Sugar cane root disease in Cuba. Zonate foot rot of sugar cane

Material Information

Sugar cane root disease in Cuba. Zonate foot rot of sugar cane
Faris, James Abraham, 1890-1933 ( author )
Allison, R.V. ( author )
Place of Publication:
Washington, D.C.
Tropical Plant Research Foundation
Publication Date:
Physical Description:
1 online resource (94 pages) : illustrations


Subjects / Keywords:
Sugarcane -- Cuba ( lcsh )
Sugarcane -- Diseases and pests -- Cuba ( lcsh )
Caña de azúcar ( qlsp )
Caña de azúcar -- Enfermedades y plagas ( bidex )
non-fiction ( marcgt )


General Note:
Tropical plant research foundation. Scientific contributions, no. 4.-5
General Note:
Sugar cane root disease in Cuba is reprinted ... from Phytopathology, v.17, no. 2, February, 1927.
General Note:
Zonate foot rot of sugar cane is reprinted ... from Phytopathology, v.17 no. 2, February, 1927.
General Note:
At head of title: Cuba Sugar Club Experiment Station.

Record Information

Source Institution:
University of Florida
Holding Location:
University of Florida/IFAS, Everglades Research and Education Center
Rights Management:
This item is a work of the U.S. federal government and not subject to copyright pursuant to 17 U.S.C. §105.
Resource Identifier:
035875213 ( ALEPH )
1023810708 ( OCLC )
SB215 .T8 1927 ( lcc )

Full Text


Scientific Contributions, Nos. 4 and 5

Central Baragui, Provinwe of C:unn giiey, Cuba

4. Sugar Cane Root Disease in Cuba

Reprinted without change in pagination from PHYTOPATHOLOGY, Vol. 17,
No. 2, February, 1927

5. Zonate Foot Rot of Sugar Cane


Reprinted without change in pagination from PHYTOPATHOLOGY, Vol. 17,
No. 2, February, 1927

1927 1350 B Street, S.W.
Washington, D.C.




In English
i. Rainfall and Temperature of Cuba
2. The Sugar Cane Moth Stalkborer
3. A List of the Insects Affecting Sugar Cane in Cuba
4. Some Serious Sugar Cane Diseases Not Known to Occur in Cuba
5. Certain Grass Hosts of the Sugar Cane Mosaic Disease and of the
Corn Aphid Considered in Relation to Their Occurrence in Cuba

In Spanish
2. El Borer6 Perforador del Tallo de la Caiia de Azucar

Scientific Contributions
In English
i. Notes on the Economic Status of Certain Cuban Homoptera
In Journal Economic Entomology, Vol. 19, No. 1, pp. 99-106, 1926.
2. Faunistic and Ecological Notes on Cuban Homoptera
In Annals of Entomological Society of America, Vol. XIX.
No. 3, pp. 335-366, September, 1926.
3. Cold Chlorosis of Sugar Cane
In Phytopathology, Vol. 16, No. 11, pp. 885-891, Novem-
ber, 1926
4. Sugar Cane Root Disease in Cuba
In Phytopathology, Vol. 17, No. 2, February, 1927.
5. Zonate Foot Rot of Sugar Cane
In Phytopathology, Vol. 17, No. 2, February, 1927


Scientific Contributions, Nos. 4 and 5

Central Baragua, Province of CarmigUey, Cuba

4. Sugar Cane Root Disease in Cuba


Reprinted without change in pagination from PHYTOPATHOLOGY, Vol. 17,
No. 2, February, 1927

5. Zonate Foot Rot of Sugar Cane


Reprinted without change in pagination from PHYTOPATHOLOGY, Vol. 17,
No. 2, February, 1927



1350 B Street, S.W.
Washington, D.C.

[I eprinted froim l"In-Y''OPATHOLOGY, F ebruariy, 1927, Vol. XVI I, No. 2]



There has been much concern expressed by the cane growers of Cuba
over what has been referred to for some time as "root disease.'' In the
field it appears that this term has been widely applied to cane dying under
a great variety of conditions, in fact under practically any condition that
does not manifestly involve the above-ground parts of the plant structure.
This tendency to bring every malady affecting the under-ground parts of
the plant under the general term of "root disease'' or "root rot'' has been
confusing and in many cases has resulted in planters throwing land out of
cane over considerable areas because of a disease about which they know


FIa. 1. Successive stages in the death of cane affected with "root disease.''
1 Scientific Contributions No. 4, Tropical Plant Research Foundation. From the
Cuba Sugar Club Experiment Station, Central Baragud, Cuba.


nothing. However, it now seems that the disease in many of these areas is
due to one or more of the soil conditions discussed in the second part of this
report, and in several cases studies are being instituted by the planters to
reclaim some of this land.
Investigations have been in progress in many of the more important cane-
growing countries for many years, and everywhere the studies have been
uniform and emphatic in pointing out the necessity for proper agricultural
conditions for growing cane. In many cases what has appeared to be a
serious disease menace has disappeared when some adjustment has been
made in the matter of soil drainage, fertility, or cultivation. Owing to the
confusion created by referring to such a large group of primary causes of
disease as root disease, it seems desirable to briefly review the situation as
we have found it at the end of our first rear's work, with the hope that the

FIG. 2. Longitudinal section of the base of a cane stalk, showing characteristic foot rot
due to Melanconiln.

planters will study the failing areas in their fields in the light of this dis-
In order to analyze the root disease situation and to facilitate the loca-
tion of the initial weakening of the plants, the primary causes of the death
of the cane are considered as due in part to pathogenic factors and in part
to non-pathogenic factors.
The possible pathogenic invading organisms require further study for a
determination of their nature, habits, and probable spread, but cannot be
said, in the light of our present information, to be very serious factors upon
any of the considerable number of plantations visited.
The work upon this group of possible causes consists in the isolation of
probable primary invading organisms and determination of their capacities
for infecting healthy plants.


Plants dying of this complex malady exhibit certain rather marked
symptoms. The outer leaves first show signs of drying and rolling up, while
the inner leaves are still green. This is followed by rolling of the inner
leaves and death of the outer ones. This drying may continue until all of
the leaves are dry and the plant dies. In figure 1 is a series from a single
hill which shows a gradual progress from a slightly affected stalk on the
right (stalk 1) to one with leaves completely dry (stalk 4). The root sys-
tems of these stalks were poorly developed and the bases of the stalks them-
selves were found to be badly infected with the Melanconium species later
discussed. Such plants are not uncommon in many of the fields of Crystal-
lina cane in Cuba. These drying out changes may be brought about by any
cause which cuts off the water supply from the top of the plant. In various
parts of the Island, during both the wet and dry seasons, fields have been
observed which contained plants in all stages of drying out. Usually the
trouble is more conspicuous during the dry season, and any obstruction of
the water flow would be reflected in the lack of moisture delivered to the
growing parts at that time.
From the study of diseased cane plants in certain areas where decreasing
production was attributed to root disease, it became evident that a very
large number of these plants not only had diseased roots but also had de-
veloped what might well be called a foot rot (at the bases of the stalks).
Plants affected with this basal stalk rot have a zone of dying tissue extend-
ing from the base of the plant upward. In some cases it is this progressing
zone of diseased tissue which cuts off the water supply from the top of the
plant, even though the root system is quite well enough developed to supply
the needed moisture. There are several types of this basal stalk rot, at least
one of which shows many indications that it is primarily due to an invading
parasitic organism. This type of foot rot is described as zonate foot rot in
another article.2 The type under discussion here, pictured in figures 2 and
3, is associated with species of the fungus Melanconium, which proceeds
from the base upward in the stalk, with an advanced zone of infected
bundles, usually of a blackish color, extending through several internodes
of the stalk. Figure 2 shows longitudinal sections of the base of an infected
cane stalk with the blackened zone extending up one side. Figure 3 shows
the brownish woody stem bases in which the water-conducting strands have
been plugged up, thus preventing the functioning of the root system.

As soon as the first two months' preliminary survey of the cane root
disease situation in Cuba was finished, intensive work was begun upon the
2 FARIS, J. A. Zonate foot rot of sugar cane. PHYTOPATH. 17: 83-94. 1927.


fungi associated with these root and stalk rots. Isolations were made of a
very large number of fungi from diseased tissues. After study and identi-
fication, many of these were eliminated as probable causes of the malady
upon the grounds that they had been repeatedly experimented with by
other investigators and found to be harmless to healthy cane. Among the
fungi found in these tissues were two species of Melavconium; one of these,
M. ilian, which causes the ilian disease of sugar cane in Ha-awaii, had not
been previously reported from Cuba. It seemed quite probable that this
might be an active parasite infecting the cane plants, although its destrue-
tiveness in the Hawaiian fields is attributed by Lyon to the tight binding of
the leaf sheath of -the young plants, thus preventing the development of the
young shoots. The other, .-. sacchari, as is well known, causes the ever-pres-
ent rind disease. in view of its prevalence in these diseased plants, it seemed
worth while to make some inoculations with pure cultures of this fungus
and determine its pathogenicity. Since it was desired to follow the develop-
ment of the root disease more closely, further experiments were carried out
in order to insure infection in case neither of the Melanconiums proved to
be capable of infecting the healthy plants. In these tests the seed piece was


Fic;. 3. Bases of caine stalks infected -aith M'Ilanconeurn.


covered with an abundance of finely chopped roots and stalk bases of dis-
eased plants.
In connection with these experiments several different soils were used
in order to determine, if possible, the influence of soil type upon the develop-
ment of the disease. The soils were taken from spots where plants were
dying from the disease. These soils were placed in sacks 212 feet long and
about 8 inches in diameter. One portion of the soil was sterilized. Length-
wise through the center of the sacks wheh were to be sterilized was placed a
piece of rolled screen. This was done to facilitate sterilization but proved
unnecessary, as perfect circulation of the steam was secured without it.
Sterilization was done under six pounds steam pressure for three hours.
One series of plants was grown in the soil without treatment, and the other
series was planted in the same soil sterilized with steam.

FIG. 4. 1. Plants inoculated with Melanconium ilian. 2. Check, uninoculated. Soil I,
sterilized. No infection.

Method of Inoculation
In the case of M. ian and M. sacchari, the fungi were isolated in cane
plug cultures, cornmeal agar, and cane juice agar, and these pure cultures
multiplied in flasks. From these flasks blocks of one cc. were taken, placed
upon a stick of Crystallina cane which had been sterilized in mercuric
bichloride (1 to 1000) and rinsed in distilled water, and held in place by a
piece of filter paper. Each seed piece had three nodes, but the two end buds


were removed when the center one was inoculated. These seed pieces were
then planted in pots which were made by cutting gasoline cans in halves.

Soil Types Used
Four soil types were used in these experiments, and have been referred
to by number in the tables. Type I (Havana clay) represents a heavy,
ashy-gray to black, calcareous clay that passes down through calcareous
delay of a lighter color into cream-colored chalk at an average depth of ten
or twelve inches. In places, light-colored, slabby limestone occurs at shallow
depth and not infrequently is strewn over the surface in considerable quan-
tity, particularly where the topography is rolling. Where it is not too
shallow, this type ranks very high as a cane soil, giving good yields and high
sugar return under good cultivation. Type II, a deep red soil (Matanzas
clay), derived from "dog-tooth'' limestone such as is found in large areas
in the provinces of Havana and Matanzas, is also an excellent cane soil.
Type III (Oriente clay) is a very heavy black soil which, characteristically,
is immediately underlain by coe6. This is ranked as a rather poor cane soil.
Type IV (Limones clay) is a heavy, purplish-red clay, apparently formed

TABLE 1.-The effect of inocalating Crystallina cane with Melanconiim ilian. Cane
planted March 6, 1925, and harvested January 1, 1926

Type of soil and Inoculations No. of Results
treatment plants
I. Sterilized Inoculated 56 Free from root and stalk rots
(10 Uninoculated 6 do
Unsterilized Inoculated 6 do
do Uninoculated 6 do
II. Sterilized Inoculated 9 do
do Uninoculated 9 do
Unsterilized Inoculated 9 do
do Uninoculated 9 do
III. Sterilized Inoculated 9 do
do Uninoculated 4 do
Unsterilized Inoculated 4 do
do Uninoculated 4 do

from the breaking down of serpentine rock. In this the topsoil, upon dry-
ing, breaks into hard clods. This passes into pinkish red to red clay at 4-6
inches and into parent material (undecomposed or partially decomposed
serpentine and other rock material) at 1-4 feet. It is only a fair cane soil
but can be brought to fairly high production by good cultivation and the
application of eachaza (filter-press cake).


Results with Melanconiun ilian
In no case did 31. ilian prove to be capable of infecting the growing cane
plants, even when the organism was put over the buds at planting time. It
should be pointed out that this is but one of the organisms found associated
with root and stalk rot in the field. The plants were kept growing vigor-
ously, as will be seen from the size of those in figure 4. A portion of the
plants which had been inoculated with 31. iliau was cut to the ground sur-
face and these plants will be carried to the first ratoon. The pots are very
small and the soil is filled with a dense mat of roots, so the plants are devel-
oping against great odds.

Results with Melanconiumn sacchari
A second series of experiments was carried out in a similar way with the
rind disease fungus, M. sacchari, which was always associated with the foot
rot of a seedling cane. The fungus was isolated from blocks of diseased
tissue, increased in pure cultures in cane juice agar, and blocks of the ac-
tively growing fungus were placed over the young cane buds at the time of
planting. Only one soil type was used in the experiment, results of which
are summarized in table 2.
Here again the results indicate that this fungus is not able to infect
healthy, vigorously growing Crystallina cane. Figure 5 shows some of the
plants in this series.

FIG. 5. 1. Plants inoculated with Melanconium sacehari. 2. Check in sterilized soil.


TABLE 2.-The effect of inoculating Crystallina cane with Melanconium sacchari.
Cane planted March 23, 1925, and harvested January 7, 1926

Type of soil and Inoculations No. of Results
treatment plants
No sign of root or stalk rot
L Sterilized Inoculated 24 in any of the plants
L Sterilized Uninoculated 4 do
L Unsterilized Inoculated 6 do
L Unsterilized Uninoculated 6 do

Inoculation Experiments with Various OrganisMS
In this series of experiments the bases of ratoon Crystallina plants dying
from root disease were chopped into small pieces and the material used to
inoculate the seed pieces. The buds were covered with a quantity of the
chopped material, which was held in place by moist filter paper. The soils
were taken from diseased areas where considerable complaint of losses from
root disease had been made. Soils I and IV were used in this series and
were treated as in the previous experiments. The results are summarized
in table 3.
Here, again, when diseased tissue was used for inoculations so that any
parasitic fungus present might have opportunity to act, no signs of the root
disease developed (Fig. 6). The plants were removed from the small cans,

TABLE 3.-The effect of inoculat"'ng Crystallina cane with chopped diseased cane roots
and stalk bases. Cane planted March 23, 1925, and harvested January 8, 1926

Type of soil and Inoculations No. of Results
treatment plants
I. Sterilized . Inoculated 18 No sign of infection
I. do . Uninoculated 4 do
IV do Inoculated 8 do
IV. do Uninoculated 3 do
IV. Unsterilized Inoculated 6 do

the soil washed away from the bases of the stalks, and a careful inspection
made of both the roots and the stalks. The latter were split down to the
seed piece. The soil was washed from the roots of typical plants from some
of these experiments. The root systems of these plants are sbown in fig-
ures 7 and 8.

Discussion of Results
Since the type of root disease under experimentation in these three series
of cultures is that characteristic of a very large percentage of the troubles of


this nature all over the Island, and since the preliminary experiments failed
to show any primary invading organism, we must analyze the problem some-
what further to see if we can arrive at the key to the situation. It is evident
that we are dealing with a variety of cane-growing conditions, but in the end
the invading organisms, with some exceptions, are the same. These organ-
isms we find to be semi-parasitic in that they invaded only weakened tissues
and thus were not capable of infecting the healthy plants in the experiments.
Therefore it becomes evident that in all of these soils we have some factors
operating to injure or weaken the plants. Field studies in various parts of
the Island have indicated some of these causes contributing to the dying out
of the cane, the more important of which are discussed later. The term root
rot, which has been so commonly applied to this dying out of cane, covers a
very large number of primary causes for the weakening of the plants, which
are then invaded by fungi which could not otherwise attack them. In reali-
zation of this fact, which has been established by experimentation and field
observation, the first thing to be investigated when plants in the field begin
dying out is whether the trouble may not be accounted for by one of the
reasons discussed below. We do have some cases which cannot be thus ac-
counted for. These are under investigation, but the experiments have not
progressed far enough to be reported upon except to describe the occurrence
of the disease, its effect upon the plants, etc.


FIG. 6. 1. Plants inoculated with material obtained from chopped diseased cane roots
and stalks. 2. Check, uninoculated.


Under non-pathogenic factors will be grouped a number of conditions,
essentially ecological, which are of direct concern in determining the phys-
ical and chemical fitness of the soil environment to the health and develop-
ment of the roots of the cane plants. While any of the factors mentioned
below may be individually active and are discussed more or less individually,
it is seen that in a given case in nature a number of them may be simul-
taneously involved in the development of a given condition in the soil which,
for several reasons, may be extremely deleterious to plant growth. Further-
more, as will also be discussed, some of these factors may be active in a more
or less alternate fashion and in this way insure a more continuous injury to
the health of the plants. This might well be instanced in cases where the
soil is especially subject to conditions of flood and drought. Thus an in-
tricate complex series of factors frequently must be taken into account, as
well as the individual conditions referred to, in considering the health and
development of the cane plant in any particular case. The enumeration and
discussion of the more outstanding of these conditions which so frequently
constitute the primary cause of the so-called root disease in cane represents
the purpose of this part of the report.
Lack of Drainage
In point of area concerned, lack of or deficient drainage is one of the most
important reasons why cane can not be grown to any extent in the Island.

Fid. 7. Root systems of plants artificially inoculated. 1. Soil III, inoculated with
Melanconium Iau. 2. Soil II, inoculated with Melanconium sacchari. 3. Inoculated
with chopped diseased cane roots and stalks. 4. Uninoculated cheek.


This condition is particularly prominent in the regions of the heavy brown
and black impervious soils of the coastal plains and river flats throughout
the country, especially in the Province of Oriente.
In our observations, extensive areas are encountered very commonly
where the question of economic production upon the soil involved has abso-
lutely no basis for discussion or consideration until an efficient system of
drainage is supplied.
In picturing a plant struggling along in such an environment it must be
remembered that every living cell in its tissues is entirely dependent upon
the life-sustaining process of respiration. This is dependent, in turn, upon
ready accessibility to air. Imagine the anaemic nature of the process in one
of these suffering plants with its roots buried in sticky, soggy clay, where
at times the whole of the soil surface is flooded with free water through
periods perhaps of several days or weeks. Plants dying under these condi-
tions of strangulation have been frequently referred to as victims of root rot.
It has been found that the drainage problem is further complicated over
rather extensive areas, particularly in Oriente and upon the Coastal Plains
in the other provinces, through the presence of common salt in toxic concen-
tration. In certain areas adjacent to or recently influenced by the sea in
this and other provinces, the impregnation of these heavy clays with salt is
so great that it frequently appears as surface incrustations upon the banks of

FIb. 8. Root systems of plants artificially inoculated. 1 and 2. Soil IV inoculated
and uninoculated with chopped diseased cane roots and stalks. 3. Soil II inoculated with
Melanconium ilian.


shallow ditches or on the bottoms of evaporating pools. Samples of the soils
have been analyzed from these general regions which show a total salinity as
high as 0.3, 0.4, and even 0.5 per cent. The concentration is usually found
to increase with depth. In terms of total salts the incrustations referred to
as being left by snall evaporating pools contain as much as 5 per cent as
sampled. Salt flats in positions adjacent to the sea and bearing character-
istic vegetation in the form of shrubs, grasses, and weeds quite commonly
have a salt concentration in the top soil of 2 per cent. While this is imani-
festly not a cane soil, we have seen cane planted in such positions in actual
competition with mangrove and salt willow.
As indicating the rather general condition in this connection, the con-
centrations given in table 4 were found at the depths indicated in a fairly
heavy coastal clay in the south of Havana Province. Here the surface soil
was a dark brown clay, passing at two inches into a lighter brown plastic
clay, and at 5 inches into yellow plastic clay. This became heavier and
more impervious with depth, and a faint gray mottling appeared at about
44 inches. These samples were taken early in 1925 and the analyses made
by the Bureau of Soils in Washington.
The present discussion is concerned primarily with such concentrations
of salts as will visibly affect the health of the plant through toxicity to grow-
TABLE 4.-The concentration of salt at certain depths in a heavy coastal clay soil in
southern Havana Province, Cuba

Sample no. Soil depth in inches Salt in per cent
32659 0- 2 0.21
32661 5- 8 0.41
32662 8-44 0.67
32664 56-65 1.04

ing roots. Injury from such a source of course predisposes these organs to
natural rotting. Active toxicity of this type has been observed in several
areas. In the case of the cane plant, however, it is highly important to
understand that the tonnage of the crop removed from saline soils gives no
assurance of a normal rendement of sugar in the mill. For, while the salt
may be present in sub-toxic concentration in the soil and the plants develop
in an apparently normal manner, its accumulation in their juices may still
be such as to hinder the crystallization of sugar in the mill, and a high pro-
duction of molasses will result.
Similarly, waters from the ditches or wells of some of these regions are
heavily charged with salt and frequently brackish. Waters from open
ditches have shown as high as 11,000 parts per million in terms of total
salts. While on these areas the absolute drainage conditions may vary
somewhat, either locally or in general, from those discussed above where the


salt factor is absent, the solution for their development is absolutely the
same, namely, drainage. For unless ditches are opened for the natural
washing out of these readily soluble salts, the situation may be expected to
become increasingly serious with continued cultivation. Under such con-
ditions, the plants, with the natural handicap of the presence in solution of
a toxic substance, usually make less growth or perish more quickly than
where deficient drainage alone is a factor.
Besides the direct effects of these drainage conditions upon the plant,
their damage is reflected indirectly through the effect of the changed physical
structure and aerability of the soil mass upon the development and activity
of the soil microflora. This, as noted, is produced through the lack of aera-
tion brought about by the general degeneration of the physical condition of
the soil structure as well as the presence in certain areas of the toxic salts
indicated. The depression, or loss in this manner, of the activity of the
various important groups of the soil flora in their effective preparation of
certain of the soil constituents for assimilation by plants must also be re-
garded as a serious matter.

Lack of Moisture
In contrast to the conditions discussed under lack of drainage, moisture
deficiencies are usually most commonly associated with the pervious red
soils so far as the soil types of importance in cane production are concerned.
To be sure, serious difficulties of this nature are also experienced in the
lighter sabana soils when they are cultivated. This is due largely to the
fact of their extreme permeability and comparatively small capacity for re-
tention of available moisture. The moisture situation in this respect is com-
plicated by the alternation, in seasons of approximately six months each, of
rainfall and drought. Thus the cane upon soils that are weak in their ability
to store water may naturally be expected to suffer greatly during this exten-
sive period of rainfall deficiency. Furthermore, certain types of red soil
appear to dry out much more than others. Thus in February of last year,
1925, in certain areas of a red soil in Camagiiey, no apparent moisture was
encountered even at a depth of 40 inches. The soil was so dry that it could
be brought to the surface, even from this depth, only with great difficulty,
since it powdered under the soil auger and fell back into the hole as the
instrument was withdrawn. This has since been found to be the usual con-
dition of this soil during the dry season.
Upon a soil of this type the moisture deficiency referred to is regarded
as of first importance, and the protection of the plant in this respect, par-
ticularly by methods of planting and subsequent cultivation and fertiliza-
tion, is a most important consideration.
Moisture deficiencies also appear during the dry season upon the heavy
brown and black soils, referred to previously as usually suffering from lack


cC drainage. Here the results are frequently very serious; in contrast to
the general deportment of the red soils, the brown and black soils usually
crack very badly. This, in addition to producing serious physical damage
to the roots of the plants, exposes a much greater surface of the soil, and
particularly the deeper layers, to evaporation. The desirability of prevent-
ing this tendency both for the protection of the roots of the plants from
physical injury and desiccation and the conservation of moisture in the soil
is readily apparent and will be discussed further.
In either case the weakness imposed upon the roots of the plants by such
a long period of desiccation is a very serious handicap to their immediate
and future development. The mutilation of these organs in the fashion in-
dicated also leads to an undue exposure of these parts to the natural micro-
flora of the soil, which is ever seeking ready sources of energy of the type
represented in abundance by the carbohydrates in these structures. Conse-
quently, if the conditions are too rigorous, the roots are certain to decay.
There are extensive areas in the western part of the Island where this
condition is to be very commonly observed, either in patches or in whole
fields. Here the stand of cane exhibits varying degrees of degeneration.
It is a noteworthy fact, and one that has been demonstrated in several in-
stances, that where these areas have been cultivated and planted according
to practices in keeping with rational agriculture, the trouble disappears
entirely and good yields result. It is a fact truly worth keeping in mind
that the manipulation of the available supply of moisture is a most impor-
tant consideration in the cultivation of cane in Cuba. However, where
plants have been overcome by this general condition, and their entire root
system practically destroyed by the drying out and cracking of the soil, the
trouble is frequently referred to as root rot.

Deficient Cultivation
The term cultivation is here used to include practices in the preparation
of the seed bed, the planting of the seed, and the treatment of the soil sub-
sequent to the appearance of the young plants, whether plant cane or ratoon,
previous to the closing of the middles.
It is obvious that cultivation in this sense is very intimately related to
the conditions of drainage and moisture discussed above. In the case of
heavy impervious soils the chief significance lies in the matter of plowing
in banks and level planting, while in the instance of the pervious red soils
it is deep plowing and deep planting. Observations have been made upon
plantings under good conditions of cultivation in both cases, however, which
indicate the desirability of some very fundamental studies in root range,
particularly in relation to varietal adaptability before too specific recommen-
dations can be made in this connection.


Fic. 9. Roots of cane, showing the effect of planting and cultivation on root devel-
opment. The white line indicates the original position of the soil level. The figures on
the tape indicate decimeters.

Whether upon porous red soil or the other extremity, the impervious
brown and black clays, proper cultivation or other practices productive of
the same results subsequent to the appearance of the young plants is an
absolute necessity in the control of grass and weeds. Herein is one of the
great dangers of deficient drainage, for the excess of moisture which pro-
motes the growth of obnoxious weeds in the cane fields simultaneously pre-
vents the application of such cultural practices as will not only destroy this
growth but assist very materially in the maintenance of a proper physical
condition of the soil.
In the majority of cases this can best be done by moving the trash to
alternate middles, or, where the trash is light, from two middles into a third,
and cultivating those exposed. By such a procedure a sufficient trash cov-
ering is put upon one row to keep down the weeds, while in those exposed
they are destroyed by cultivation. In the case of the heavy, stiff, black
clays, this procedure serves not only to destroy the weeds but to reduce the
drying out and cracking of the surface and sub-surface soils and conse-
quently effectively to prevent the physical injury to the roots which these
conditions produce. It was largely through the development of such a pro-


gram of cultivation that the successful restoration of the declining produc-
tion on the red soils of western Cuba was first locally demonstrated.
Figure 9 shows the difference to be expected between poorly planted and
cultivated canes and those receiving the treatment described. The stool on
the left represents primavera (spring) cane at one year of age. This was
planted in April, 1924. The cane piece shown in cross section in the cen-
tral part of the root mass represents the original seed piece. Two months
before the picture was taken, when the cane was less than 10 months old, a
test cutting showed a yield of 97,000 arrobas of net cane per caballeria (37
short tons per acre). The roots on the right represent one of the best stools
in the first ratoon of an improperly planted and improperly cared for field.
Here at the first cut from primavera the yield was slightly less than 25,000
arrobas per caballeria (9.5 tons per acre). At the time of taking the pic-
ture the stand in the latter case was showing all the conventional signs of
root rot, being very irregular and having many patches and areas from
which the cane had practically disappeared. Taken as a whole the crop
was scarcely worth cutting. At the time of harvest the weight of net cane
in the former stool was 8412 lbs., while that of the inferior stool was 5 lbs.
In matters of cultivation, the manner of cutting the cane at the time of
harvest and the method of applying fertilizers are of considerable impor-
tance in relation to the control of the depth of root development. This is
made apparent by the illustrations in figure 10. The stools were taken from
a burned-over area on an average red soil in Camagney Province, and show
the extreme superficiality of the root systems that may develop after a suc-
cession of annual cuttings. These stools were removed after the eighth cut-
ting from cane that had not been cultivated since planting in virgin soil
after burning the original forest growth. The tendency is especially well
shown in B, where the buds that germinated were exceedingly superficial
and the general condition and position of the root system in relation to the
surface of the soil (indicated by the white line) is very bad.
Attention is called to the shallow dead stems on the left in figure 10, A,
with the rootstock passing from beneath these to the right. It is seen that
the maximum depth of this part is slightly more than 4 inches. There were
a total of four plants in this stool. Two other stems sprang from the upper
part of the rootstock, but were cut away to show the connections more
clearly. The shallowness of the prospective root system is apparent. The
general condition in B is particularly bad in this respect. Note that the
stalks on the left (two smaller ones cut away from front) spring from top
of old stem to right, also the larger stems to the right. This old stem is
seen to be rotting down the center to within an inch of the dead rhizome of
the year past. Parts of the lower section of the young plants were also be-
coming discolored at the time of examination. It is a point of importance
in connection with the plants here discussed that in the general area of red


soil from which they were taken, infestation by root mealybug is particularly
common and frequently bad. In the immediate area from which these stools
were taken an examination of the roots of more than 50 stools showed an
infestation of 100 per cent.
The tendency for the stool to rise, as referred to above, may also be
accentuated by fertilizing methods. In the application of the fertilizer ma-
terials it is recognized as the better procedure in the case of ratoon cane to
make a desaporque (furrow turned from along rows toward middle) along
both rows in the exposed middle and spread the fertilizer along the exposed
bases of the cane stools. After this application the soil should be worked
back into the furrow by subsequent cultivation. The importance of the
offbarring in cutting away the old root structures and aerating the soil mass
about the living centers of the cane stool is readily apparent and has long
since been established in Cuban agriculture.
The application of the fertilizer in the bottom of such furrows rather
than on the top of the stool is to be no less emphasized. By so doing the
material is placed in a position to be immediately available to the newly

FIG. 10. Photographs A and B showing the superficial nature of roots of ratoon plants
taken, after eighth cutting, from burned over area on red soil, Aug. 19, 1925.

78 P11YToPATHOLooY [VOL. 17

.1A11 A L r

FIG. 11. Cane growing upon good red soil in Matanzas Province on opposite sides
of same guardarraya, although on different colonias. A. No fertilization, no cultivation;
B. fertilized and cultivated.


formed roots of the plant. By virtue of its position, the tendency also will
be for their development downward rather than upward, as might be ex-
pected where it is placed superficially above their normal zone of growth.
The general degeneration in the stand and yield of cane as the result
of deficient cultivation is well shown in figure 11, A and B. These two
fields are located upon opposite sides of the same guardarraya, and the soil,
identical in both cases, is of the good deep red Matanzas clay type derived
from limestone. These fields, though adjacent, are upon different colonias,
and the tremendous difference in the cane stand is due to fertilization and
cultivation. The grass-ridden cane shown in A is not an instance of root
disease or root rot, as frequently has been inferred under similar circum-
stances. It is simply an excellent though unprofitable demonstration of
very poor farming, where this condition develops as a consequence of the
fact that the preparation of the soil, the planting of the seed, the applica-
tion of fertilizer, and consequent cultivation of the cane has been in entire
disregard of the factors here discussed.

Deficient Fertility
It is generally understood that deficiencies in soil fertility in Cuba are
more likely to be encountered in the older agricultural areas of the West.
It is not to be doubted, however, that careful studies in relation to soil type
will indicate specific deficiencies of a more or less local nature to be gen-
erally distributed throughout the Island. Since outstanding deficiencies in
any of the more important elements necessary for plant growth are known
to be the reason for a greatly reduced vigor and resistance, disturbances of
the nature generally discussed above must be expected to appear when the
soil solution to which the plant has access becomes unbalanced in this re-
spect and one or more of the elements becomes unavailable.
The reduction of the vigor of the plants, and consequently the severity
of attack of the fungi and bacteria of the soil upon the weakened roots, will
thus be more or less directly determined by the extent of the deficiency in-
volved. Deficiencies of this nature, particularly in relation to phosphoric
acid and potash, have been studied in connection with both corn and cane
for several years. In fact, it is now definitely thought that the so-called
resistance to these conditions among certain varieties is nothing more nor
less than a lower requirement for the element of which other susceptible
varieties find an inadequate supply in the same environment. This may be
due either to natural differences in feeding power for the same materials or
to actual differences in requirements. The latter appears the more plausible
as between varieties.
While the outstanding elements which the plant must draw from the soil
for the elaboration of its food are nitrogen, phosphorus, and potassium, it
may happen that still others are present in deficient quantities. They may


also be present in such unbalanced proportions as to develop either a toxic
condition or one that is suboptimum to the assimilative interests of the plant
in one way or another. Thus it is possible that in some soil types there may
be a positive calcium deficiency. In others the presence of an excess of
magnesium over calcium may repress the activity or availability of an other-
wise abundant supply of this element even though it be present. This latter
condition seems to be the case most frequently in soils derived from serpen-
tine and is well displayed upon bibijagua (leaf cutting ants) mounds, where
the toxicity, apparently due to the material brought up from the subsoil,
persists even after the mound has almost disappeared as a result of culti-
vation. In certain of these soils the Ca/Mg ratio has been found to be 1: 3
or even wider ; in fact, comparatively high concentrations of magnesium
have been found along with but a trace of calcium. A further considera-
tion will be given this matter in connection with the various types derived
from this material as well as with other types when more analyses are avail-
able. On the other hand, where the soil is deficient in calcium and the ma-
terial brought up by these insects is calcareous, the benefits to plant growth
are at once apparent in the better growth and color of the cane upon these
spots. This contrast of effects is commonly to be observed in one way or
another upon soils of this type. In the case of those having the injurious
type of subsoil referred to, the natural outcrop of this material is frequently
the cause of local to fairly extensive sabana areas.
Manifestly the only logical solution of this general phase of the problem
is a systematic study of varietal requirements in relation to soil type. At
the present time, however, upon areas where the cane is doubtless suffering
from specific deficiencies of this nature, in complex with one or more of the
conditions discussed above, the impaired stand and dying cane is sometimes
attributed to root rot.

Other Factors
In a substratum possessing such native complexity as the soil, there is a
great variety of factors that might appear to disturb the metabolism of living
plants which are directly dependent upon it for a vital part of the raw ma-
terials from which their food and consequently their whole structure is
The availability of the more common elements has been emphasized. The
importance of their balance should also be noted. In this, lime should be
included, for it is important not only in the maintenance of a desirable reac-
tion and physical condition of the soil but calcium is among the more impor-
tant elements necessary in the metabolism of plants.
Soil acidity is also an important consideration in many cane producing
countries, but in Cuba the soils used for cane are, for the most part, slightly
or actively alkaline. Elsewhere under conditions of excessive acidity, it has


been recognized for several years that the release of such toxic substances as
aluminum, manganese, or iron has a deleterious effect upon plant growth;
and, in relation to cane production in Hawaii and corn production in certain
parts of the United States, this problem is receiving considerable study.
In the matter of definite soil type peculiarities that require attention in
connection with general plant response, those associated with what has been
tentatively classed as Oriente clay should be considered. In this the topsoil
is a heavy black clay high in organic matter and usually low in lime. It
cracks badly on drying and is underlain at 5 to 16 inches with a white chalky
line sometimes mixed with argillaceous material or in combination with
hard or semi-hard limestone. It is a matter of connon observation in many
parts of the Island that this chalky material when brought into the zone of
root development is very deleterious to plant growth. In fact, when the
growing roots come in contact with this stratum they are said to turn quite
upward and away from it. The appreciation of this effect is so general that
in some instances deep plowing is assigned as the cause of crop failure in
areas where this chalk could not possibly be reached with the plow. In such
cases the degeneration of the cane was doubtless due rather to an impaired
physical condition of the soil as a consequence of its improper handling. As
noted above, cane is also commonly observed to do badly on many of the soils
derived from serpentine. In some it will scarcely grow at all. Information
at hand at the present time on the specific nature of the active principle in-
volved in such instances is only sufficient for conjecture. Systematic studies
in the laboratory and in the field upon this, as upon other broader relations,
should yield information of the greatest importance, for analogous peculiari-
ties in the interrelation of plant to soil type are to be found in other in-
In the matter of simple physical injury to the living roots of the cane as
a predisposing circumstance or condition to the entrance of the normal sapro-
phytic fungi and bacteria of the soil into these structures, the situation is
seriously complicated by certain soil-inhabiting insects that infest and feed
upon these underground parts of the plants. Those that have been most
commonly observed in this connection under field conditions in Cuba are the
root mealybug, the white grub, termites, certain root borers, and, in very
limited areas, wireworms. Any of these, through their natural feeding
habits, open the plant to secondary parasites that commonly do much more
serious damage than the original wounds inflicted by the insects themselves.
In studying a definite situation involving failing or dying cane which has
the appearance of root rot, therefore, care should be taken early in the ex-
amination to ascertain whether attacks of this nature may not represent the
primary source of injury, due consideration of course being given to the
possible cyclic or seasonal nature of their appearance in each instance.
Furthermore, important correlations are found to exist between soil type
and the facility with which the infestation by sone of these insects proceeds.


In general the relation is one of pulverulence or natural mulching (polvillo)
upon drying. This point will be touched upon in some detail in a later
paper. In this connection it is of interest to note the important part which
snails are reported to be playing in this same r6le upon the roots of the cane
in Louisiana.3 No significant infestations of this type have been observed
by the writers in Cuba.
In regard to the irregular condition of the cane that is frequently found
along the margins of the fields adjacent to the guardarrayas (firelanes) and
particularly at the corners, it has been observed that this condition of the
external growth is considered altogether too frequently as an indication that
the entire field is suffering from root rot. It is found, however, that the
more common cause for this condition is the promiscuous turning into the
fields of the heavy cane carts, particularly during rainy weather; the forag-
ing of animals, either while at work or at large and also the simultaneous
or subsequent encroachment of grass and weeds from the guardarraya.
Where such parts of the field have been passed over repeatedly by carts and
the soil thoroughly packed and in poor physical condition generally, con-
siderable difficulty is frequently experienced in re-establishing the stand of
cane. As noted above, this irregular condition of cane brought about either
through physical injury from carts or bulls or through competition of weeds,
or both, has been frequently referred to as root rot.

The terms "root disease'' or "root rot'' have been applied to the dying
of sugar cane under a variety of conditions, which are grouped as patho-
genic, due to fungi and other parasitic organisms, and as non-pathogenic,
due to lack of drainage, lack of moisture, deficiencies in fertility, cultivation,
and other factors.
Of the various fungi isolated from diseased cane stools, two species of
Melanconium were suspected of having a causal relation to the injury, but
inoculations of cane plants in pots of sterilized soil with pure cultures and
with decaying rootstocks gave negative results.
The field studies showed root disease to be associated with lack of aeration
.in undrained soils, with high salt content of the soil, with drought and re-
sultant cracking of the soil, with high cutting and surface application of fer-
tilizers, with infertile soils, and with the attacks on the roots of several
insects and other small animals.
Improved agricultural practices are indicated as the most important
means of relief.
3 RANDs, R. D. Root disease of sugar cano in Louisiana. U. S. Dept. Agr. Cire.
366. 1926.

[Reprinted from PHYTOPATrIIOLOGY, Febru;ary, 1927, Vol. XVII, No. 2]



During the process of investigations to determine the primary causes
for dying out of sugar cane plants (Saccharum officinarum) in the sugar
estates in Cuba, a foot or basal stalk rot has been found which does not
seem to have been previously recorded or described. This disease was first
observed by the writer in parts of Oriente province in November, 1924,
in spring planted cane of about eight months growth. During 1925 the
disease was again found in the western part of Camaguey province upon
stubble cane of tbe third ratoon. In each case the disease was quite

. t s at
anVheNmr fs

FI. 1. Stool of sugar cane affected with zoiate foot rot. Note the size of the Stool
and the number of shoots, many of which are dead.
Scientific Contributions No. 5, Tropical Plant Research Fotundation, from the
Cuba Sugar Club Experiment Station, Central Baragul, Cuba.


widely distributed over considerable areas within the immediate localities.
In the pathological collections of the Cuban Experiment Station at
Santiago de las Vegas, a portion of a stalk of cane infected with this
disease is reported2 as having been sent to the station by a mill manager
in Oriente province September 28, 1923. The present known distribution
of the disease is therefore confined to widely separated localities in the
provinces of Camagney and Oriente, Cuba.

In both cases where this disease has been observed in the field, the
dying plants were surrounded by very strong, vigorously growing cane.
In the first instance a few hills along the edges of the fields were observed
to be wilting, and a close examination of these stools revealed a large
number of dead shoots (Fig. 1). After the trash had been cleared away
it was found that every stalk in the stool was diseased, and that some of

FIG. 2. Portion of a hill of cane affected with zonate foot rot.
2 Personal letter from Stephen C. Bruner, Pathologist, Estacion Experimental
Agronomica, to the author.


the larger stalks seemed to be dying rather suddenly. Such infected
plants may occur singly or in spots of several hills. In one case an area
was observed where six hills were dead. In another case two healthy
plants were found entirely surrounded by plants dying of this zonate rot.
In the primavera or spring cane the diseased plants were inconspicuous
at first, as they were about the same height as the healthy cane. When-
ever the foot rot had progressed far enough in a considerable number of
stalks to stop the water supply, the hills presented the noticeably uneven,
ragged appearance shown in figure 1.
Figure 2 is a photograph of a portion of a stool of cane which was
killed by the zonate foot rot disease. This hill of cane produced 19 cane
stalks which reached a good size before succumbing to the disease. Note
the size of the stalks, many of which were 112 to 2 inches in diameter. No
cane suitable for milling was harvested from this stool. The pithy hollow
character noticeable at the tops of the stalks is often found in plants
affected with this disease. This I attribute to the continued drain upon
the moisture of the stalk after the root system has ceased functioning.
Thus the stalk is dried out and becomes pithy and hollow between the nodes
preceding decay from secondary fungi or bacteria. In some cases there is
a central cylinder of brownish tissue whose color seems to be developed
through chemical changes and degeneration of the cell walls of the center
of the stalk. Surface sterilized plugs have been taken from this brown
tissue above the area showing the zonated dry rot and plated in cane juice
agar, but no organisms have developed.

FIG. 3. Surface view of a portion of a cane stalk affected with zonate fcot rot. This
shows the clear surface markings.


FTG. 4. Longitudinal section of the base of a cane stalk showing the characteristic
zonate foot rot. At A is a root in which the cortex has been decayed.

The disease has been found in considerable quantities upon two very
different types of soil, one the Saltanejo or "hog wallow'' soil of Oriente
province, and the other a dark chocolate red soil of the Matanzas clay
type. The former of these is very heavy black soil with a clay subsoil, and
the latter is a porous red soil. Since these types are very different in
their physical characteristics, soil solution, etc., there is little indication
that the disease is limited to any great extent by soil type.

At the bases of invaded stalks we find a zonate dry rot which leaves
distinct rings of a blackish brown color upon the rind at that point.
These ring-like zones are usually concave in form and more conspicuous
above each node in the base of the diseased stalk. They are often obscure


until the wax coat of the stalk is removed, when they are very striking
in appearance. Such zones are characteristic of no other known cane
disease and serve as an easy method of separating this from other similar
cane troubles.
Upon cutting either a cross or a longitudinal section of the stem it will
be seen that these conspicuous zones on the rind are but the continuation
of characteristic zones in the pith of the stem. Figure 3 shows these zones
on the outer part of ihe rind. They tend to be concentric, but wider apart
at the top the farther they are from the node.
A longitudinal section of the base of the stalk shows well defined
alternating regions of gray and reddish tissues. The reddish bands are
usually narrower than the gray, but both zones vary considerably in
width. These zonated areas are below ground or within the first few
inches above the soil surface. The cane cutters cut such stalks above the
dry, woody portion; hence canes from the diseased areas might not in-
dicate the presence of the infection. Figure 4 is a photograph of a
longitudinal section through the base of a cane stalk with the characteristic
zoning of the tissues. The alternating gray and reddish layers are more
striking in appearance in fresh material than in the photographs. They
are also more conspicuous in infected stalks which are still alive than in
older dried stalks, as in the latter case the reddish zones may have almost
faded out. In such cases the color usually remains in the more fibrous parts
of the stem. The marks most persistent on the dead canes are the zones
formed on the rind of the stalk.
The ring bordering upon the healthy tissues of the stem is a deep
blood red in color. This is separated from the ring below by a somewhat
wider grayish zone, and this in turn is followed by a brownish red zone.
These zones fade to a brown or buff color when the tissues are completely
dead. Above the last root ring shown in figure 4 the stalk was sound
and showed no signs of rotting. However, the plant was wilting from the
lack of moisture. It had a sufficiently well developed root system and
plenty of rain had fallen to supply moisture, but the roots could not
function because of the obstruction to the upward passage of the water
by this dry rot.
Figure 5 shows the base of a stalk with an excellently developed root
system, the lower part of which had lost its power to function because
the woody zonated tissue prevented free communication with the stalk.
This plant has tried to overcome the decreased supply of water by push-
ing out roots from the higher nodes. The disease has progressed to the
node indicated by the arrow. Above this point the tissues of the stalk
have every appearance of normal tissue. This sharp differentiation be-
tween the diseased and the healthy tissues by the advancing zone is char-
acteristic of the rot.


FIG. 5. Longitudinal section of a sugar cane stalk affected with zoite foot rot. The
arrow indicates the most advanced zone of infection.

A cross section of infected stalks shows the zonated condition to a very
marked degree. Here the zones roughly approach concentric circles in
form. The zone bordering the healthy tissue is a deep red color, and
there is a marked tendency of the color to fade as the tissue rots. The
infected tissue is dry and woody and thus in marked contrast to the fresh
sappy pith of the portion of the stem not yet affected. Figure 6 is a photo-
graph of sections of four infected stalks.

The chief point of entrance of the fungus into the cane seems to be
the base of the stalk. Some cases have been observed which suggested the
possibility that the disease might begin at an infected root, but in every
case the zones could be connected with others proceeding from the base
of the stalk. Figure 4, A shows concentric rings formed around a root


FIG. 6. Photograph of the cross section of four stalks of sugar cane infected with
zonate foot rot. A shows a part of the stalk infected and a part uninfected. Note the
sharp dividing line between the diseased and healthy pith.

entrance into the stalk. The cortex of the root was decayed but the central
cylinder appeared to be little affected.
The disease has been traced in its course from the main primary stalk
through the point of attachment into the secondary buds, from these
through the point of attachment into the tertiary buds and into the shoots
of the fourth rank. In every case the destruction was complete: the
entire copa or stool was dead. The zonate markings stay intact and con-
tinue through the woody underground parts of the stalks as well as
through the internodes. Figure 8 is a diagrammatic longitudinal section
showing the relation of the successive branches of the underground stems
and the path of spread of the disease.


The infection starts from the infected ratoon or stubble cane as shown
in figure 8, 1, and proceeds in turn into stalks number 2, 3, and 4. In
many cases observed, the disease had spread to every shoot, both young
and old, and the entire stools eventually died. In other instances a stool
was found partially infected, but every indication pointed to complete
destruction of the hill in time.

In the root rot of sugar cane we have an infection confined to the
roots of the plants in the early stages of the disease. Even plants badly
stunted and with very short, stubby roots of one or two centimeters in
length often show no signs of stalk rot, though the leaves may be wilting
from lack of moisture. In the zonate foot rot the roots of the plant grow
vigorously until the upward conduction of the sap is prevented by the dry



FIG. 7. Photograph of young shoots showing progress of zonate rot from older to
younger tillers.

rot of the stalk base. In some cases the cortex of a root appears to be
infected (Fig. 4, A), but in such cases it has not been determined whether
the disease appeared first in the stalk and spread to the root or in the root
first. From figure 4 it would seem that the disease had spread from the
stalk to the root.
Both root rot and zonate foot rot usually appear in localized spots
in the fields, but while root rot is largely confined to areas in which there
is some conspicuous cultural defect, such as lack of drainage, etc., the
zonate rot appears in vigorously growing cane under good cultural condi-


In Cuba, as well as in other cane-growing countries, a root and basal
stalk rot occurs which follows injury to cane weakened by other agencies,
as, for example, high concentrations of injurious salts, soil deficiencies,
drought, water-logged soils, and attacks of white grubs, root mealybugs,
and wireworms. This is the type most in evidence in the Cuban cane
fields. The final rotting is done largely by Melanconium sacchari, in some
cases M. ilian, and some other fungi which have not fruited as yet in
cultures. This is the type of trouble generally referred to locally as root
disease. A number of experiments have been carried out with the above
mentioned fungi, and with finely chopped diseased roots and stalk bases
to determine whether these agencies are primarily responsible for the
incidence of the disease. Experiments were carried out in both sterilized

FIG. 8. Diagrammatic cross section of a portion of a stool of sugar cane showing the
progress of the zonate foot rot. The disease enters the primary shoot (1) from the old
infected stubble and progresses through shoots of 2nd, 3rd and 4th rank.

and unsterilized soil taken from diseased areas. No primary infection
was secured. It is quite evident that previous weakening is necessary
before cane plants succumb to this type of disease. The organisms seem
to be semi-parasitic and play a secondary role in the injury of the plant.
In such diseased plants there are cylinders of infected bundle fibers
extending through several internodes of the stalks. The plants attacked
are stunted in their growth, have no marked zones at the base, but begin
wilting and drying long before they finally die. The rot is not dry or
woody, as it is in the case of the zonate rot.
Upon seeing cane affected with this zonate rot, Dr. G. Wilbrink, of
Java, remarked to the writer that a similar disease is called Stengelbrand,


or stalk burning, in that country. This Javan disease is usually confined
to sporadic cases in the young cane, but may become epidemic in a field.
In affected plants the young spots on the stalks are a watery red color.
The cells in these areas are all dead, the parenchyma dying first and
later the sclerenehyina of the vascular strands. A marked difference in
the Stengelbrand of Java and the zonate foot rot is the absence of zonated
markings in the former. Also there are brown leaf spots associated with
the Javan disease by which the affected plants may always be identified.
No such spots have been observed in connection with the zonated rot.

While making a periodic inspection in some fields in which there was
zonate foot rot in the cane, plants were found with brackets of a Fomes

FIG. 9. Cane stalk affected with zonate foot rot, with the bracket of a species of
Fomes attached.


species at the base. Longitudinal sections of these stalks showed the
characteristic zoning at the ground surface and the fungous strands
throughout the diseased portions of the stalks. The brackets were firmly
attached to the stalks and so intimately associated with the zonated areas
as strongly to suggest that this fungus was the probable causative or-
ganism. Figure 9 is a photograph of a portion of an affected stalk upon
which has developed a bracket of this Fomcs.
Specimens of such canes were submitted to Dr. J. R. Weir for identi-
fication, but the fungus was sterile. Dr. Weir states "the fungus is a
species of Fornes with structure peculiar to a group typically represented
by F. pachyphloeus Pat. and F. melanodermus Pat."
Figure 10 shows the brown fungous strands (A) throughout the stalk
and the intimate association of the Pomes with the zonated portion of the
cane stalk (B).
Many canes have been found which show only dhe zonate foot rot but
no ease has been found of a cane attacked by the Fomes which did not
also show the zonated condition.

FiG. 10. Longitudinal section of two cane stalks affected with zonate foot rot upon
which the Fomes species has developed. A. Brown strands of the Fornes throughout the
cane stalk. B. Fomes intimately associated with the zonated parts of the stalk.

J4 P I I 1ol'ATIoJo( y [VOL. 17

It seems quite possible that species of Fomes attacks sonic tree species
in the forests, but neither its exact identification nor its host relationships
have been determined. As pointed out before, the zonate foot rot of
cane has been found only in fields where the cane had been planted in
-monte'' land, that is, immediately after the cutting of the forests.

1. A description is given of a zonate foot rot of sugar cane which
occurs in two widely separated localities in Cuba.
2. There is no indication that the disease is limited to certain types
of soil, for it has been found on a very heavy black soil with a clay subsoil
and on a porous red soil.
3. The disease is characterized by a zonate dry rot at the base of the
stalk. Alternating bands of gray and reddish tissue are conspicuous
above each node.
4. Fruiting bodies of a species of Fomes are often associated with the
zonate rot. The species has not been identified, nor its host relationships


SB215.T8 1927 no, 4
Faris, James Abraham, 1890-1933
Sugar cane root disease in Cuba / w/ no. 5

SB215 .T8 1927 no. 5
Faris, James Abraham, 1890-1933
Zonate foot rot of sugar cane / w/ no. 4