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thesis entitled

"The Effect of Seed Treatment on Control
of Damping-Off of Ornamentals: and a Stuthr '-'
of a New E‘Imgal Pathogen Causing; Damping-Off."

presented by

Floyd Myron Clum

has been accepted towards fulfillment
of the requirements for

Mhdegree tum

William B. Drew

 

 

 

Major professor

 

 

-2...» .5... . ..

kg--.

THE EFFECT OF SEED TREATMENT ON CONTROL OF DAMPING-OFF
OF ORNAMENTALS; AND A STUDY OF A NEW FUNGAL PATHOGEN

CAUSINQ DAMPING-OFF

BY

Floyd Myron Clum

AN ABSTRACT

Submitted to the School of Graduate Studies of Michigan
State College of Agriculture and Applied Science
in partial fulfillment of the requirements

for the degree of
DOCTOR OF PHILOSOPHY

Department of Botany and Plant Pathology
195a

Approved M< JZ/EZ _._-_. f/LM

‘—'J" nod—--— v—v-._

A study was conducted in which seeds of fourteen
ornamentals were treated with certain of ten fungicides in
various combinations in a series of field and greenhouse
trials. In one or more trials significantly better seedling
emergence occurred when seed protectants were used on seeds
of Aster, Bachelor Button, Calendula, Cosmos, Four O'Clock,
Morning Glory, Nasturtium, Phlox, Stock, Sweet Pea, and
Zinnia. Marigold was the only ornamental on which seed pro-
tectants failed to give some measure of protection against
damping-off. Only limited protection was apparent on Lark-
Spur and Dahlia seed. Post-emergence damping-off was not
controlled by the seed protectants in these eXperiments.

An organism, with a pycnidial imperfect stage, was
isolated from a diseased Phlox seedling. This organism,
by virtue of its perfect stage, was classified in the
Aspergillaceae as that family is presently constituted.

This organism was shown to be pathogenic and caused damping-

off. A new genus and species, gycnidigpggra diSpersa, were

 

prOposed and described to embrace this organism. The life
history and morphology were studied on corn meal agar and
potato dextrose agar. Conidium and ascospore germination
and hypha deve10pment were traced.. Pycnidial deve10pment
was found to be simple merietOgenous and the cleistothecium
'was observed to arise in a similar manner from a few inter-
oalary cells in a single hyphal strand. The thirty-two
spored asci, which were scattered throughout the cleisto-

thecial cavity, were produced by crozier formation.

THE EFFECT OF SEED TREATMENT ON CONTROL OF DAWPING-OFF
OF ORNAMENTALS; AND A STUDY OF A NEW FUNGAL PATHOGEN

CAUSING DAMPING-OFF

BY

Floyd Myron Clum

A THESIS

Submitted to the School of Graduate Studies of Michigan
State College of Agriculture and Applied\Science
in partial fulfillment of the requirements

for the degree of

DOCTOR OF PHILOSOPHY

Department of Botany and Plant Pathology
195k

ACKNO‘ w’LELY? EVENTS

The author wishes to acknowledge the aid of Jr. John R.
Vaughn,formerly of Michigan State College, who suggested
the problem and under whose direction the seed treatment
project was done.

It is with sincere appreciation also that acknowledge-
ment is made to Dr. Richard L. Kiesling for his encourage—
ment and valuable criticism in the preparation of the manu-
script; to Dr. William B. Drew who acted as committee chair-
man; to Dr. Constantine J. Alex0poulos for helpful suggestions
in the field of Mycology and for suggesting the generic name
of the new fungus described herein; to Dr. Charles L. Gilly
for his assistance with the diagnoses of the new genus and
Species; to Dr. Ernst A. Bessey, Professor Emeritus, for his
assistance with the Latin descriptions; and to Mr. Philip G.
Coleman for his assistance in preparation of the photographic
materials included in this manuscript.

Special acknowledgement is given to Dr. Myron P. Backus,
Professor of Botany, University of Wisconsin, who has so
kindly given of his time for examining the cultures and
slides of gygnidigphora disperse.

Grateful recognition is given to the Northrup King and
Company, Seedsmen, Minneapolis, Minn. and the Ferry Morse
Seed Company, Detroit, Michigan who donated the ornamental

seeds used in the investigation.

Finally, full credit is due my wife, Elizabeth Bell
Clum, for her help, her unfailing encouragement and
inspiration, as well as for untold hours of clerical

assistance.

TABLE

INTRODUCTION . . . . . . .
HISTORICAL BACKGROUND. . .
MATERIALS AND METHODS. . .
Field Trials. . . . . .
Greenhouse Trials . . .
Laboratory Procedure. .
RESULTS OF SEED TREATMENTS
SEED TREATMENT DISCUSSION.
AN ASPERGILLACEOUS FUNGUS

PathOgenicity . . . . .

OF CONTENTS

Description of Organism .

PycnidiQphora gen. nov. . . .

 

CAUSING

DAM

PING-OFF.

Pycnidiophora disperse 32. nov. .

 

Spore Germination and Vegetative KevelOpment.

Pycnidial DevelOpment .

Cleistothecial DevelOpment.

LHSCUSSION OF PYCNIDIOPHORA DISPERSA

 

SIM'IARY e e e e e e e e e 0
LITERATURE CITED . . . .'.
APPENDIX C C O C O C O C O

Page

12
15
19
23
26
u?
53
53
St
Sh
56
S7
60
62
71
75

77
81

l
i
la!

1(

l]

12

LIST OF TABLES

Table Page

1 Name, chemical composition, and source of the
fungicides used in seed treatment of
ornamental varieties. . . . . . . . . . . . . 13

2 Number of seeds per replication and amount of
fungicide applied to seeds in the summer
field trials Of 1951. e e e e e e e e e o e e 20

3 Number of seeds per replication and amount of
fungicide applied to seeds in the summer
field trials Of 1952. e e e. e e o e e e e e e 21

A Number of seeds per replication and amount of
fungicide applied to seeds in the winter
greenhouse trials of 1952 . . . . . . . . . . 22

5 Effect of seed treatment on emergence and
stands of seed treated with fungicides by
commercial seedsmen; Field trials of 1951 . . 27

6 Effect of seed treatment on emergence and
stands of seed treated with fungicides by
commercial seedsmen; Field trials of 1952 . . 30

7 Effect of seed treatment on emergence and
stands of seed treated with fungicides by
commercial seedsmen; Greenhouse trials of 1951 37

8 Effect of seed treatment on emergence and
stands of seed treated with fungicides by
the author; Greenhouse trials in the winter
or 1952 e e e e o e e e e e e o e o e o e o e 39

9 'Effect of seed treatment on emergence and
stands of seed treated with fungicides;
Greenhouse trials in the winter of 1952-53. . MS

10 Composite rating of the seed—treatment
fungicides based on emergence for each
ornamental variety. 0 e e e e e e e e e e e e “B

11 Summary of mycelium, cleistothecium, and ascus
and spore ball diameters on culture media . . 66

12 Summary of pycnidium, conidium, and ascospore
length and width on culture media . . . . . . 67

Plate

II
III
IV

LIST OF PLATES

Marigold seed treatment trial . . . . . . .

Calendula seed treatment trial. . . . . . .

Aster seed treatment trial. . . . . . . . .

Figures 1 - 220 e e O o e o e o e e e e e 0

Figures in the meristogenus develOpment of
pycnidia
Figur6823-3ueeoeoeeeooeeoe

Figures 35 " 1+6 0 e e e e e e e 0 e e e e e

Page
l6

17
18
68

69
70

INTRODUCTION

The fungal organisms causing seed decay and damping-
off of ornamentals are limiting factors in seedling pro—
duction. Tilford (h3) said, "Practically all flower seed-
lings which are started in plant beds or in flats are subject
to damping-off.” There are no available official estimates
of the annual losses caused by this disease in Michigan, but

1, maintains that damping-off is a very serious

Andrews
disease of ornamentals in the state. In routine visits to
growers throughout the state he observed losses as high as
ninety percent of the seedlings in a planting. According to

Haney2

, it is a common practice among ornamental growers to
plant at least ten percent more seed than would be required
if the seedlings remained healthy, with growers frequently
planting twice the required seed in order to overcome these
losses. Aside from the added cost of seed, this practice
necessitates thinning if damping-off is not as serious as
expected, and is of little value if the disease is more
destructive than anticipated.

Damping-off pathogens attack any or all parts of the seed

 

1. Personal communication from Dr. E. H. Andrews,
.Extension Pathologist, Michigan State College, East Lansing,
Michigan.

2. Personal communication from Dr. J. D. Haney, Professor,
Department of Horticulture, Michigan State College, East
Lansing, Michigan.

and seedling. Two distinct types of injury are usually
designated, pro-emergence and post-emergence damping-off.
When a young plant is killed before it reaches the surface
of the soil, it is called pro-emergence damping-off. In
this case the embryo may sometimes be killed before the
hypocotyl emerges from the seed coat. Post-emergence
damping-off occurs after the seedling has emerged above
ground. This type of injury is characterized by a water-
soaked appearance of the stem at the ground line, usually
before the leaves wilt, followed by the teppling over of the
infected seedling.. Infection of the stem usually occurs at
or below the ground level, but if the root is attacked, the
entire root may be rotted away. Sometimes such plants will
produce adventitious roots from the hypocotyl above the
infection and recover, but these plants often remain stunted.
If the cotyledons are attacked, the seedling may be stunted
and deformed. As the plant grows older susceptibility to
the disease diminishes.

Disease—free soil, washed sand, sphagnum moss, soil
fumigation, soil sterilization, and seed treatment are used
in attempts to control damping-off. Treatment of vegetable
seed has been practiced for several years, and more recently
seedsmen have been treating ornamental seed before packeting.
.However, new seed-treatment fungicides dictate the need for
there information in regard to their powers of control of

pro-emergence and post-emergence damping-off.

The purpose of this paper is to present the results
from a series of tests of various seed treatment fungicides
for the control of damping-off of some ornamentals. The
objective of these seed treatment eXperiments is the deter-
mination of the protective value of the fungicides on four-
teen ornamental species. In the course of these investi-
gations a new pathogen (glcnidiophora disperse) causing
damping-off of ornamentals was discovered, and a morphological
study and a description of this fungus is presented in a

later section of the paper.

HISTORICAL BACKGROUND

Many workers have published on various phases of
damping-off and seed treatment. However, most of the work
published is on damping-off of cereals or vegetables. A
comprehensive review of the status of seed treatment with
special reference to cereals was published in 1936 by
Leukel (28). In an experiment station bulletin by Kadow
and Anderson (25) in 1937 on seed and soil treatment an
extensive bibliography was included. The following year
Horsfall (22) summarized some of the more important liter-
ature on damping-off. Leukel (29) reviewed the cereal seed
treatment literature in 19h8, and in the same year'Walker
(AS) reviewed vegetable seed treatment. Recently Linnasalmi
(30) has given "a comprehensive, fully tabulated account of
the author's studies at the Department of Plant Pathology,
Tikkurila, Finland, on the etiology, distribution, and
economic importance of damping-off in vegetables and orna-
mentals grown under glass, supplemented by a survey of the
literature listed in an eight page bibliography."1

Although the parasites reported as causing damping-off

are limited in number, a considerable number of such parasitic

 

1. Since this article was unavailable the above quo-
tation was taken from an abstract of the paper appearing in

Rev. App. Mycology 32:hl2-h13. 1953.

organisms are known. Species of Ezthium, Rhizoctonia,

 

Fusarium, Alternaria, Botrytis, and Phytophthora are some of

 

 

 

the organisms capable of causing damping-off. Of these,

gzthium spp., Rhizoctonia solani Kuhn, and Fusarium spp. are

 

 

the more important organisms associated with seed decay and
damping-off of ornamentals (h,6,l3,15,28,30,32,35,37,38,39,h7).
According to Hartley (20) these forms are at least better
known, if not more destructive, as damping-off organisms
than as parasites on older plants.

Since Hesse (2) in 187h first described, named, and

demonstrated pathOgenicity of 21thiumjgebaryanum, this species

 

has been proven to cause damping-off of a great number of
host plants. As a rule g. debaryanum pathogenicity tests
have been performed with vegetable and other types of plants.
Very recently Srivastaya (38,39) using Hollyhocks and the
ornamental Saponaria, and Linnasalmi (30) using Stocks have
proven by inoculation and reisolation eXperiments that
‘3. debagzanum causes damping-off of ornamental seedlings.

Rhizoctonia solani is another important cause of damping-
off. Stock, China Aster, Carnation, Hollyhock, Snapdragon,
and Saponaria were proven susceptible to this pathogen (h,6,
13.30.37a39). Baker (3) studied seed transmission of g.
solani and round mycelium of this organism in the seed of
Zinnia elegans.

Seed treatment for the control of plant diseases has

been practiced for about three centuries. However, early

practices were not scientific because the nature and causes
of plant diseases were not understood. Practices such as
sowing in the dark of the moon were of a superstitious
nature. Other early practices used from time to time con—
sisted of the application of lime, salt, salt-peter, and
wood ashes to cereal seeds.

Cepper sulfate was suggested as a seed treatment by
Schulthess in 1761 (us). General usage of cOpper sulfate,
however, did not come about until a century later. Prevost
(36) in 1807 demonstrated that cepper prevented the germi-
nation of spores of the bunt fungus. Modifications in the
recommendations of its use appeared during the middle 1800's,
the most important of which, according to Leukel (28), was
the addition of lime water to prevent seed injury. The hot
water treatment develOped by Jensen (2k) in 1887 is one of
the treatments used to kill pathogens inside the seed.
Walker (hS) points out that Guether in Germany in 1895 was
the first to advocate the treatment of grain seed with
formaldehyde solution. Its use was also advocated about
this time, as a soil treatment to prevent damping-off (8).

Methods had been worked out for the control of some
seed-borne pathogens of cereals by 1900, but attention in
the first decade of the 1900's shifted to other seed-borne
diseases particularly of vegetables. Mercuric chloride and
other materials were tried up to about l9lh but were not

generally recommended. However, after 1912, organic mercury

compounds were found to be effective seed treatment materials
for cereal disease control. This marks the beginning of the
use of organic materials as seed treatment compounds.
Walker (hS) states that seed treatment for protection
against soil-borne organisms did not receive much attention
until after 1925. It soon became apparent, moreover, that
fungicides applied to the seed would not only kill or
inhibit seed-borne parasites, but would also give some
measure of protection against soil inhabiting fungi (1,10,
12,19,21). Soon seed treatment dusts came into prominence
and met with immediate pOpularity. With the successes of
the organic mercury compounds other materials were investi—
gated. Of these cuprous oxide and zinc oxide were found to
be effective in many cases as seed protectants, but tended
to cause injury. Because of the shortage of cepper and
mercury during World War II, a search for some organic
materials was stimulated. Spergon, Arasan, and Phygon are
examples of organic seed treatment compounds which are
widely used. More recently liquid mercuric compounds such
as phenyl ammonium mercuric acetate have come into use.
Tilford (A3) in 1931 reported that the most effective
control of damping-off was accomplished by the prOper hand-
ling of a correctly sterilized soil, but that growers would
not or, because of lack of equipment, could not steam steri-
lize soil. This method is satisfactory if recontamination

of the soil is prevented. Other methods of soil treatment

for control of damping-off have been tried from time to time
with varying degrees of success. Tilford (h3) secured
excellent control of the disease on 22 Species of flower
seed when be mixed six percent formaldehyde dust with soil
at a rate of 1% ounces per square foot. Two years later
Wilson and Tilford (h?) again improved the seedling stands
of several ornamental varieties by the use of formaldehyde
dust. Some varieties were reported by these authors not to
be benefited, whereas others were injured by this chemical.
Doran (15), in 1938, dealt exclusively with soil treatment
for the control of damping-off of ornamentals. In this
investigation he found that the following materials were of
value in certain cases: washed sand, calcium cyanamide,
acetic acid, pyroligenous acid, c0pper-lime dust, ammonia,
formic-acid, formaldehyde, acetaldehyde, salicylic acid, and
aluminum sulfate. Lammerts (27) using five percent ethyl
mercury iodide obtained good control of both pre- and post-
emergence damping-off when the chemical was applied to the
soil at the rate of 1% grams per square foot. Dimock (13)
reported that Rhizoctgnig damping-off of Stocks can be con-
trolled by sterilization of the soil with steam or chloro-
picrin (10 cegbu.ft.). Later Newhall and Lear (33) recommended
the use of methyl bromide (11 cc./cu.ft.) or Dowfume G

(50 cc./cu.ft.) as soil treatments for controlling damping-
off. The most recent soil treatment material, 8-quinolinol

and its benzoate and sulfate salts, has been shown by

 

 

Stoddard and Zentmyer (hO) to control both pro. and post-
emergence damping-off of several ornamental and vegetable
varieties.

The utilization of different substrates for the control
of damping-off has also been tried. Dunlap (17), in 1936,
obtained satisfactory development, combined with a reduction
in the incidence of Bhiggctonia and Pythium types of damping-
off when a number of seedlings were grown in pure brown sea
sand supplemented with a mineral nutrient solution. In 19hl
Stoutmeyer 32 31. (k1) showed that damping-off of several
ornamentals was prevented by the use of shredded sphagnum
as a medium for seed germination.

Chemicals applied as liquid drenches have been tested
for control of post-emergence damping-off. Dimock (1h),
in 1951, recommended a Semesan (1-2 1bs./100 gal. water)

drench to control ghizoctonia solani infections in Stock seed

 

beds. Stoddard and Zentmyer (hO) state that 8-quinolinol
materials were definitely useful for the control of post-
emergence damping-off when applied in aqueous solution.

In case the damping-off pathOgen is seed-borne, par-
ticularly internally, more drastic measures may be necessary.
Baker (3) found that the only successful treatment of seed
of Zinnia infected with Rhizoctonia solani was hot water at

 

51.7° C (1250 F) for 30 minutes, but that this treatment

injured seed when more than one year old.

10

Because of the convenience of application and economy,
a seed treatment fungicide capable of controlling both seed
decay and seedling dmnping-off would be the most desirable
approach to this disease problem. To study the control of
damping-off, the injuriousness to seeds, and the stimulating
effects of Red COpper Oxide, Horsfall 32 21' (23) in l93h
treated seed of 107 species and varieties of vegetable and
ornamental plants with the dust. Many varieties responded
favorably to this chemical, but there were some that showed
a tendency toward injury, especially Legumes and Crucifers.
In 1937. Taubenhaus and Burkett (h2) also effectively con-
trolled pre-emergence damping-off with Cuprocide (a cuprous
oxide seed treatment). Person and Chilton (3S) and Chilton
2£_21. (9) reported that the best stands of ornamental seed-
lings were produced by treating the seed with Cuprocide and
Yellow Cepper Oxide. These investigatbrs also found that
improved stands were obtained with Vasco h and Spergon, while
New Improved Ceresan, Ceresan, and New Improved Semesan Jr.
frequently were toxic. Pre-emergence damping-off of Lilium
regale was best controlled by seed treatment with Thiosan,
Arasan, or Semesan, according to Doran (16), while Spergon,
or Fermate similarly used gave inferior results as did
several soil treatments. Recently, Linnasalmi (30) found

that seed treatment would not control Rhizoctonia damping-

 

off and only partial protection was given from Pythium

debagzanum by excess dosages of Arasan, Tayssato, Dithane

11

2-78, and Phygon. He reported that seed treatment could not
be recommended for damping-off control in Finland and
suggested that the use of a combination of physical and
chemical disinfection methods would be more likely to

prove successful.

MATERIALS AND METHODS

A series of seed treatment trials was conducted in the
field and greenhouse from 1951 to 1953 for the control of
damping-off. ~In these trials 1h different ornamentals were
treated with various seed treatment chemicals (Table 1).

No attempt has been made in this investigation to
evaluate the influence of environmental conditions on damping-
off. Instead, by inoculation and maintenance of a high soil
moisture, conditions were maintained which were favorable to
the development of the disease. This was done in order to
submit the various fungicide treatments to severe tests and
to see whether they would still be of value under these
extreme conditions.

The field tests were conducted on the EXperimental Farms
of Michigan State College. The plot of sandy loam with a pH
of 7.2 was plowed and cultivated from a sodded condition to
a garden consistency the first year and.replowed and culti-
vated for the second year. Each year oat cultures of 5235-

octonia solani Kuhn1 and Pythium debaryanum Hesse2

were added
and mixed into the soil during cultivation. The natural pre-
cipitation was augmented with a sprinkler system to maintain

a high moisture level in the soil.

 

1. The Rhizoctonia solani culture was obtained from Dr.
William Klomparens.

2. The Pythium deba anum culture was obtained from Dr.
E. S. Beneke 3 cu ure collection.

 

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The greenhouse trials were conducted in the Science
Greenhouses of Michigan State College. The soil was pre-
pared by mixing a rich loam with sand at a 1:1 ratio to which
a small portion of well-decayed peat was added. This mixture
was approximately pH 7. Oat cultures of Rhizoctonia solani
and gythium debaryanum were added to the soil at the time of
preparation to augment the fungi naturally present. Such a
soil mixture was used for two to three successive plantings.
Afterward, about half of this soil was diluted with a new
mixture, prepared as above, and replanted.

Regulation greenhouse flats were used for the plantings;
light conditions were those normally found in a greenhouse
for the time of year; an average temperature of 650 to 67° F
was maintained; and the soil moisture was kept at a high
level by daily watering.

For these tests seeds were obtained from commercial
seedsmen with some seeds already treated with the chemicals
used by the seed industry. When the seeds were treated in
the laboratory, all chemicals except Vancide 51 were applied
as dusts. The dust and seeds were shaken together in flasks
until the seeds were well-coated. In all cases the excess
dust was removed after treatment. Just enough Vancide 51,
which is a liquid material, was usually applied to the seed
to moisten the seed surface, after which it was allowed to
dry. A non-treated control was planted with each replication

in every varietal test.

15

The plantings were randomized in both greenhouse and
field trials. Each variety was maintained as a separate
unit for randomization purposes. In the greenhouse each
replication was planted in a single flat by dividing the
flat into the required number of short rows (Plates I, II,
III). In the field the rows were approximately four feet
in length and a foot apart.

As soon as the seedlings appeared a daily count of the
emerged and diseased seedlings was made for a period of four
days. Subsequent counts were made every third day for three
weeks beyond the time of emergence. As the counts were made
the damped-off seedlings were removed. Some of these
diseased seedlings were placed in petri dishes and taken to
the laboratory for further study.

Statistical analysis of the data accumulated for each
variety in each trial was carried out by analysis of variance.1
Tor purposes of analysis, missing numbers were estimated by

Baten's (5) procedure.
Field Trials

The first trial was conducted in the field during the
summer of 1951. Seeds of nine pre-treated ornamental varie-

ties were obtained from the Northrup King and Company. The

 

1. Assistance with the statistical methods was given by
Dr. W. D. Baten, Statistician for The Experiment Station,
Michigan State College.

Marigold seed treatment trial

A

B
C
D
E

- non-treated
- Soergon
- Arasan
- Phygon
- C and C Shoo

5".

IV
.I'. ‘9"?

\

 

_PIATE II

 

Calendula seed treatment trial

A - non-treated

B - Spergon
C - Arasan
D - Phygon

 

Aster seed treatment trial

A - non-treated
B . Spergon
C - Arasan
D - Phygon

l9

materials used in these 1951 field trials are presented in
Table 2. Table 3 summarizes the materials used in the 1952
field trials. The seeds were treated by the Northrup King
and Company, with the exception of Sweet Pea which came
untreated and was treated immediately before planting. The
seeds were planted in late May and early June.

The third field trial was carried out during September
of 1952. Bachelor Button and Zinnia (Giant of California)
seeds from the same lots of seeds used in the earlier summer
trial were used for this trial. The fungicides used and the
amounts of each are given in Table 3. One hundred seeds per
treatment per replication and four replications were planted

for each ornamental.
Greenhouse Trials

Seeds from the 1951 summer test lots were used for the
December 1951 greenhouse trial. The amounts of the various
chemicals applied to the seed in ounces per 100 pounds are
given in Table 2. One hundred seeds per treatment per repli-
cation of Aster, Calendula, and Marigold were planted for
three replications. Two hundred seeds per treatment per
replication of Larkspur were planted for three replications.

Table h summarizes the materials used in the 1952 green-
house tests. Approximately the same amount of each fungicide
was used in the two successive experiments with Sweet Pea and

Stock. In the second eXperiment the lots of seed were

20

 

 

 

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INNER}? CF SFLE‘CDS Piaf? REPLICITI C1". JUL) .’;}"-.(,2Lill'l‘ OW FUNGI C; DE}
APPLIED TO SEEDS IT.’ T1173 SZIE'I‘CZEE 71-1.1) '.-‘RI-51LS OF 1933
‘ mamagn'armra. arms: \ a :3
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a a
Aster, American 8 8 ... 5.3 5.3 ... 100 h
Beauty
Bachelor Button 8 8 8 5.3 5.3 ... 150 h
Calendula, Double 8 8 8 5.3 5. 8 100 h
Orange King
Cosmos, Sensation h h 6 2.0 “.6 h 100 h
Dahlia, Unwin's h h 6 2.6 2.6 h 100 h
Dwarf Hybrid
Four O'Clock, 2 2.5 a ... 2.0 2 50 ha
Marvel of Peru
LarkSpur, 8 8 12 ... 5.3 8 150 4
Double Mixed
Marigold, African 8 8 12 ... 5.3 8 100 h
Morning Glory, h h 8 ... 2.6 ... 75 h
Heavenly Blue
b
Nasturtium, Glor. 2 2 h ... 2.0 ... 25 h

Gleam Hybrid

Zinnia, Giant of 8 8 ... 5.3 5.3 ... 100 h
California

Sweet Peac 8 ... ... h.0 ... h 100 h

—__

 

a. Only enough seed in the Arasan treatment for three
replications. _

b. Only enough seed in the Arasan treatment for two
replications of 25 seeds, one of 22 seeds; no fourth repli-
cation.

0. Sweet Pea seed also treated with N. I. Ceresan
(2.5 oz./1OO 1bs.), Orthocide hO6 (h oz./lOO lbs.), and
'Vancide 51 (6 oz./lOO 1bs.).

22

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weighed with an analytical balance before and after the
application of each fungicide in order to determine accuratel
the amount adhering to the surface of the seeds.

Seeds of Phlox (Drummondii), treated by the Northrup
King and Company with Arasan (8 Oz./100 lbs.), Spergon
(8 oz./lOO lbs.), and Orthocide 75 (5.3 oz./lOO lbs.), were
planted in the greenhouse in December 1952. Fifty seeds per
treatment pre replication with a total of eight replications
were planted.

Untreated Phlox (Drummondii) seed was treated immediately
before planting in January 1953 with Phygon, Arasan, Spergon,
N. I. Ceresan, Orthocide toe, Red COpper Oxide, and Vancide 51.
All but Vancide 51 were applied to the seed as dusts and
excess dust removed. Enough Vancide 51 was applied to the
seed in order to moisten the surface; the seed was dried
immediately. Twenty-five seeds per treatment per repli-

cation were planted. There were eight replications.
Laboratory Procedure

The damped-off seedlings, which were brought into the
laboratory were washed, surface sterilized with two parts of
commercial sodium hypochlorite (Chlorox) and one part of
70 percent alcohol, rinsed in sterile distilled water, and
placed in petri dishes containing water-agar acidified with
a drOp of lactic acid. As the fhngal organism deve10ped,

hyphal tips were transferred to potato dextrose agar slants.

24

It was during the examination of these slants that a
culture, number 1036, obtained from a damped-off Phlox
seedling, was observed to be producing pycnidial imperfect
and cleistothecial perfect reproductive structures. This
combination of factors seemed to warrant further investi-
gation of the organism.

From a corn meal agar subculture single Spore isolations
were made. Advantage of the dilution technique was made in
order to isolate 17 single ascOSpores and 33 single conidia.

Difco potato dextrose agar was used for maintenance of
all cultures and as a medium to ascertain fungal character-
istics. Difco corn meal agar was used to ascertain the gross
and developmental characteristics of this organism. On the
later medium the mycelial growth was limited, which permitted
easier observation of pycnidial and cleistothecial development.

In observing spore germination and mycelial, pycnidial,
and cleistothecial deve10pment modified Van Tieghem cells
were used. These were made by sealing sterile glass rings
18 mm in diameter to sterile microscOpe slides with petroleum
jelly and placing the slides in sterile petri dishes.

Several drOps of sterile distilled water were placed in the
rings. Sterile 22 mm square cover glasses, coated with a
thin layer of corn meal agar and inoculated with a small
amount of spore suSpension, were placed medium side down on
the glass rings. These cultures were allowed to develop

for 12 to 2h hours and then observed.

Measurements of conidia, ascospores, mycelia, and asci
were made under oil immersion with a screw micrometer ocular
(97 x 10X). Cleistothecia and pycnidia were measured under
high dry with an ocular micrometer (10 x 43X). All dimen-
sions given in the paper are based on fifty measurements per
structure on each culture medium.

To establish the pathogenicity of culture 1036, erlen-
meyer flasks (250 or 500 ml), which contained a sterilized
mixture of sandy soil, were inoculated with the fungus. It
was allowed to become established for two or three days and
then seeds of Phlox, Aster, and Regal Lily, which had been
surface sterilized by placing in a sodium hypochlorite
solution in alcohol, were planted. These flasks were placed
by a west window. Flasks not inoculated with the fungus
were used as checks. 8

The diseased seedlings were treated as those coming
from the field, surface sterilized, and the diseased portions
planted on agar plates. The fungal organisms, which grew
from the diseased material, were transferred to potato
dextrose agar slants and later identified. Diseased tissue
was mounted on slides in water or lacto-phenol, crushed to
some extent, and observed.

Material for sectioning was fixed in F. A. A. and
imbedded in paraffin. The paraffin sections were stained
with Conant's Quadruple Stain.

... ,_—-——'

RESULTS OF SEED TREATMENTS

The results which were obtained in the various seed
treatment tests conducted over a period of 2% years are
presented in the following pages. These results are pre-
sented in tables so arranged as to give a comparison of
the efficiency of the seed treatment chemicals on each
ornamental variety in a particular trial or series of trials.

In Table 5 are included the results obtained in tests
in which Phygon, Arasan, Spergon, and C and C Shoo were
compared in the 1951 field trials. Seeds of Aster (Crego),
(Jalendula (Double Orange King), Cosmos (Sensation), Dahlia
(Unwin‘s Dwarf Hybrid), Four O'Clock (Marvel of Peru),
Iiarkspur (Giant Imperial), Marigold (Harmony Dwarf), Morning
C}lory (Heavenly Blue), and Nasturtium (Dwarf Choice) were
Llsed. The seeds were received pre-treated by a commercial
aseedsman who did not treat each seed variety with every
chemical.

The average temperature during this experiment was
690 I“ which was about 1.50 below normal for this period.l
TkUB precipitation was also below normal for the period, but
this was supplemented by artificial means. Heavy rains did

occur shortly after the plantings were made.
1. Local Climatological Data, U.S. Dept. of Commerce,
weather Bureau, East Lansing, Michigan.

 

 

 

 

 

 

27

 

 

 

 

 

 

 

TABLE 5
'.?26 ‘T O? SEED ThBiTHZNT OH 'MERHZ‘JZ AND STANDS OF SEED
TR? WATSJ WITH FUNGICIDES BY SOMWBRJIAL SEBJSMEN
Field trials of 195
8 Via- Non- “T C & C
bility treated Phygon Arasan Spergon ShOO
,o
Aster, Crego, Mixed
% Emergence 61 25.08 28.50 26.42 2h.25 ...
% E. 3. 13-08 1. 33 0.88 1.58 1.72 ...
% Stand 2u.75 28.25 26.00 23.83 ...
Calendula, Double Orange King
% Emergence 87 u8.u1 6t. 33”” 57.17* 49.17 ...
% E. s. D-O 1.021.36,% 0.58“ 1.03 ...
% Stand “.8000 63. 76" A 56.83" (4,8050 .00
Cosmos, Sensation
% Emergence 93 52-38 68-50% 66 88% 53‘12 "'
% E. S. D-O 0.95 1.26 0 75 0.71 ...
% Stand 51.87 68.62* 66. 38* 52.75 ...
Dahlia, Unwin's Dwarf Hybrid, Mixed
% Emergence 81 “2075 0.. 57050 44.12 000
% E. so D-O 0088 000 1030 0086 00.
% Stand “.2038 one 5607; (+3075 000
Four O'Clock, Marvel of Peru
7 Emergence 81 70.50' ... 74.00 70.00 ...
% E. s. D-O 0.71 ... 0 0 ...
% Stand 70.00 ... 7u.00 70.00 ...

 

a. Emerged seedlings damped-off.

* Significant at 5% level
"* Significant at 17 level

TABLE 5 Continued

 

 

 

 

 

 

Via- Non- C & C
bility treated Phygon Arasan Spergon 5800
/O
LarKSpur, Giant Imperial
% Emergence 80 38.58 h7.00 h5.67 37,92 81-92
5 E. s. D-oa 6.08 5.67 5.66 7.25 7.36
7 Stand 36.08 88.33 M3.08 35.17 38.83
Marigold, Harmony Dwarf (French)
p Emergence 7h 61.08 60.67 58.58 59.08 55.83
5 E. S. 0-0 0.18 0.1a 0.18 0.12 0
% Stand 61.00 60.58 58.50 58. 3 55.83
Morning Glory, Heavenly Blue
% Emergence 61 51.50 87.50 52.75 85.00 ...
% E. S. D-O 0.97 0.53 0 0 ...
% Stands 51.00 #7025 52075 “5000 900
Nasturtium, Dwarf Choice, Mixed
7 Emergence 82 78.00 ... 76.67 86.00 ...
%E0 80 D'O 0 co. 0 O 000
% Stand 78.00 ... 76.67 86.00 ...

 

a. Emerged seedling damped-off.
* Significant at 5% level
*% Significant at 1% level

29

The incidence of post-emergence damping-off in this
planting was slight. Less than two percent of the emerged
seedlings damped—off except Lark3pur seedlings where not
more than eight percent damped-off. Pro-emergence damping-
off on the other hand was apparently more severe. Less than
one-half the viable seed (according to viability percentage)
emerged in the case of Aster. Emergence of Calendula, Cosmos,
Dahlia, Larkspur, and Marigold was considerably below the
viability level of the seed. Nasturtium seed, however, was
not very susceptible to pre-emergence damping-off.

Significant improvement of the seedling emergence and
stands was obtained only in the cases of the Phygon and
Arasan treatments of Calendula and Cosmos seed. Although
not significant, the increases due to Arasan and Spergon
treatments of Dahlia and Nasturtium seed respectively were
substantial. In all other cases the emergence and stand
differences between the treated and non-treated seed were
slight. Such differences are in the range of experimental
variation and are not significant. Nevertheless, some of
these small differences are indicative of trends in the
value of the various chemicals as shown in subsequent
experiments.

In Table 6 are included the results obtained in tests
in which Phygon, Arasan, Arasan SF, Spergon, Orthocide 75,

and C and C 5800 were compared on seed of Aster (American

3O

 

 

 

 

 

 

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33

Beauty), Bachelor Button, Calendula (Double Orange King),
Cosmos (Sensation), Dahlia (Unwin's Dwarf Hybrid), Four
O'Clock (Marvel of Peru), Larkspur (Double Mixed), Marigold
(African), Morning Glory (Heavenly Blue), Nasturtium (Glor.
Gleam Hybrid), Zinnia (Giant of California), and Sweet Pea.
With the exception of Sweet Pea the seeds were pre—treated.
As in the 1951 trials not every variety was treated with
each chemical. All varieties were used in the May-June
trials. In the fall planting only Bachelor Button and Zinnia
were used. The seeds used in the second planting were from
the same lots as were used in the summer plantings. In the
summer trials Calendula, Cosmos, Dahlia, Four O'Clock,
Marigold, Morning Glory, Nasturtium, and Zinnia were planted
during the third week of May and Aster, Larkspur, and Sweet
Pea during the first week of June.

The temperature was a little above normal during the
summer eXperiment with an average during the entire period
of 68° F. The last part of May was cool, however, with an
average of 580 F. The average temperature of June and the
first half of July was 72° F; this was about three degrees
above normal. The cool May weather occurred in connection
with heavy precipitation in that period, while it was dry
<1uring June and July. Of course, as pointed out earlier, a
liigh soil moisture level of the plot was maintained by a

Sprinkler system. The average temperature during the fall

eXperiment was 640 F. The soil moisture was high during
the first week because of considerable precipitation right
after the planting of the seed.

Damping-off was much more severe than in the previous
year. In one case, post-emergence damping-off caused a loss
of 63 percent of the emerged seedlings. In many instances r
these post-emergence losses were more than 10 percent.
Emergence in relation to seed viability was lower in 1952,

indicating that the incidence of pre-emergence damping-off

 

was also greater. Although susceptibility to damping-off
was not studied, some differences in post-emergence sus-
ceptibility were apparent.

Seedling emergence of Phygon-treated seeds was signifi-
cantly improved over the non-treated seeds of Bachelor
Button (both plantings), Calendula, Cosmos, Four O'Clock,
Morning Glory, Nasturtium, Sweet Pea, and the fall planting
of Zinnia. Although not significant, noteworthy emergence
improvement due to the Phygon treatment of Aster, Dahlia,
and Zinnia (summer planting) seed was produced. Seedling
emergence of LarkSpur and Marigold was only slightly improved
by the Phygon treatment.

Seedling emergence of Bachelor Button (both plantings),
Four O'Clock, Morning Glory, and Zinnia (fall planting)
seed treated with Arasan was significantly better than the
lion-treated. Substantial improvement was also noted in the

<3ase of LarkSpur and Zinnia (summer planting). In every

 

 

 

... up! .... ' rrl.

a

other case only slight improvement of the average emergence
occurred.

The performance of Arasan SF was generally similar to
Arasan, wherever they were both used. The notable exception
was to be found with Cosmos, where the emergence of Arasan
SF-treated seed was significantly better than the Arasan.
Although significant differences did not exist, the Arasan SF
treatment was the best chemical used on Dahlia seed.

Spergon as a seed treatment chemical generally was of

irr'I-fJ—mm.“ W73“

little value except for Four O'clock and Morning Glory.
Substantial improvement of the emergence and final stand
of Bachelor Button seedlings were produced in the summer
planting, but not in the fall trial. Since Spergon was
found to be of little value on Aster and Sweet Pea in
earlier trials it was not used on these species in this
trial.

Orthocide 7S-treated seed emerged significantly better
in the case of Bachelor Button (both plantings), Cosmos,
Four O'Clock, Morning Glory, Nasturtium, and Zinnia (fall
planting). It was also an outstanding chemical on Aster
and Zinnia (summer planting). In other instances, that is,
Calendula, LarkSpur, and Marigold, emergence of Orthocide 75-
treated seed was little better than the non-treated.

C and C Shoo as a seed treatment chemical proved to be
of significant value only on Calendula and Cosmos seed. It

did substantially improve emergence of Four O'Clock seed,

36

but this was still inferior to other treatments.

Aside from Phygon only N. I. Ceresan proved to be of
any value for treating Sweet Pea seed to increase emergence
in this summer trial.

The frequency of the different fungi causing post-
emergence damping-off was determined for the damped-off
Zinnia seedlings of the fall planting. When the organisms
' were allowed to grow out of diseased tissue on agar plates
the following percentages of the different fungi deveIOped:

Rhizoctonia solani 65, Fusarium Spp. 11, and various other

 

fungi 2h. Some of the various fungi were: Penicillium,

 

Alternarig, Rhiggpug, Hormodendron, HelminthOSporium, Tri-
choderma, ghgma.

The results of the tests in which Phygon, Arasan,
Spergon, and C and C Shoo were tested on seeds of Aster
(Crego), Calendula (Double Orange King), Larkspur (Giant
Imperial), and Marigold (Harmony Dwarf) in the greenhouse
tests of 1951 are given in Table 7. These seeds were from
the same lots of seeds of these Species used in the summer
1951 trials. The percentage of seedling emergence for all
four varieties was in the general range of that obtained in
the summer trials.

The Phygon and Arasan treatments were significantly
effective in improving both emergence and stands of seeds of
Aster and Calendula. Spergon although significantly better

than the non-treatment was still significantly poorer than

4—.
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1 “in “ii-(mi; .. ' .-.
O

 

 

 

 

 

 

 

TABLE 7
EFFECT OF SEED TREATWBJT ON LMEKGBN 3E AND STANDS OF SEED
TREATY-1 mTTEi TUL‘IIJIDZ BY COILLEIiCIAL SEEDSMEN
Greenhouse trials of 1951
Via- Non- C & C
biiity treated Phygon Arasan Spergon ShOO
Aster, Crego, Mixed
% Emergence 61 9.33 29.00“" 26. 33%;" 15.67” ...
% E. S. 0-081 3.57 5.33., 2. 53 12.77 ...
% Stand 0.00 23.67** 25. 67“ 13.67 ...
Calendula, Double Orange King
% Emergence 87 32.33 77.33** 73.00** u3. 33* ...
% E. s. tho 6.18 1.72”) 1.37”” 0. 77 ...
% Stand 30.33 76.00"* 72.00" u3 00* ..-
LarkSpur, Giant Imperial
% Emergence 80 [+7.00 50.67 [+6050 “.2016 14-1033
% E. s. 0—0 1.06 0.97 1.08 3.16 1.61
% Stand u6.50 50.17 46.00 to. 33 no.67
Marigold, Harmony Dwarf (French)
% Emergence 7h 56.67 60.33 61.33 56.33 Sh. 33
%.E. s. DbO 1.76 2.76 O 2.37 1.23
% Stand 55.67 58.67 61.33 55.00 53 67
a. Emerged seedling sdamped-off
* Significant at 57 level
35%: Significant at 1% level

 

 

J}. {‘1
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‘wflflVH "I; .~‘

38

Arasan and Phygon with Aster and Calendula. LarKSpur and
Marigold did not respond to any degree to the treatments in
this trial, and some treatments were even slightly inferior
to the non-treated check.

In Table 8 are presented the data from a series of
eXperiments conducted in the greenhouse during the early 9
months of 1952. In this series of trials untreated seed
was obtained and treated by the author with Phygon, Arasan,

Spergon, C and C ShOO, N. I. Ceresan, Red COpper Oxide, and 3

 

Vancide 51. Orthocide hO6 was also used in three cases.
The ornamentals used were: Calendula (Double Orange King),
Stock, in two eXperiments, Sweet Pea, in two eXperiments,
and Aster (Crego).

The seedling emergence of Calendula was substantially
improved by all seed treatment chemicals. Spergon was the
least effective. Some of the treatments nearly doubled the
seedling emergence and final stands. Vancide 51, Phygon,

C and C Shoo, Arasan, Red COppeP Oxide, and N. I. Ceresan,

in that order, were all highly significant treatments. About
a 2h-hour delay in germination was caused by the Ceresan.
This delay, however, was only temgorary, so that by the end
of the eXperiment the seedlings were as large and vigorous

as any others.

Seed treatment of Stock seed benefited the emergence
and stands as shown by the two successive trials. The same

seed was used in both trials. The N. I. Ceresan treatment

39

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was aoout the best in each instance. In the first trial
N. I. Ceresan, Vancide Sl, Phygon, Red Cepper Cxile, and
Arasan treated seed in that order, produced emergence and
stands significantly better than the non-treated control and
the Spergon and C and C ShOO treated seed. The Spergon
treatment was considerably poorer than no treatment. In
the second trial where approximately the same amount of each
fungicide was used as in the earlier trial the results were
somewhat more variable. All chemicals used improved emergence
and final stands; however, emergence of Phygon- and Spergon-
treated seed was not significantly better than that of the
non-treated. The treatments giving significant improvement
in seedling emergence were: C and C 5400, N. I. Ceresan, Red
COpper Oxide, Orthocide hob, and Vancide 51 in that order.
The relative occurrence of the different fungi causing
post-emergence damping-off was determined for the second
trial of Stock. When the organisms were allowed to grow
out of the diseased tissue on agar plates the following

percentages of different fungi deve10ped: Rhizoctonia

 

solani 3h, Ezthium epp. 1h, Fusarium spp. u, various other
molds 11, and none 37.

Sweet Pea seed, like Stock, was used in two successive
trials, in which approximately the same amount of each
chemical was used in each trial. Not only were the results
from chemically treated seed significantly better than the

non-treated, but certain chemicals were significantly better

14.2

than others. Although some variation in the results was

evident between the eXp-eriments, in the main the results were

complementary. Since post-emergence damping-off was not

controlled by the chemicals used, conclusions are based on
the emergence data and protection against pre-emergence

damping-off. Based on the results obtained in these two

trials the chemical treatments fall into four groups: 2

l. Phygon and N. I. Ceresan; 2. Vancide, C and C ShOO, and

“5". .' 21'1". u.“ (”I

Orthocide h06; 3. Red Cepper Oxide and Arasan; and u. Spergon,

 

from the best to the poorest in that order. The Spergon
treatment was little better than the non-treated. The Arasan
treatment gave significantly better emergence only in the
second trial, while Red COpper Oxide proved to be better in
both trials. The C and C SliOO, Vancide 51, and Orthocide
[#06 treatments gave about equal pre-emergenoe protection.
PhYgon and N. I. Ceresan were superior to all other treat-
ment-,3 and gave protection significantly better than some
Other treatments. For example, these treatments were
Significantly better than all others in the first trial.
This superiority was still found in the second trial, but
the differences were not quite so great.

No chemical injury of the Sweet Pea was apparent,
eFifi-"apt that some Red Cepper Oxide treated seeds were slow
to germinate. When these seeds were dug up many could be
f°‘-lh.<:i that had not swollen and were still well-coated with

the chemical. Once the seed became swollen by the uptake of

1&3

water, it would germinate readily. This would indicate

that; the Red Cepper Oxide coating on these seeds coupled

with the hard seet coat prevented the entrance of moisture

into the seed and thus delayed or even in some cases pre-

vent ed germination .

The relative occurrence of the different fungi that grew

out of a few of the damped-off Sweet Pea seedlings was

determined in the first experiment. The following percent-

ages 7 of the different fungi that develOped are: Pythium Spp.
70, Rhizoctonia solani 7, Fusarium spp. 8, and other various
fungi 114,. In the second trial with Sweet Pea all the

diseased seedlings were checked. The following fungi were

found: {Rhizoctonia solani 60, Pythium spp. 11+. Fusarium app.

3: other various fungi 15, and none 8. Thus, on the same

8011, the relative prevalence of the damping-off fungi
differed from that in the previous eXperiment.

In the experiment in which Aster was used all chemical
“‘3 atments proved to give better results than did the non-
tn‘eadsment. Emergence of Spergon and Red COpper Oxide treated
596d were not significantly better than the non-treated,
hOWever, Arasan, Orthocide 1.06, Vancide 51, N. I. Ceresan,
C 8LI'ld C 51400, and Phygon, all about equally effective, were
531Strificantly better. Although final stand differences were
not; significant, the final seedling stands were superior

“here the chemical treatments of the seed were US94-

In Table 9 are presented the results of two successive
greenhouse experiments using Phlox (Drummondii) seed. Two
earlier eXperiments using Phlox in the field had been washed
out so badly that it was impossible to read the results. In
the first experiment in December of 1952 the seed was pre-
treated with Arasan, Spergon, and Orthocide 75. For the
second eXperiment in January 1953 untreated seed was treated
by the author with Phygon, Arasan, Spergon, N. I. Ceresan,
Red COpper Oxide, Orthocide toe, and Vancide 51.

Arasan and Orthocide 75 increased the number of emerging
seedlings significantly over the non-treatment and the
Spergon treatment in the first trial. In the second experi-
ment differences were not statistically significant although
some of them appeared substantial. Orthocide h06, N. I.
Ceresan, Arasan, and Red COpper Oxide were the better seed
treatment chemicals. Phygon, Spergon, and Vancide 51 were
of no real value. It is noteworthy that the performances
of Arasan and Orthocide (Orthocide 75 and Orthocide too
have the same active ingredient but contain 75 and 50 per-
cent reSpectively) treatments were about equally effective
in the two eXperiments.

The fungi causing seedling damping-off were determined
for some of the diseased Phlox seedlings in the December
trial. It was found that 86 percent of these seedlings
yielded Rhizoctonia solani and 1h percent various other

fungi. One of the various other fungi when studied further

MS

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was found to be a new damping-off causing organism.

study is reported in another section of this paper.

This

[4.6

SEED TREATMENT DISCUSSION

Chemical seed treatment as a means of checking pre-
emergence damping—off of ornamentals has proved to be bene-
ficial for many of the Species tested in these trials. The
protection varied not only from checmial to chemical but
also from Species to Species. The relative values of the
fungicides tested on the different ornamentals included in
these eXperiments are shown in Table 10. The fungicides are
rated as superior, promising, doubtful, and of no value,
according to the emergence data only.

In those Species where two varieties were used as in
the trials with Aster (Appendix Figs. l-h), Larkspur (Appen-
dix Figs. 17-19), and Marigold (Appendix Figs. 20-22) the
relative value of each fungicide did not vary from variety
to variety. However, under the conditions of these eXperi-
ments these differences were generally similar to the
differences between the various lots of seed of the same
variety as in trials with Calendula (Appendix Figs. 5-8) and
Sweet Pea (Appendix Figs. 29-31). Each variety has been
treated separately in Table 10.

From this table it can be seen that some chemicals
were generally more effective as ornamental seed protectants
than others. The most consistently valuable fungicide was

Phygon, while Spergon was the poorest. Even when the dosage

COMPO SI TE RATING OF

THE

TABLE 10

SEED-TREATMENT

ON EMERGENCE FOR EACH ORNAMENTAL VARIETY

FUNGICIDES BASED

 

 

Ornamental Superior Promising Doubtful No value
variety
Aster, Crego Phygon Red Can
Arasan Spergon
N.I.Ceresan
Vancide 51
c a c 5400
Ortho. toe
Aster, Phygon Spergon
American Beauty Ortho. 7S Arasan SF
Arasan
Bachelor Button Phygon Arasan Spergon
Ortho. h06 Arasan SF
Calendula, Double Phygon Arasan Spergon
Orange King Vancide 51 Ortho. 75
C & C Shoo Arasan SF
Red Can
N.I.Ceresan
Cosmos, Sensation Phygon Spergon
Arasan SF
0 a c 5400
Ortho. 75
Arasan
Dahlia, Unwin's Arasan Spergon
Dwarf Hybrid Arasan SF C a c Shoo
Phygon Ortho. 75
Four O'Clock, Arasan C a C 5400
Marvel of Peru Ortho. 75
Phygon
Spergon
Larkspur, Phygon Arasan Spergon
Giant Imperial C & C 5400

 

a. Red COpper Oxide

M9

 

 

 

——_.J_

a. Red COpper Oxide

TABLE 10 Continued
Ornamental Superior Promisin' Doubtful No value
variety ~ ‘ ‘5 ” ‘
LarkSpur, Double Arasan Phygon
Mixed Spergon
c a c Shoo
Ortho. 7S
Marigold, Phygon Spergon
Harmony Dwarf Arasan C a C 5400
Marigold, African C & C SQOO
' Phygon
Arasan
Ortho. 7S
Spergon
Morning Glory, Phygon
Heavenly Blue Arasan
Spergon
Ortho. 7S
Nasturtium, Dwarf Spergon Arasan
Nasturtium, Glor. Phygon Spergon
Gleam Hybrid Ortho. 75 Arasan -
Phlox, Drummondii Ortho. 75 Phygon Vancide 51
Ortho. uoe Spergon
Arasan
N.I.Ceresan
Red Can
Stock N.I.Ceresan Spergon
Arasan '
Vancide 51
Red Cuoa
Phygon
c a c Shoo
Ortho o (4.06
Sweet Pea Phygon Vancide Red Can Spergon
N.I.Ceresan Ortho. toe Arasan
C & C 5400 Arasan SF
Zinnia, Giant of Ortho. 7S Arasan
California Arasan SF Phygon

of Spergon was increased it was still a poor treatment. On
only two ornamentals, namely Morning Glory and Nasturtium,
did the Spergon treatment respond at all favorably. Arasan
was generally promising, but did not always measure Up to
Phygon. In some instances, however, it was somewhat better.
Arasan SF was of no more value than Arasan. N. I. Ceresan
was a very promising seed protectant, however, its potential-
ities were not fully investigated in these experiments. It
is reported to be injurious on some plants. The Orthocides,
even though of different concentrations, were generally
effective in pro-emergence control. Red Cepper Oxide, used
to only a limited degree, was of some value, but generally
was outranked by some of the organics. Vancide 51 was of
value where used.

Marigold was the only ornamental on which the seed pro-
tectants failed to give some measure of protection against
pre-emergence damping-off. Only limited protection was
apparent on Larkspur and Dahlia. Perhaps higher dosages of
the fungicides would have given more protection. In contrast
the most noticeable protection was provided Sweet Pea against
pre-emergence damping-off when seed protectants were used.

The eXperimental data shown in graphic form (Appendix
Figs. 1-35) do not in any case indicate that any one chemical
contributes much toward post-emergence damping-off control.
This is best illustrated by the two successive Sweet Pea

trials (Appendix Figs. 29-30). The emergence data in the two

 

eXperiments are very well correlated even though damping-
off was more severe in the second trial. The stand data,
on the other hand, were conflicting.

Tisdale gt El' (uh) reporting on dust treatments for
vegetable seed, also concluded that, "Seed treatments provide
little protection against post-emergence damping-off, even
though they are very satisfactory in preventing seed decay."

The post-emergence damping-off susceptibility of the
ornamentals studied in these eXperiments may be rated by
Species as: very susceptible - Aster and Sweet Pea; moder-
ately susceptible - Calendula, Dahlia, Larkspur, Phlox,
Stock, and Zinnia; slightly susceptible - Bachelor Button,
Cosmos, Four O'Clock, Morning Glory, and Nasturtium; and
semi-resistant - Marigold.

Damping-off generally became more severe with each
successive use of the same soil in both greenhouse and the
field (Appendix Figs. 1-35). Environment in the field could
have been partly reSponsible for this, but it would seem more
logical to consider this a function of inoculum potential.
Inoculum potential was enhanced in both the field and the
greenhouse by soil inoculations, but in the greenhouse where
the soil was used a second and even a third time the damping-
off was invariably higher on successive trials. This was
well illustrated by the Sweet Pea trials (Appendix Figs. 29-
30). Since the inoculum potential tends to increase in

successive plantings on the same soil, the use of fresh soil

 

 

l ...-

\Jl
[‘0

in the greenhouse and rotation in the field would tend to
lessen damping-off. This would be control through escape.
A partial check of the parasites responsible for post-
emergence damping-off was made and it was found that the
organisms reSponsible changed from one trial to the next.
Although exact data were not taken in the 1951 field trials q
the organisms primarily responsible for post-emergence
damping-off were pythiaceous. In the 1952 fall eXperiment

it was primarily Rhizoctonia which was causing the seedling

 

damping-off. Temperature differences for the different 2
trials hardly would account for this since the Pyghigm spp-

are favored by cooler temperatures and it was the Rhizoctonia

that caused the damage in the fall trial. This change was

also evident in the greenhouse with the Sweet Pea trials

where the temperature and moisture conditions were more

uniform.

Several lines of further research are suggested by these
experiments. Further investigation of the dosages required
for each of the better chemicals for each species is suggested.
EXpand the investigation to include more ornamental Species,
always keeping in mind that the commercial seedsmen will
use such information for pre-treating practices. Study post-
emergence control procedures. Through controlled inoculation
and reisolation experiments of the various damping-off fungi
establish the host range of these pathOgens on ornamentals.
‘Inyestigate damping-off and control methods in relation to

environmental factors.

N ASPERGILLACEOUS FUNGUS CAUSING DAMPING-OFF

In the laboratory, while studying a group of cultures
isolated from damped-off Phlox seedlings, an unidentifiable

fungus, number 1036, was found.
Pathogenicity

Proof of the ability of this organism to cause post-
emergence damping-off was established on Aster, Phlox, and
Regal Lily. Seedlings of these varieties, when grown in
sterile erlenmeyer chambers inoculated with the fungus,
often became diseased. Symptoms of the disease were typical
of damping-off with a water-soaked appearance of the stem at
or just below the soil line. If the seedling was allowed to
remain in.the chamber then this water-soaked appearance
gradually progressed upward in the stem. Infection in the
cotyledonary leaves showed the water-soaking and chlorosis.
In.every case where these diseased seedlings were plated out
on water agar, an organism, similar in every aspect to the
'parent culture, was reisolated. MicrOSCOpic examination of
the diseased host tissue revealed the hyphal strands per-
meating through the tissues and even some evidence of cell

wall penetration (P1. IV, Fig. 22).

 

 

iii .7 fowl-l

Description of the Organism

Gross laboratory and microsc0pic observations of the
culture, number 1036, revealed features which placed it in
no known genus. By making single spore isolations of 17
ascospores and 33 conidia pure strains, identical to the

original isolate, were obtained for further study.

.-._ ... .‘W—.‘_;_‘. "n . I.

Because of the astomous and firm-walled fructification,

with globose asci scattered irregularly throughout the

cavity, the organism has been tentatively placed in the

 

Aspergillaceae. It differs from all other members of this
family by the possession of an imperfect stage, a pycnidium.
It is from this characteristic of the organism that the
generic name was chosen: PycnidiOphora, derived from the
Greek: Pyknon - idion, and phoreus; and literally meaning

”bearer of pycnidia".

PycnidiOphora gen. nov.

Cleistothecia immersa vel semiimmersa, per substratum
diapersa, globosa, immature translucentia, matura fusca et
Opaca, exostiolata, pariete membranaceo, fragili et eXappen-
diculato; hyphae immersae vel aeriae ad substratum appressae;
ascis globosis, tenuibus, delicatis, evanescentes, brevi-
‘pedicellatis, aparaphysatis, continentibus_trigintaduo Spores;
sporis conglobatis, simplicibus, oblongo-reniformis et

pallide brunneis; status imperfectus pycnidialis.

Cleistothecia submerged to partially superficial and
scattered throughout substrate, globose, translucent when
young, dark and Opaque when mature, astomous; cleistothecial
wall membranous, brittle and without appendages. Hyphae
either submerged or, when aerial, usually closely appressed
to substrate surface, the exact nature dependent upon sub- R
strate. Asci globose, thin-walled, delicate, evanescent,
short-stalked when immature, without paraphyses and with
32 Spores. Spores conglobate, unicellular, oblong-reniform

and light brown in color. Reproductive bodies of imperfect

 

stage pycnidial.

Type Species, Pycnidiophora disperse

gycnidigphora differs from the genus Fraggsphaerig
Shear by having brown asc03pores and a brown, instead of a
purple, cleistothecial wall. Although it resembles the
genera Magnusia Sacc., Arachnomyces Masses and Salm., and

Cephalotheca Fuck., the cleistothecia of this organism do

 

not have appendages. The brown cleistothecium distinguishes

this entity from the genus Laaseomyces Ruhl. Conglobate and

 

oblong-reniform spores separate it from the genus Thielavia

 

ZOpf. which produces elliptic spores.
Because of the scattered or dispersed nature of the

cleistothecia the name dispersa, from the Latin: dispergere

 

to scatter, was chosen.

PycnidiQQhora dispersa‘sp. 22:.
Mycelia homothallica, multiramcsa; hyphis l-é u in
diametro; cleistothecia 60-700 u in diametro; ascis globosis,
lO-lh.§ u in diametro; Sporis 2.0-2.9 x 2.8-5.8 u, immaturis
hyalinis et maturis pallide brunneis; pycnidia superficialia,
super substratum uiSpcrsa, globosa ad irregulariter-elongata, i
glabra, in parte inferiore incolorata, nisi cellulae circa
leviter papillatum ostiolum pallide brunneae; 26-78 x 26-164 u
in diametro; conidiOphoris Simplicibus, brevissimis; conidia

hyalina, Simplicia, oblonga, l.S-3.h x 2.6-u.75 u.

 

Mycelia homothallic, profusely branched, the hyphae
l-6 u in diameter; cleistothecia 60-700 u in diameter; asci
globose lO-lh.5 u in diameter. ASCOSpores 2-2.9 x 2.8-

5.8 u, hyaline when young, later becoming light brown.
Pycnidia scattered on surface of substrate, varying from
globose to irregular-elongate in shape, glabrous; the lower
portion colorless and the walls of the cells around the
slightly papillate ostiole light brown, 26-78 x 26-16u u in
size. ConidiOphores simple, extremely short. Conidia
hyaline, unicellular, oblong, l.S-3.h x 2.6-h.75 u.

Type specimen: Floyd M. Clum 27 from cultures prepared
during study of the organism, deposited in the Heal-Darling-
ton Herbarium of Michigan State College (accession number
133,118); isotype Specimens also deposited in the University
of Michigan and University of Wisconsin herbaria, and cultures

to be sent to the type culture collections in American Type

 

Culture Collection, Washington, 2.0. and Uentraaluureau

Voor Schimmelcultures, Baarn, Netherlands.
Spore Germination and Vegetative Development

The first visible Signs of aSCOSpore germination
(Pl. IV, Fig. 1) required 10 to 12 hours to appear. The
Spore wall apparently broke Open on the flat or concave
side and a bulbous swelling develooed (Pl. IV, Figs. 2 and
3). This swelling enlarged to approximately three times the
size of the original Spore. Then a protrusion arose on one
side of the swelling (Pl. IV, Fig. h). This protrusion
elongated into a germ tune. Generally another tube was pro-
duced from the Opposite side of the bulbous structure at
a later time, although this second tube could develOp at
any time (Pl. IV, Figs. 4 and 5a). The germ tube was ob-
served to branch at any time but usually not until it had
reached considerable length (Pl. IV, Figs. 5, 6, and 7).
Once the hyphae began to deveIOp, branching occurred quite
frequently and gave rise to a loose spreading colony with
few aerial hyphae.

Large hyphae could be traced from the center of the
colony to the edge. These larger hyphal strands were domi-
nant both on the surface and submerged and they shall be
designated throughout this discussion as primary hyphae.
Branches from these hyphae generally arose at right angles

to the parent strand and usually were smaller in diameter;

{.3

the

1.

the subsequent branches were progressively smaller, and
ultimate branch was often ass than a nTcron in diameter.
These smaller branches shall be designated as secondary hyphae.

Frequent anastomosing was observed. This occurred
between two primary hyphae lying side by side, or by the
fusion of the tips of secondary hyphae, or by the fusion of
the end of a secondary hypha and a primary hypha.

The diameter of the hyphae measured from 0.8-6.0 u on
potato dextrose agar and from 1.0-5.5 u on corn meal agar
(Table 11). Primary hyphal averages were h.? u on potato
dextrose agar and h.0 u on corn meal agar. On potato
dextrose agar the secondary hyphae averaged 2.1 u in
diameter and on corn meal agar they averaged 1.9 u. In the
Van Tieghem cell a hyphal strand was found to grow at the
rate of 2.8 u per minute or 1.7 mm per hour over a four-hour

pePlOd.

The homothallic condition of Pycnidigphora dispersa

 

could be seen in the single Spore isolations. In all fifty
isolations the ascocarps were produced as abundantly as in
the original culture.

When grown on corn meal agar the colony was thin,
Spreading, whitish, or translucent, submerged and superficial
with little aerial hyphae. After the pycnidia were produced
the surface of the colony had a slimy appearance because of
conidial production. As the colony aged the blackish
cleistothecia developed, scattered or dispersed, throughout

the medium and gave the colony a Speckled appearance.

..

 

59

Upon potato dextrose agar the total characteristics of
the colony were very similar to those found in cultures on
corn meal agar except that the growth was more dense, the
colony color was a dull gray to buff, and more aerial hyphae
were produced. The slimy appearance was lacking since the
aerial hyphae covered the pycnidia. Cleistothecia were r
similar in appearance, but larger and more abundant.

Germination of the oblong conidium (Pl. IV, Fin. 8)
started almost immediately after placement on the agar.

This was in the form Of a swelling of the Spore (Pl. IV,

 

Fig. 9). In three to four hours the Spore was nearly glo-
bose at which time a small protrusion develOped on the
surface at one end much as the yeast cell produces a bud
(Pl. IV, Fig. 10).

The bud elongated and at the same time a second bud
usually began to develOp on the Opposite side although in
many cases the develOpment of the second bud was delayed
until the first germ tube was well develOped (Pl. IV, Figs.
10-13). In one case a third germ tube was seen to deveIOp
from the Spore (Pl. IV, Fig. 12). Branching occurred at
any time but seemed to delay until the tube reached consider-
able length. Hyphal deveIOpment from a conidium was the

same as from the ascospore (91. IV, Figs. 1h and 15).

6O

Pycnidial DevclOpment

The small osticlate pycnidia were glabrous, varied
from globose to irregular-elongate in shape, and were 26-78
x 23-16h u on potato dextrose agar and 26-53 x 26-95 u on

corn meal agar (Table 12).

41-“;—

.,~ trad-7- --

During the develOpment of the imperfect or pycnidial
stage, the primordia could be Observed within the first ?
2h hours after inoculation Of the agar and mature pycnidia '

within the first 36 hours. All stages of deveIOpment from

 

mature pycnidia on Old mycelium to beginning stages on the
younger mycelium, could be seen even in a small sector Of a
colony. They were produced in moderate abundance primarily
along the agar surface, but in the very young colonies
pycnidia would be produced within the agar. The pycnidial
primordia were initiated by the cutting-out of several short
cells along a hyphal strand. This hyphal strand was either
a primary hypha (Pl. V, Figs. 23 and 24) or a secondary hypha
(P1. V, Figs. 26, 27, and 31), but more commonly the latter.
One or two of the center cells Of this initial then
lmecame enlarged (Pl. V, Figs. 23 and 2h), underwent two or
tflmree transverse divisions, and gave rise to a three- to
six-celled structure (pl. V, Figs. 25 and 26). This
structure, by continued swelling, and by division in all
Iiianes, formed a roundish mass with very few or no hyphal

lxranches (Pl. V, Figs. 27-29. 31—33). As this mass continued

to enlarge the upper portion, because 0
protruded slightly as a short rostrum. This was the pri-
mordium which became a flask-shaped pycnidium by the
formation of a small ostiole around the apex. The walls of
the cells around the ostiole and a few adjacent cells became
brown, thus giving the nearly colorless pycnidium a brownish
appearance. As soon as the ostiole appeared conidia were
exuded out over the surface of the pycnidium (Pl. V, Figs.
30, 33-3h)-or accumulated as a sizable drOplet at the apex
of the pycnidium. In any case the mature pycnidium origin-
ated from a single hypha.

Certain variations in pycnidial deveIOpment occurred.
Pycnidia with two or even three ostioles were commonly
observed. This, perhaps, was due to either the activation
of a large number of cells in continuous series, or to the
deveIOpment of two or three initials very close together
on the same hyphal strand. In only one instance was pyc-
nidial deve10pment observed to be compound meristogenous.
This occurred when a considerable amount of aerial hyphae
grew out of a small portion of infected plant tissue that
had been placed on water agar. On these hyphae develOped a
number of pycnidia which were darker in color than those
described above and, on micrOSCOpic examination, appeared to
'have been derived from two to four hyphal strands that had

been growing side by side.

 

62

The hyaline Conidia were produced on simple, extremely

short conidiOphores lining the inner portion of the pyc-
nidium (Pl. IV, Fig. 21). These conidia filled the pyc-
nidial cavity and at maturity were forced out in drOplets
that had a milky appearance and gave the surface of the
agar around the pycnidia a slimy consistency. The conidia
were oblong, very small, l.5-3.h x 3.1-h.3 u on potato
dextrose agar and 1.3—3.0 x 2.6-h.8 u on corn meal agar,

unicellular, and hyaline (Table 12). These spores were

produced in abundance.

Cleistothecial Development

The deveIOpment of the sexual reproductive or perfect
stage was initiated within the first hB to 60 hours after the
inoculation of the agar and resulted in a typical cleisto-
thecium. As in the case of the pycnidia, cleistothecia were
produced in abundance and, often, several stages of develOp-
.ment could be observed in a single sector of the colony.

The first Cleistothecial initials appeared in a zone of the
colony where the pycnidia were just reaching maturity and

were produced under the surface of the agar. As the colony
aged, cleistothecia seemed to arise at any level in the medium.

The cleistothecial initial was observed as a swelling of
came to five cells within a submerged primary hypha (Pl. VI,
Fi¢§. 35). Morphologically it could not be distinguished

fauna a pycnidial initial on a primary hypha. At no time

. aflghm LIN-PEW‘

were cleistothecia observed to develOp in the secondary
hyphae. The position in, or on, the medium, however, did
indicate which would be formed. Even so, as pointed out
above, pycnidia occasionally were produced submerged in the
very young cultures.

Enlargement and cell division followed in three planes.
At a very early stage hypha-like structures appeared in fair
abundance and were scattered over the surface of the develOp-
ing mass (Pl. VI, Figs. 36-38). They branched and often
fused with each other or with neighboring hyphae. The
function of these branch-like structures was not definitely
ascertained. It is suggested that they functioned as tri-
chogynes because they seemed to as devoid of cell content by
the time that the cleistothecium reached its maximum size,
and even showed some evidence of breakdown. The cleisto-
thecial primordium continued to enlarge by cell division
into a globose structure (pl. VI, Figs. 39-h3). Even at
Inaturity the origin of the cleistothecium from a single
lryphal strand was still visible (pl. VI, Fig. h2).

In four to six days after the initial appeared the
structure began to darken and the outer cell walls became
dark brown and distinct (Pl. VI, Fig. h3). The young
cleistothecial wall consisted of two layers. The outer
Ilayer'was dark brown and one cell thick. The inner layer
was parenchymatous and often several cells in thickness.

unris inner layer gradually decreased in thickness as the

_ um." axfihmflgi fang w

cleistothecium became older so that at maturity only the
outer layer remained. The ascocarp was dark brown to black
in color, more or less glabrcus, globose (Pl. VI, Fig. MA),
and measured 126-700 u on potato dextrose agar and 60-255 u
on corn meal agar (Table 11).

The exact way in which the ascogonium arose was not
determined. The cleistothecial primordium consisted of a
solid mass of cells, parenchymatcus in nature. Once asci
began to appear the inner portion of the fructification
became hollowed out, apparently by breakdown of the central
cells. This breakdown progressed as the asci develOped.
Globose asci were produced by crozier formation (Pl. IV,
Figs. 16-20) and appeared to rise in a Spiral-like manner
on the ascogenous hyphae. Each ascus was supported by a
very short stalk-cell which may have functioned as part of
the ascogenous hypha. These asci were not produced in a
hymenial layer but were scattered throughout the fructifi-
cation cavity by the continued growth of the ascogenous
hyphae.

The asci were globose, with 32 ascOSpores appearing
simultaneously in each ascus. When the aSCOSpores matured
the ascus wall evanesced, but the Spores remained conglobate
(P1. VI, Fig. MS). When the cleistothecium was still young,
‘but with mature Spore balls, the cluster of Spores did not

'break apart readily when pressure was applied to the slide

65

under the micr0800pe. But as these spore balls aged they
broke up more and more readily. Asci and Spore balls measured
10.5-13.0 u on potato dextrose agar and l0.0—1h.§ u on corn
meal agar (Table 11).

The aSCOSpores (Pl. VI, Fig. he) were oblong-reniform,
simple, light brown, and small, 2.0-2.9 x 2.3-5.3 u on
potato dextrose agar and 2.1-2.9 x 3.5-5.2 u on corn meal

agar (Table 12).

. $3564.11 I

66

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Hm.m m:.m ~m.m mm.m mm mm Suva: asset:
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.«.2.o .a.n.m .«.z.o .a.a.a o.¢.2.o m.a.a.a
opoamoom< Edavficoo Edaefizohm

 

 

“Sam: 55.50 20 m8 Z.
nae meozmg axommoome mzq .szaHzoo .ZbanHzowm ao smazzpm

NH mqmfie

 

. .. . '. ...VCI, ..—~ ”.1 V..II

.iunl I . IIV.‘

 

 

 

 

10“
P13a. 1-7, Alcoa oro palliation: 1) aaooaporaa: 2) apm n11
braann3 coon: 35’ protrusion or bulbous aw0111n3; h.) budd1n3
out or 301-- tnboa; 5,6,7) “Manon and branching of 301‘ tuba.
F13a. 8-15. Conidia: germination: 8) oonidia: 9) «011133 or
aporoz 10) budd1n3 out of 3am taboo: 11,12,13.1h.15). 01on3a-
tion and branching of 30m taboo.
113a. 16-20, Aaoua formation: 16.17.18) oroaiar formation;
19a,20) young asci; 19b,o,d) naturism not.
P13. 21, Cross notion of a pycnidim 121031113 oonidia and
oonidiophoroa.

P13. 22, Paronohyna call or Altar atom panatratod by a hyphal
atrand: a)hoat. «11.; b) hypha.

" \ a" -. .
”I ‘ITI I] I | I
Pics. 23-31;, Sts3os in tho loristogonous dovoiop-cnt or pycnidia:
23-25 ens-n, two- and tour-collod sta3os rospoctivoly on
rimry hyphao; 2 ) throo-oollod sta3o on a socondary min;
-30) sorios of sta3os in tho dovolop-ont of a single

pycnidia on a soccnd hypha; 31-311.) sorios of sta3os in
tho dowlopnont or snot r‘ pycnidiu- on a soccndary hypha.

 

 

 

mnmmmm ”’ ‘ f

113s. 35-h3, Sorios or sta3os in tho dovolcp-ont of tho
c1ois::thocia1 prinordiul on a sin31o primary hypha
’18.

balls.

0
, A crushod aataro o1oistothsciu- and scattorod spora-

F13. hS, Hi y Iagniriod cleistothecial wall and a

sporo-ball. F13. h , Ascosporos.

 

DISCUSSION F PYCNIUIIVHCRA QISPERSA

Rycnidiophcra has been tentatively placed in the ASper-

 

gillaceae (Eurotiaceae of many authors). Clements and Shear
'(ll) describe the family "Eurotiaceae" as: "Mycelium abundant r
superficial or innate, usually saprOphytic, mostly straight-
walled and without hyphOpodia or Spines; perithecia typically
on the mycelium, the wall usually parenchymic and membranous,

consisting of polygonal plates as a rule, breaking up gener-

 

ally or at the tip when mature, ostiole present only in

Micrascus, appendages present or lacking; asci typically in

 

corymboid clusters on branched hyphae, these rarely short
and approaching the umbelloid grouping, several to many,
globose to clavate, few-, rarely many-spored; paraphyses
regularly lacking; Spores various." This is in agreement
with other mycologists (7, 18). Based on this delineation,

PycnidiOphora is a member of this family.

 

Confirmation of this placement of Eypnidigphora was

 

made by Dr. M. P. Backus.l This conclusion is best expressed
by quoting with permission, from a letter dated July 6, 1953

received from Dr. Backus: "I have been studying your fungus

 

1. Following the eXperimental and morphological studies
detailed in this paper, and to either confirm or refute the
idea that an undescribed organism was involved, cultures
were sent to Dr. Myron P. Backus, Professor of Botany,
University of hisconsin, Madison, Wisconsin.

72

off and on over the past two weeks and must report that I
never sew anything line it and know of no genus into which
it would fit. I agree with you that it must fall in the
Aspergillaceac. ..... It certainly looks as if you have
something new to science here, and it is all the more

interesting that it is a path03en."

QT“

It has been shown in the previous section that the

fructification of 3. disoersa arises from one or two adjacent

nxwxuxb‘mj. 2 J

hyphal cells by continued cell division. "Since this process

is a true three dimensional cell division, ..... the result

f"

is a true parenchymatous tissue and not a pseudo-parenchy-
matous matrix as in many fungi." The early develOpment of
the cleistothecial body of g. disEersa is similar to the
early deveIOpment of the perithecial body of §porormia
bipartis Cane as it is figured and described by Page (3h).

 

The Sporormia perithecial initial is considered by Ggumann

 

(18) to be stromatio.

The modern tendency, stimulated by Miller (31), is to
revise the classification of the Ascomycetes, particularly
the Pyrenomycetes, to embrace the characters of ontogeny as
well as the mature ascocarp. Ggumann (18) points out that
in the ASpergillaceae sexual reproduction initiates the
formation of the fructification and usually takes place by
means of special cepulation branches. Since the cleisto-
thecial primordium of PycnidiOphora disperse is considered

to be stromatic, the placement of the genus in the

73

"
ASpergillaceae may be questioned. However, Gaumann says

that in Penicilliquis, a form included in the Aspergill-

 

aceae, the fructification develops vegetatively. Therefore,
until a Specialist of the group further defines the family,
pgycnidiQQhorg should be included in the family.

In E. disperse the sexual process probably takes place
in the stromatic-like cleistothecial primordium, out this
must still be studied and worked out. It is suggested that
the thin hypha-like structures that grow out from the young
cleistothecial primordium function as trichogynes. Clari-
fication of this, as well as its taxonomic position, will
depend on future cytological studies of this organism.

The most unusual feature of this organism is the
asexual stage. No other member cf the ASpergillaceae is
known to form pycnidia in the imperfect stage. The deve10p-
ment of the pycnidium of E. disoersa was typically simple
meristogenous. This deve10pment was similar to the simple
meristogenous develOpment of 222mg Species as reported by
Kempton (26).

Although this organism has not been described before
it is possibly a common soil inhabitant that has been over-
looked in the past. A fellow student1 recently isolated a
similar organism from a soil sample obtained from a lawn in

the city of East Lansing.

 

1. Ralph Collins, Michigan State College, East Lansing,
Michigan.

 

Following Koch's postulates PycnidiOQhora disperse has

 

been shown to cause damping-off of Phlox, Aster, and Lily
seedlings under laboratory conditions. Further eXperi-
mentation, particularly under greenhouse conditions, is
desirable in order to establish the host range, the disease
producing potential, and the environmental requirements of

this organism.

 

SUMMARY

A study was conducted in which seeds of 1h ornamentals
were treated with certain of ten fungicides in various
combinations in a series of field and greenhouse trials.

In one or more trials significantly better seedling ;
emergence occurred when seed protectants were used on seeds I

of Aster, Bachelor Button, Calendula, Cosmos, Four O'Clock,

 

Morning Glory, Nasturtium, Phlox, Stock, Sweet Pea, and
Zinnia.

Marigold was the only ornamental on which seed pro-
tectants failed to give some measure of protection against
damping-off. Only limited protection was apparent on
LarkSpur and Dahlia seed. -

Post-emergence damping-off was not controlled by the
seed protectants in these eXperiments.

An organism, with a pycnidial imperfect stage, was
isolated from a diseased Phlox seedling. This organism, by
virtue of its perfect stage, was classified in the ASper-
gillaceae as that family is presently constituted.

This organism was shown to be pathogenic and caused
damping-off.

A new genus and Species, Pycnidioghora diSpersa, were

preposed and described to embrace this organism. The life

76

history and morphology were studied on corn meal agar and
potato dextrose agar. Conidium and ascospore germination
and hypha deve10pment were traced. Pycnidial develOpment
was found to be simple meristogenous and the cleistothecium
was observed to arise in a similar manner from a few inter-
calary cells in a single hyphal strand. The 32-3pored asci,
which were scattered throughout the cleistothecial cavity, ;

were produced by crozier formation.

 

l.

2.

3.

h.

9.

10.

11.

12.

LITERATURE CITED

Alexander, Lo Jo, Ho Co Yomg, and Co Mo Kiger’, 1931.
The causes and control of damping-off of tomato seed-
lings. Ohio Agr. Exp. Sta. Bull. h96:1-38.

Atkinson, G. F., 1895. Damping-off. New York (Cornell)
Agr. Exo. Sta. Bull. 9h:233-272.

Baker, K. F., l9h7. Seed transmission of Rhizoctonia
solani in relation to control of seedling damping—off.
FEyEOQath. 37:912-92h.

 

Balfe, I. G., 1935. An account of sclerote-forming
fungi causing disease in flatthiola, Primula, and
Eblphinium in Victoria. Proc. Roy. Soc. Vict. #7:
369-356.

 

Eaten, w. D., 1939. Formulas for finding estimates
for two and three missing plots in randomized block
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Beaumont, A., 1950. Diseases of China Asters.
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Bessey, E. A., 1950. Morpholo and taxonomy of fungi.
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Bolley, H. L., 1897. New studies upon the smuts of
wheat, oats, and barley, with a resume of the treat-
ment experiments for the last three years. N. 2. 553.
E. m. Bull. 27:109‘16’4. -

Chilton, St. J. P.. D. C. Bain, and L. H. Person, l9u3.
Effect of seed treatments on stands of ornamental
plants. (Abstract in Proc. Lg. Acad. Sci. 7:36).

Clayton, E. E., 1928. Increasing stands from vegetable

seeds by seed treatment. New York (Geneva) Agr. Exp.
Sta. Bull. Ssuzl‘léo

Clements, F. E. and C. L. Shear, 1931. The genera of
fungi. New York: H. w. Wilson Company. '-_

Coons, G. H. and D. Stewart, 1927. Prevention of

sezdling disease of sugar beets. Phytopath. 17:259-
29 o

 

_.i_. m .‘l

 

13.

1h.

15.

16.

17.

18.

19.

20.

21.

22.

23.

2h.

25.

78

Dimock, A. w., 1941. The Rhizoctonia root rot of
annual stocks (Matthiolafiincana). Phytopath. 31:
87-91.

 

 

 

Dimock, A. w., 1951. Semesan drench for Rhizoctonia
control. New York State Flower Grs. BuII. 60:5-7.

(Abstract, Rev. App. Mycology 30:EI, 1951).

Doran, w. L., 1938. Germination of seeds and damping-
off and growth of seedlings of ornamental plants as
affected by soil treatments. Mass. £33. §_p.‘§g§.
Bull. 351:1-uuo

Doran, w. L., 19h6. Diseases of plants caused by soil
infesting organisms, with particular attention to
control measures. Annual Rep. Mass. Agr. E 2. Sta.
Bull. h36zl9-20.

Dunlap, A. A., 1936. Seedling culture in sand to prevent
damping-off. Phytopath. 26:278-28h.

 

Gaumann, E. A., 1952. The fun 1. New York: Hafner
Publishing Co. (English rans ation by F. L. Wynd).

Haenseler, C. M., 1928. Effect of organic mercury
seed treatments on germination and yield of peas.

a- .1- lap Eas- .512- 5.22- Esa- u8=232-238-

Hartley, C., 1921. Damping-off in forest nurseries.
Ho g. 20 A. Bull. 931841-99.

Horsfall, J. C., 1930. Combating damping-off of tomatoes
by seed treatment. New York (Geneva) Agr. E 2. Sta.
81111. 586:1-22.

Horsfall, J. C., 1938. Combating damping-off. New
York (Geneva) Agr. Exg. Sta. Bull. 683:1-h6.

Horsfall, J. C., A. G. Newhall, and C. E. F. Guterman,
193a. Dusting miscellaneous seeds with red COpper
oxide to combat damping-off. New York (Geneva)

55;. 13352. 33. Bull. emu-39."— """""'

 

Jensen, J. L., 1888. The prOpagation and prevention
of smut in cats and barley. Jour. Roy. Agr. Soc.

England, Sec. 2, 2uz397-h15.

 

Kadow, K. J. and H. W. Anderson, 1937. Damping-off
control: An evaluation of seed and soil treatment.
Ill. Agr. Exp. Sta. Bull. h39:291-3h8.

26.

27.

28.

29.

30-

31-

32-

33.

3h-

35.

36.

37.

79

Kempton, F. E., 1919. Origin and develOpment of the
pycnidium. not. Caz. 68:233-261.

Lammerts, w. E., 19h0. Ethyl mercury iodide - an
effective fungicide and nemacide. PhytOpath. 30:

33h-338.

Leukel, R. w., 1936. The present status of seed treat-
ment with Special reference to cereals. Bot. Rev.

2zh98-527.

Leukel, R. w., 19h8. Recent development in seed
treatment. Bot. Rev. 1h:23S-269.

Linnasalmi, A., 1952. Damping-off on herbaceous vege-
tables and ornamental plants grown under glass in
Finland. Ann. (bot.-zool.) Soc. zool-bot. fenn.
Vanamo, seat? bot. 26:1-120.‘TFinfiiSh summary).
(ABSEract, R31. 522' Mycology 32:h12-hl3, 1953).

Miller, J. H., 19h9. A revision of the classification
of the ascomycetes with Special emphasis on the
pyrenomycetes. Mycologia h1:99-127.

' fifi??;‘~; We ’5- L fi—Lj *~‘-'A'r- H. .... ‘~. 3; '1’ :7
. ‘ ‘
‘ :

Nema, K. G. and.K. A. Mahmud, 1950. Damping-off of
Brinjal seedlings caused by Rhizoctonia (Corticium)
solani Kuhn. Mag. A r. Coll. Na ur 25:1-2.
(Abstract, Rev. App. ycoIogy 30%360, 1951).

 

Newhall, A. G. and B. Lear, 19h8. Soil fumigation for
fungus control with methyl bromide. Phytopath. 38:

38-h3-

Page, w. M., 1939. Contributions to the life history
of certain c0p0philous fungi. Trans. British Mycol.
Soc. 23:253-268. ""‘

 

Person, L. H. and S. J. P. Chilton, l9h2. Seed and soil
treatment for the control of damping-off. La. Agr.
Exp. Sta. Bull. 389:1-16. ‘-—

Prevost, I. B., 1807. Memoirs sur la cause immediate
de la carie ou charbon des bles et de plusieurs
autres maladies des plantes. (English translation
by G. W. Keitt. Phytopath. Classics 6, 1939).

 

Sharma, 0. P. and K. A. Mahmud, 1950. Damping-off of
Antirrhinum majus L. caused by Rhizoctonia (Corticium)
soIanI KEEn.. Mag. A r. Coll. Na ur 25:57-u8:
(Afistract, 331. App. Tycology : -232, 1951).

 

 

353 .

no.

#1-

“2o

LL3-

1+5.

A60

h7.

80

Srivastaya, H. C., 1951. Damping-off in Hollyhooks.
Sci. & Cult. 17:91-92. (Abstract, Rev. App. Mycology

BI?328’ Ig'fi)o

 

 

Srivastaya, H. C., 1951. Damping-off in Saponaria.
Sci. g Cult. 17:226-227. (Abstract, Rev. Aoo.
myaoiogy‘SI:eos. 1962)-

 

,Stoddard, E. M. and G. A. Zentmyer, 1950. Control of

damping-off with 8-Quinolinol. Plant U13. Reporter

3u:236-237. t

Stoutmeyer, V., C. Reps, and A. Close, l9hl. Sphagnum
for seed germination inhibits damping-off losses 9
on unsterilized soil. Nat. Hort. Mag. 20:111-120.

 

 

 

i
Taubenhaus, J. J. and A. L. Burkett, 1937. The effect .
of chemical seed and soil treatments on damping-off E
and other diseases. Fiftieth £22° §22° 12§° figs. *_
Exp. §22'9 1-117.

 

Tilford, P. E., 1931. Control of damping-off of
flower seedlings. Ohio Agr. EXp. Sta. Bimonthly
Bull. 152:167-175.

 

 

 

Tisdale, W. B., A. N. Brooks, and G. R. Townsend, l9h5.
Dust treatments for vegetable seed. Fla. Ag . EXP“
Sta. Bu110 “1331-320

Walker, J. C., 19h8. Vegetable seed treatment.
BOto Rev. lu:588'6010 ~

Walker, J. C., 1950. Plant ethology. New York:
McGraw-Hill Book Company, no.

 

Wilson, J. D. and P. E. Tilford, 1933. The use of
formaldehyde dust in growing seedlings. Ohio Agr.
Exp. Sta. Bull. 520:1-h0.

 

APPENDIX

an
iv

3% 103380405060708090 momma
Non-treated

Pavson

Arasan

Spe rgon

STAND AND memos, PERCENTAGE OF PIANTED. Viability 61$

 

 

Fig. 1. Aster (Crego). Field, 1951.

ilpaoaoesgsaaagso mmm
* Non-treated

Arasan

Hogan

Spergon
STAND AND mazes. PERCENTAGE or SEED PLAN'm, Viability 61%

Pig. 2. Aster (Crego), Greenhouse, December 1951.

 

 

 

 

$19 29394959697089 9910116101133
- 3‘“ Non-treated
,._‘ -. m Arasan
, - , L“ Orthocide 406
' ‘ ' “\\\\‘ Vancide 51
‘ \\\\\\\:J N. I. Ceresan
-;* - A\\\‘ 0 a. c 5400
'A\\\‘ Phygon
\\\ Bed Copper Oxide
*n‘ Spergon

 

STAND AND memos, PERCENTAGE or PLANI‘ED, Viability 969%
fig. 3. Aster (Crego), Greenhouse, March 1952

xipmsggospepzospgo mmm
\\\\“ . Non-treated
Phygon
Orthocide. 75
Arasan S!

s ‘ . Arasan
STAND AND mamas, mmm or sun mm, Viability 911%

Big. 4. Aster (herican Hearty). field, 1952

 

   

 

 

_ _ -.—~ _- “-7.6

 

$19§33O49§3607DQ$ 311mm...

Non-t rested
Phygon
Arasan

Spergon
STAND AND memos. WAGE or m, Viability 87%

mg. 5. Calendula (Double Orange King). Field, 1951.

 

filozosoqogipleomeog: mcicm

Non-t rested
Phygon
Arasan

. Spergon
sTAND AND memes, mm or m PLAN-m, Viability 87%

1'15. 6. Calcium]; (Double Orange King), Greenhouse. December 1951.

 

$198.932495969796999 momm-
Non-treated
Phygon
08.05400
Arasan
Orthocide75
ArasanSl'

Spergon
STAND AND mum, mm or mm mm, Viability 39%

Fig. 7. Calendula (Double Orange King) , field, 1952.

 

filpapaowfipaozogao mum
S Non-treated
u Phygon
s Vancide 51
in G 8. c 5400
t‘ Arasan
N Bod Copper Oxide
c D. I. Ceresan

\w 313018011
STAND AND males, manner or sun PLANPED. Viability 95%

1'18. 8. Calendula (Double Orange King), Greenhouse, January 1952.

 

 

IC—fimwfig‘?""€
I H i. I

% 10 so 30 4o 50 so VolstGicmE
Non-treated

Phygon
Orthocide 75
Arasan
Arasan SF
Spergon
STAND AND memos. momma 0F SEED PLANTED. Viability 83%

Fig. 9. Bachelor Button. Field, July 1952.

 

5% 10 so so 49 so so 7p[FUNGICIDE__
Non-treated.

Orthocide 75

Hweon

Arasan SF

Arasan

Spergon
STAND AND MGENCE, PERCENTAGE OF SEED FLAME, Viability 83%

Fig. 10. Bachelor Button. Field. September 1952.

A 1.03 so 49 5.0 so 79 [ momma
Non-treated
Phygon
Arasan
Spergon
STAND AND nmscmcs, PERCENTAGE or SEED PLANTED. Viability 93%

 

Fig. 11. Cosmos (Sensation), Held, 1951.

A 10 2.0 3.0 49 50 6.0 L0] momma
Non-treated
Arasan SF
c a c 5400
Orthocide 75
Phygon
Arasan
Spergon

STAND AND W01. mamas or SEED HANTDD, Viability 85%

 

Hg. 12. Cosmos (Sensation). Field, 1952.

 

7% 19293241059 sprelmrcnm

Non-treated.
Arasan

 

Spergon
STAND AND EMERGENCE. PERCENTAGE OF SEED PLANTED, Viability 81%

Fig. 13. Dahlia (Unwin's Dwarf Wbrid). Field. 1951.

93 19 20a) ab so so vosplmNGICIDE
Non-treated
Arasan SF
Hvson
Arasan
Spergon
Orthocide 75
c a c 5400

STAND AND BERGENCE. PERCENTAGE or SEED PLANTED, Viability 90%

 

Fig. 14. Dahlia (Unwin's Dwarf Wbrid). Field, 1952.

5% 10 2139 to so so 79 ECLPUNGICIDE
Non-treated.
Arasan

Spergon
STAND AND BERGENCE. PERCENTAGE 01" SEED PLANTED. Viability 81%

 

Fig. 15. Four O'Clock (Mel of Peru), Field. 1951.

filoapso4osoeovoeo|mNGICIDE
Non-treated
Orthocide '75
Arasan
Spergon
PIN/eon

C & C 5400
STAND AND IMERGENCE. PERCENTAGE OF PIANTED, Viability 90%

 

Fig. 16. Four O'Clock (Mel of Peru). Field, 1952.

 

75 19 20 39 49 Sp 610 | FUNGICIDE

Non-treated.

Phygon

Arasan

C a. c 5400

Spergon

STAND AND EMERGENCE, Pmcml‘AGE OF SEED PLANTED, Viability 80%

rig. 17. Iancspur (Giant Imperial). Field. 1951.

 

a; map so 49 59 69 Immcxcm
Non-treated

ngon
Arasan
Spergon
c a. c 5400
STAND AND mmcn, PERCENTAGE OF SEED PLANNED, Viability 60%

Fig. 16. Iarkspur (Giant Imperial). Greenhouse. December 1951.

9‘ wwwsolw

Non-treated.
Arasan

Spergon
c a. c 5400
Orthocide 75
8°11
STAND AND memcz, momma: or W, Viability 84%

Fig. 19. Iarkspur (Double Mixed), Field. 1952.

%10a030495050701

RING-1C IDE

Non-treated
Phygon
Snergon
Arasan

C & C 5400

STAND AND DmeCE, PERCENTAGE OF SEED mm, Viability 74%

Fig. so. Marigold (Harmomr Dwarf), Field. 1951.

fixozoapwaoepvol

FUNGICIDE
Non-treated.
Arasan
Phygon
Spergon
C & C 5400

 

STAND AND WGMCE, MOW]: OF SEE PLANTED. Viability 84%
Fig. 21,. Marigold (Hameny Dwarf). Greenhouse, December 1951.

xxoapsowsosozol

FUNGICIDE
Non-treated
C & C 5400
HD'gon
Arasan
Orthocide 75
Spergon

STAND AND WGH‘ICE, FNMAGE 0F S.PLAN'1‘ED, Viability 87%
Fig. 22. Marigold (African). Field. 1952.

St. I 34. ,9! riffs...

A

l02030$050$70 8999|FUNGICIDE
Non-treated
Arasan
Phygon

Spergon
STAND AND FMERGENCE. PERCENTAGE OF SEED PLANTED. Viability 61%

Fig. 28. Morning Glory (Heavenly Blue), Field, 1951.

51,02,039 4959 6979 so aolmoxcm
Non-treated

Hygon
Arasan
Orthoc ide 75

Spergon
STAND AND EMERGENCE. PERCENTAGE OF S- MED. Viability 56%

Fig. 24. Morning Glory (HeavenJy Blue). Field. 1952.

31.0298949596979a099lmmmm
Non-treated
Spergon

Arasan

STAND AND BERGENCE, PERCENTAGE OF SEED PLANTED. Viability 82%

 

 

Hg. 25. Nasturtium (Dwarf Choice). Hold. 1951.

filoaosoioeoso'zoepgolmorcm
Non-treated
thgon
Orthocide '75
Arasan

Spergon
STAND AND EMERGENCE, BERGENTAGE 0P SEED PLANTED, Viability 60%

 

Fig. 26. Nasturtium (Glor. Gleam Hybrid), Field. 1952.

 

$ i0 30 so 40 So {so 70] FUNGICIDE
Non-treated
Arasan SF
Orthocide 75
Arasan

Phygon
STAND AND MERGENCE, PERCENTAGE OF S- PLANTED. Viability 925%

Mg. 27. Zinnia (Giant of California), Field, June 1952.

Sioaoeoioso 6020] mmcm:

Non-t reated
Orthocide 75
Arasan SF
Arasan

Phygon
STAND AND EVERGMCE, PERCENTAGE OF SEED PLANTED, Viability 92%

Fig. 28. Zinnia (Giant of California). Field. September 1952.

 

 

 

a” n. I.
i L LEC.III

x

 

 

 

 

 

S 1o so So 4o so so fromgofl so 100 mommy:
u Non-treated
NI N. I. Ceresan
In.“ Phygon
\ y\;| Vancide 51
; K \ \\l c 8: C 5400

 

  

L‘

 

Bed Copper Oxide

 

 

 

 

 

 

 

 

 

 

 

Hg. 31. Sweet Pee. Held. 1952.

5“ Arasan
mu Spergon
STAND AND EMERGENCE. PERCMAGE or PLANTED, Viability 92%
Fig. 29. Sweet Pea, Greenhouse. Jammy 1952.
at io 20 so 42 so so 79 so so 100 micm
L“ Non-treated —
X \\ \ \ \‘1 Phygon
\\\\\\\VJ N. I. Ceresan
n‘“‘ C a. c 5400
a.“ Orthocide 406
‘ Vancide 51
\\ \ \I Arasan
m Red Copper Oxide
an“ Spergon
STAND AND BERGENCE, momma or SEED mm, Viability 92%
Fig. 30. Sweet Tea. Greenhouse, February 1952.
5 1o 2o 3o 40 so so 19 go so 190 mum
L.“ Non-treated
.\\\\‘ argon
n\\\V N. I. Ceresan
I.“ Orthocide 406
L“ Arasan S!
IA\“ 0 at C 5400
u“ Vancide 51
STAND AND mom. PERCENTAGE or SEED PLANTm, Viability 30$

 

Alpgpspipsgepvpepso

FUNGICIDE

 

m
. E

u
‘5'

L“

1“

A.“
m‘

STAND AND MGENCE, PERCENTAGE or SEED PLANTED, Viability 93%

Fig. 82. Stock. Greenhouse, January 1952.

$193093°20595079Q099
I
IN-
INN
I
!
Ian:
I
NI
tN

 

 

Non-treated.

N. I. Ceresan
Ween

Vancide 51

Red. Copper Oxide
Arasan

C 8: C 5400

Spergon i

T.....,—..~______4-—r-a".~-i.-.
e' .. . 1. v .

WNGICIDE

Non-treated

C & C 5400
Arasan

N. I. Canaan
Red Capper Oxide
Orthocide 406
Vancide 51

Hiygon
Spergon

STAND AND ENERGENCE. PmCEITAGE or sun PLANTED, Viability 93%

Fig. 33. Stock, Greenhouse , Pebmary 1952.

 

  

1» 10 240 30 4Q 59 60 7,0 89 l'UNGICIDE
Non-treated
Orthocide '75
Arasan
‘ Spergon

STAND AND FMflGENCE , PERCENTAGE OF SEED

 

PLANTED, Viability 85%

Fig. S4. Phlox (Dmmondii), Greenhouse, Decxmber 1952.

$19@3040506070

_1 l A

m
K“
H

 

FUNGICIDE

Non-treated

N. I. Ceresan
Orthocide 406
Arasan

Red Copper Oxide
Spergon

Phygon

Vancide 51

STAND AND BERGENCE, PERCENTAGE 01' PIANTED, Viability 85%

fig. 35. Phlox (Dmnlnondii), Gremhouee. January 1953.1

'!

......

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A

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new ESE CNN

 

 

 

        

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