficiencies are suspected,
foliar sprays should be applied. Attention should be given to avoiding build-up
of excess fertilizer in soil, especially on a broadcast basis. Banding and
otherwise localized application of fertilizer should be used to fertilize the
crop and minimize availability to Fusarium present as contaminant infestations
throughout the topsoil. An inclusion of higher percentages of nitrate-nitrogen


I






-4-


in place of ammonium-nitrogen will retard Fusarium growth and disease. Excessive
rates of use of superphosphate and magnesium should be avoided. If deficiencies
are suspected, foliar nutrient application may be used to supplement fertilizer
applications. Soil should be allowed to lie fallow preceding planting to permit
decomposition of fresh organic matter, interrupt pathogen growth, and reduce
survival of propagules. Weeds, which may serve as alternate hosts for tomato
Fusarium, should be kept at minimal population levels.




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