Fungus diseases of coffee in Porto Rico

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Title:
Fungus diseases of coffee in Porto Rico
Series Title:
Bulletin / Porto Rico Agricultural Experiment Station ;
Physical Description:
29 p., vii p. of plates : ill. ; 24 cm.
Language:
English
Creator:
Fawcett, G. L ( George Lorenzo ), 1878-
Publisher:
Porto Rico Agricultural Experiment Station
Place of Publication:
Mayagüez, P.R
Publication Date:

Subjects

Subjects / Keywords:
Coffee -- Diseases and pests -- Puerto Rico   ( lcsh )
Fungal diseases of plants -- Puerto Rico   ( lcsh )
Genre:
government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )

Notes

Statement of Responsibility:
by G.L. Fawcett.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 020024147
oclc - 21269671
Classification:
lcc - SB608.C6 F38 1915
ddc - 630.7 P82b, no.17
System ID:
AA00014643:00001


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Im










: Issued Febrary 9, 1915.

?.rPORTO RICO AGRICULTURAL EXPERIMENT STATION,
.r .... .
SD. W. MAY, Special Agent in Charge,
Mayaguez, P. R.


Bulletin No. 17.


IITU. .U



:: UNGUS





'"i
. .....


J



DISEASES OF COFFEE IN


PORTO RICO.


BY


G. L. FAWCETT,

Plant Pathologist.










UNDER THE SUPERVISION OF
OFFICE OF EXPERIMENT STATIONS,
V. S. DEPARTMENT OF AGRICULTURE.


. ... .. .
.ii.
R"'






: :i:" "i


WASHINGTON:
GOVERNMENT PRINTING OFFICE.
1915.


ii. .





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e. .. as




Mam
me .j




PORTOROAr
[Udrt uevsin fA RE Drcmo h MI f1fpruu
Unitd StfimDe~t~mt f Arlmlure

















G.- L. FAWCE.---.....-ft.----
CLF.xwA,,Ho~umitU














LETTER OF TRANSMITTAL.


PORT Rco AGRICULTURAL EXPERIMENT STATION,
SMayaguez, P. R., October 15, 1914.
Sia: I transmit herewith a manuscript on Fungus Diseases of
SCoffee in Porto Rico.
The seriousness of these troubles from the standpoint of one of the
leading industries of Porto Rico justify the studies herein set forth,
: and the methods suggested for combating the diseases, which are
now causing enormous losses, should be widely disseminated among
the planters of the island.
I respectfully recommend that this manuscript be issued as Bul-
letin No. 17 of this station and that it be published in both English
and Spanish.
Respectfully, D. W. MAY,
Special Agent in Charge.
S Dr; A. C. TRuE,
Director Office of Experiment Stations,
U. S. Department of Agriculture, Washington, D. C.

Recommended for publication.
A. C. TRUE, Director.

Publication authorized.
D. F. HousTON,
Secretary of Agriculture.
(8)




I




" ": : ..






























CONTENTS.


Page.
Introduction......----------......-----------------.................................................------- 7
S Leaf rot or thread blight (Pellicularia koleroga).......... I ................- 8
Leaf spot (Stilbella flavida).................................................. 11
Root diseases--..---..----.....................................................------------------------------------------.. 15
N ~--- ----------------------------------2
Berry spot (Cercospora cofeicola)........................................... 21
Studies of the spot fungus........................................ ... 26
Miscellaneous diseases..--.--------.....-----....................---------------------.............--------27
Summary--------------..............------------................---------....................------......------.....---.. 29
(5)
















iEd







L.
























ILLUSTRATIONS.


PLATE I. Coffee branch attacked by thread blight (Pellicuvlari 7bkolra), show-
ing characteristic suspension of leaves by threads of the fungus
II. Coffee leaves attacked by the leaL spot fungus (Stilbella fla~vida) ----
III. Mig. I.-Coffee tree attacked by the root disease fun~gum (Rosellnia op.)
Fig. 2.-Imperfect form of root disease fungus (Dematophora sp.) on
Petiveria pla* ... 6................... .... 1 ...... .............
IV. Coffee leaves attacked by the zonal leaf -spot (Cephalosporiu op-)
showing upper and lower surfaces ................................
V. Trunk of coffee tree with Fusarium disease produced by inoculation..
_VI. Root of coffee tree. Roughened bark deto' nemiitodea, 4oot
killed by white root fungus ...........................
VII. A-. --Spot on leaf showing fruiting bodies of Stilbella flavida. B.-En-,
larged head of fruiting body of Stilbella flavidz. C and D.-Threads
of Pellicularia koleroga, showing branching, .....................
VIII. A.-Asu and spore of Toelii 0P.- T.-H hL and' spores of












S FUNGUS DISEASES OF COFFEE IN PORTO RICO.

INTRODUCTION.
Fungus diseases of coffee are common in Porto Rico, and in
S many instances destructive. The reduction in the yield and con-
sequent loss which result from their activity are not definitely
known, but they must be large. The small crop of many plan-
tations is no doubt due to the constant though often inconspicuous
defoliation and killing of the trees which they cause. It is desired
not only to attract attention to these diseases, but to suggest such
means of getting rid of them as have been shown by experience to be
of value. The excellent but costly methods of fighting disease, such
as those practiced in the case of the intensively cultivated citrus
fruits, are not to be recommended so unhesitatingly for coffee, the
profits from which are not so great as to make the cost of production
of small importance. Moreover, coffee is often grown in extended
plantings in mountainous country where it receives so little cultiva-
tion as to be hardly more than a wild plant. Where these conditions
exist it is not likely that any more attention will be given the diseases
than in the past. But there are other, usually smaller, plantations
where it would seem worth while to take advantage of any measures
of value in keeping up their present good condition, either by fight-
i ng those diseases that have already become established or keeping
them from the healthy young plantings.
It is expected also that a publication of this nature will be of value
in.dispelling the idea entertained by some planters that the diseases
of this plant have been so neglected as to be practically unknown, but
only await scientific study to be entirely done away with. Some of
the coffee diseases of Porto Rico are common to other coffee-growing
countries, and were first described many years ago. Suggestions as
to their control have been made from time to time by laboratory
workers, but apparently the methods have never been tried by grow-
ers, else such value as these suggestions possess would have been pre-
viously realized. The knowledge of the life history of the parasitic
organisms causing the diseases has led to no entirely successful
method for their control, if this is taken to mean some way in which
the diseases may be very easily eradicated without some expense and
careful attention in application.
(7)






an I-aC06i,
Wiguua nictd4
....... .. ............. b e n som
Infm Adm dil i |roe ~
Venezuei~~i= laweeii~nw s" weio -h
ha beirprtdfrmthtiiityisaso-M W
OR!!!!]] exmiaton th ma fte ugsWkv
wil efon o helwe id f h tis !!*a
iiiiiii i t brnhst-Ati-e l vw gpY
On.he..wl.a.ackd.la.....s.wb.... .,
brw.Telae n hc h
hodadwih ae-~dbl&otnbv
pmme n o h -ro tewba
P totela.A ute Wi
__ _| -" eie nt ac
celn h oe ie ftela.M n
Mem orkie O k .pee fg i
CMCFm otefeLgfr o ugs
=aeil u h e-ys h he&t h
iiie
........... n x m mo hc ln teA sadbace
grwhi ece rs nwihofe
whch ar tNm ht eoebon fe ie ra
IL&,)bt. fenrmin nmld
Whc uil snwsure fi foW e,
"1cn h es lcs r-wnt emd o
brnhdtras hc eie hfjga oaatsxa'I
toda od.Imeilhi wlaatog h
.pataetela on fe t1jta daepoa ly









17PrR.A+
S wull. 17. Port'. R .r., A.--" E>.p1 S-tai:.r
C-


PL-.TE 1.


b .


N\


COFFEE BRANCH ATTACKED BY THREAD BLIGHT 'PELLICULARIA KOLEROGA SHOWING
CHARACTERISTIC SUSPENSION OF LEAVES BY THREADS DF THE FUNGUS.










* p..~


Bul. 17, Porto Rico Agr. Expt. Station.


1 .PLATE II.


:.. ;i






;I





... :,i~iiii

..." d


COFFEE LEAVES ATTACKED BY THE LEAF SPOT FUNGUS (STILBELLA FLAVIDA).









on in the cooler higher elevations wher6 more favorable
0 prevail as to moisture than in the warmer though some-
drier low lands. It spreads from one part of the tree to another
gtLwth, and in the same way to other plants and coffee trees in
with the diseased coffee trees. To other trees, however, some
d c away it is usually communicated by the fungus-infested
dropping or being carried by the wind and adhering to any
leaf or stem on which they happen to fall, the fungus then
out threads which securely glue the leaves to their new host.
uch leaf serves as a center of infection. That the diseased
yes can not adhere so well to dried surfaces is one reason for the
not spreading in dry weather. There is apparently no other
n which this fungus is distributed, and for this reason it would
to be greatly handicapped in comparison with some spore-bear-
Agi. It is, however, so widely distributed and has such a way
ring suddenly in unexpected places that it would seem as
it possessed some other more effective though unapparent
of distribution.
L des coffee, the author has found this fungus on sour orange,
t-ild vines Luffa ogyptica and Cucumis anguria, and the culti-
.|lornamentals Hibiscus and Croton. It is probably able to at-
ilse plants only under very favorable conditions, as they usu-
'.wntain free from the disease even when surrounded by infested
... trees. The fungus also attacks the coffee berries, about one-
g of which are found to have blackened grains, the large propor-
of such grains indicating that some of the injury is due to
iilicularia. In any event the number of berries attacked is so small
lhat as a berry disease it is of little importance. The loss occasioned
b iE-ithis disease is that which results from the destruction of green
S 6le M tissue, and through this the lessened yield of berries. It is prin-
:Iipgally a leaf parasite, but also causes the death of young branches,
which often die after defoliation. When the branch is not killed it
can not again bear leaves until new growth has been made. The
Street must be weakened and the yield correspondingly reduced by
he loss of foliage. What the loss from this source may be it is im-
e to know, but if proportionate to the percentage of leaves
it would equal more than one-fourth in some trees noticed.
H w1=i of leaves is ordinarily much less and frequently many trees
es'i... infection. The loss in yield of berries from this source in most
Splntations is not large. It has never been observed to kill the trees.
I4Ie the mancha de hierro," it is rarely found on poor, half-starved
trs for the reason, no doubt, that such trees usually are in rather
'dy situations and have less foliage.
71478-15----2
Hr i?!i .







teen

Enoth 6fthe filfigue remains o h
plntsothat it is soon as badly diseased asbe
Ap~itys of which both. the boiled, &nd unboiled
effrectiv~e, a's was also the suphar alone applied as'p6w
binitture is really effective.?: The fungits ea_no 11 t6grw
covered, with this spray, and it adheres better than the-he
cides, especially when made up Ywith twice the usual Winoona of
Ow'n to the frequent and heavy rains of the wetsao
spray is washed off to some extent after a few days. I
to 'increase the adhesion various substances were added t6, thq-
ture, including borax, but the ordinary'mixture with enettly aoot
amount of lime Was found to'be better than any, of, thto&
use of any spray. material difficulties -are met with, samdrio M
that otriigtepotodirect the spray".Oo as to cover
sides of the leaves and to be thorough mi the work, leavn
sprayed, diseased leave osrea centers of infection.,
of the trees reinfection takes place from the pieces of +ugi
whic th spay as issd or which have been partly,
under' the bark- making necessary repeated srynsi h
to be kept clean. It is possible'to destroy' the fungus entire
some trees by one spraying and to prevent the infectioii of
trees to 1a large extent, but to exterminate the disease even wt
peated sprayings is difficult. The work of 'one Year seemed, to
cate that spraying furnished, excellent :means' of .checkingth
ease, but furthertwork ha-s shown it to be less sati f actor than it'
appeared. To open up th-e:trees to. the .Wind and air by, I`ha i
shade could only have'a bad effect 'on the coffee, and is a M
recommended. *
As the nearest approach to a good way of controlling the
Bordeaux mixture made up with 4 pounds: Of copper sulphat-
8 'pounds of unslaked lime or 16 pounds. of sir-slaked ine'7
gallons of water applied as spray to the underside of the'lea6
recommended. 1n no event should a lar ger, area be treated th '
be conveniently looked over from, time to time in order to.n
11In case Bordeaux mixture is to be used in any except very small qpanlti
be well to make up stock solutions of the required ingredients, and take frdm n
time to time as needed. In this way,,it will be always possible to hgye at
up and effective solution, that halving been made up for some time,
ordinary mixture, 4 : 4 : 50 formulas made by dissolving S 00tiddtd
sulphate in.25 gallons of water. The lime and water for-the, other, Ot
made by slaking 8 pounds of live lime, using enough water to. form i
adding to .25 gallons of water. The Bordeaux mixture Is m .ade by tMkliq'
each of the stock solutions, two atsowtendattigtemixture ahe
to often convenient to make the mixtftre In the spray pump.. Tihe form"l TIn ''
wor wiiiii'i th cofedfesfo h bv I igtietead to
th feto aigI deesmwa etrt bflae






11


reappearance of the disease and resprayed when found necessary.
kting the leaves before the spraying will probably be of some
... stance if care is taken to remove as carefully as possible all the
t 1rea ds, on the twigs, using for the purpose the cheaper labor some-
times available for picking the berries.
LEAF SPOT (Stilbella flavida).
This disease does not seem to be known in Porto Rico by any
definite common name, being merely referred to as a spotting of the
leaves. In Venezuela and apparently elsewhere on the continent
and Central America it is called "mancha de hierro," but no doubt
i this term is made to include other small spots of both fungus and
insect origin. It is quite generally distributed throughout the coffee-
growing region of America, having been reported from Mexico, the
Antilles, and Brazil. In Porto Rico it is found principally in the
higher altitudes, where it is favored by excessive rainfall. Lower
down it is found near streams and where it is sheltered from winds
and afforded a moist atmosphere during part of the year. It is more
dependent on moisture than other coffee fungi, being unable to infect
new leaves or to form new fruits except under conditions of extreme
humidity.
The disease is characterized by the occurrence on the leaves of
small spots usually circular in outline, but sometimes ovoid along
the. veins. (P1. II.) The newer ones are very dark, the older ones
light colored. The spots are usually about 6 millimeters in diame-
ter, although many of the older ones become 12 to 13 millimeters in
diameter. Sometimes they fuse or give entrance to other tissue-
destroying fungi which infect the intervening tissue, producing spots
of considerable size. The worst affected leaves have from 30 to 40
or even more spots, so that a large proportion of the leaf tissue is
destroyed. On the upper surface of many of the spots and also to
some extent on the lower surface may be seen hair-like projections
from 1 to 4 millimeters long of a yellowish color, each bearing at the
end a head so that they resemble minute pins. This is the reproduc-
tive or fruiting stage of the fungus. (P1. VII, A and B.) Each
spot produces a continuous crop of these hairs so long as weather
conditions are favorable. The total number at any time is small
and in an entire season but from 20 to 50 are produced in each spot,
judging from the number of old filament bases. The largest number
observed was 70 in a spot of 7 millimeters diameter. As the leaf
spots become older, growth having stopped for aniy reason, such as
the advent of the dry season, the diseased tissue falls away, leaving
numerous circular openings in the leaf. In other leaf diseases the
dead tissue remains.





L m





'Te ncrsope show th laments -while-are.
So~tiesstted, to bmade up of the fin6 fngu
ae smewa branced n the upper par-t to'form the
ensof th:tread& ar 01dlen. and have sometimes
w n in cross section (l1. VI, B)1
Kleassuch. No- raspres have ever, been ound _M Ay o9b`
Amoous spcimens examine.. The fungus is didtribied. b*
has at th ads of th gh nts e caught, by the*W l or
dros and cried, to ear leaves, a process facilitAMd by *4
becoing looened i:the lder filame~nts through the Athah
aiies or unm ze point Of Atc ent. (M
Tehead is on fastndo the leaf on .whidh it happens
tenumeru threads hc it sends: oute:at the pbinf of,
Wtin'ls 1- an a week a rk circular spot in formed anidl_
Sappr and new e attachedheads are formedair a
.mans of whch the srea of the disease is continued. J
ILCL






thsfungou has no oter wy of, propagating itself, 'and thei
hsnot -fun any othr stge of Stilbelld flaida., all, inedeA
inocoffee *h suspeced fom s resulting aegstively. Amftagl
fni weds10 such ino ultos was, one -which answefts so
thdese itns, of kmroti1&be flavida x that it -may, be,
erdidentca with tha fagus. As: 8plusrostizbe, flavid4- is m
tie referd to as the peret stage of Stilbella. flavida, as u M
aspssible ws: made of thsall. amount of material available
fnus wa frst. foun he. j a berry, which, with, others beaO.a
Stlbla. spt, had beensteilized- externally and placed, in, aso
chamer. Alter the sam fungus wa, found o'n, a coffee barry
atahed to te tree, whr sveral of the: Nectria-like fruits 6
veoed in aPot mad by Silbella. These were: studied mr
Di,6t inocultions -o the prithecia into coffee berries did no
Indop cutres of th acspores Cephalosporiumne. dVelo
r cultue from sinl aosqpores this fungus :and late
rimdevelopd. Thi mtrial-was used in inoculttiolk
th.berre0o the treeaid into very thoroughly,'
wsed bries in flas4. A-light infection re Sulted on
beres. O hose in the. flaks perithecia identical de
whc thp ascspores hoo bee taken developed. s
Stell avida resuh-fro the ingculation'se, 3 40Iaed.*,
lave did o take. Thevrk failed -to show AqMA~nti
tefungu ued in th inclations and Stil4ger avida., Of
Mase o.Dt ad [Lw u.Msc nom,10,N.8 p 3-647





13


lasjrnumber of berries affected with Stilbella examined no others with
0i rostilbe were found, so that even if it were a stage of Stilbella
*: Mould play a very small role in the distribution of the disease in
i .. island. If the fungus is a Basidiomycete, as assumed with some
i:"ason by Spegazzini,1 it was not found to possess such a stage.
It is of interest to note that, although the coffee plant is the princi-
pal host of this fungus, numerous other plants are also affected to
some extent. .The writer has found it on such unrelated host plants
as the orange, mango, Begonia, various ferns, several of the coitres
S(Commelina spp.), and guava (Inga vera), and bejuco de carro
% (Velia sicyoides), and have noticed the spots, but not fruits, on the
yautia, banana, and also on several wild plants. The coitres, which
Share perhaps most affected, and the ferns and other plants of low habit
of growth form in, many places a continuous ground covering and
Scratch the greater part of the falling propagative bodies which escape
the coffee leaves, and are hence peculiarly subject to the disease.
They are apparently able to communicate it to unaffected plants of
the same kind and doubtless also to healthy coffee plants. There were
: noticed places where the coffee was not attacked until several weeks
after the ground plants had become infected.
When first taking up the study of coffee diseases in Porto Rico
the "mancha de hierro appeared of small importance, for the reason
that the area affected is so restricted by climatic conditions. But the
regions of the island most affected produce the best coffee, and if it
were not for this disease they would give larger yields. The injury
to the trees is not so much in the actual amount of the leaf tissue
destroyed, although this may amount to one-fifth or even more of the
entire amount in the worst cases, but in the defoliations which take
place after a time. The diseased leaves drop sooner than those not
affected, and owing to the weakened condition of the tree are not soon
replaced. After the first severe attack the base of each tree may be
seen to be surrounded by a pile of green leaves several inches deep.
The disease never kills the trees. They live on with scanty foliage
and are able to put forth some new growth and bear a small amount
of berries each year.
The decrease in yield following an attack of the leaf spot is marked.
In one experimental plat, where a record of the yield had been kept
for some years, it was found to be 75 per cent. In this case the dif-
ference between the trees before and after the attack was such as
accompanies the loss of the greater part of the foliage.
The fungus, Stilbella, also attacks the berries. As mentioned
above, however, it does not do very much harm to the fruit-much
less, in fact than that caused by the Cercospora fruit spot-for it
1Rev. Facult. Agron. y Vet., La Plata, 2 (1896), No. 22, p. 339.







*AA ikh

frhoowgi- cet"M weedso


subjected paration for the maket
Antperimentm'h control- of this-disasewwa
stitiX4La Carmedia, Ittest th4 efliciency of gsffhe4h
itk to diseased leaes a inethod recommnwded in, sawe
o his 'subject. Te trees ='.n oe of the worst dimseaed-
seeced for this, puros and the leaves wihStilbella spots
throws of the surrouding'trees: being similarly treated AO'
to.immediate reinfcion. from. other trees.: The ofect o th
pcing on the pr evlne of the fungus ws roughly
.4ing the relative pportions of diseAse and healthy era
big counted, in th rees of .the pla anch in an equal `ah
Outside. proportion of-diseased berries In Akete
pa in the crop itey f oliowing the, firat Pioke
wa:8 per: cent; ouIi, trn 140 percentt. I, uA4~
teleaves were pice at. intervals of three" months, At;, 4m
teyear- the peree ae of diesdbrisin the treew-1oth.
lase had,.declinedt 16'. per cent,.bti the.. ottsid& treeswt4"
craed to, 32 per, et It -is probable. that an, equaly, largeid,
of'tilbella-affecte brries would -have: been. found, i Wh6 tdreer
whih the disease leves were Ticked, if it !had, not been a!dwd
tretent, thie disae having, made great headway.i all .paidru'
teplantation.--
Further work incmbting. t7 ies asmd mo
cange in, the, management h plantatio'n where the Wlerlo'.
big carried, on. However, such results. as:. h&*e beendti
Woud indicate. tha the disease might be successfly 'combtd
reoing -the diseae leaves. No doubt the defoliation so pro
iasbad for the treas that caused by: t6e fungus, but if the,
wpecarefully don the newly. formed leaves woudldemsaxinr
n ifectinexep as they might be graduUIly rce
ousde the treated aea. The fact that the dieaep
partively slowly -adthat kthe diseased leaves Ire
nizemake this tr atrantmore, easily ferried. out. 41
thtthis slow and:aprently -impracticable methiodlmnig
value in combatn -the diseasd.. where the chmsj~r`
soi of -the- plantatin is available. -snat
Spraying with Bode'auklmixture will exterminszw t446,
weather condition happen: to beftverable, but it ig R
whre the dlisease ismot prevalent hbeasen of the
Th ugscn ifc evsta r o os





15


time; and when the leaves are dry, the time that Bordeaux would
libenst effective by adhering best, the disease is at a standstill, as
iki of the heads which happen to fall on such leaves do not germi-
i t t even if they adhere. The violent downpours soon wash the
Sfungicide from the smooth upper surfaces of the leaves, where it
must adhere to be of any effect. Moreover, the hillsides are so steep
in many places that only knapsack sprayers could be used, and these
only with difficulty. In case spraying is resorted to, it will be of
most value when applied to the healthy trees near the diseased
ones or to those less severely attacked, for the reason that the spray
will prevent the infection of the leaves to which it adheres, though
having no effect in preventing the formation of new propagative
bodies on the already existing spots.
The disease does not spread with great rapidity. In one case
observed it progressed about 200 yards in one year. Many plantings,
probably newer ones, are free from this pest, although climatic con-
ditions are such that it could do much damage if once it obtained
foothold. After it appears in such places it is merely a matter of
time until the entire field is affected, and it is under these condi-
tions, when only a small area is affected, that it can be combated to
most advantage. Unless prevented, it will extend down the mountain
slopes until it reaches drier conditions, the only obstacles to its prog-
ress in other directions being strips of forest or grass land or an
especially exposed or unshaded slope. The coffee of the "altura"
requires less shade than that of the lower lands, but even there it is
seldom that there is an excess of shade. If such exists, it could be
lessened to advantage, for anything making for drier conditions is
unfavorable to this fungus. To cut the shade away entirely, how-
ever, would be a remedy worse than the disease, and one which no
experienced grower would try.
ROOT DISEASES.
In many plantations there are to be found places where all the
coffee trees have died out, the largest of such treeless areas covering
an acre or more. These areas are usually well marked, being sur-
rounded by healthy trees. The death of the trees is due to the action
of certain soil fungi which attack the roots, usually the upper ones,
and the base of the trunk. The first indication that a tree has been
attacked is the drooping and yellowing of the leaves, which later fall,
beginning with those of the lower branches. The roots of the trees
S will be found to be well covered by the thread-like growth of the fungi
and partly decayed. There are two types of the disease, which may
be classified for convenience according to the color of the accompany-
ing fungi as the black (Rosellinia sp.)' and white root diseases. The
1 Apparently RoselUnia bueodes.












arked* the, d' *Img or"& 41
are& Ono CA *ht4 I M-U,
,*irl r", ily beftAiso bf Aia4ftl
dergrowt- h, i 6ot -e
v rod'froiji,
die growth -,An kthis
gs which bo"

6d the 14OW
g 'r, by w,"
Oer: Mteria
7 the eoffeerlre64 so
often doestidba ham.aMang the be the*
61 poor coaeaplauttilojw.,'rema f rleo' fi,
_inovethaj one, 'mstabc6' A has soev*d, t6 sturt wniW'
stuinp or trea, tmmk. As. the fun, gt S"Is knoiin Jivoi
table matter, it, ig probsble thattheft vps, I Urrdsh-
of f-cKd material that it...becomes strong enough tQ'*,tt'x&
*hereas or-dinaffly it: metely m'akes us 0- of theusW
rial coveri. the sm'lin well sh placeg*
31,
the surfaw of: the gro=d becomm t oved.4
'ov 'for,
I;hin brojim CIOMIY -Udh,, watiiig of the
after being attacked.- Oii t6 iopts. and- parts of.' th
the surf ace the MYCOjjUm...1s'Lgatheredmoft into-
eolor which later, becomes -black. Bdow. the tbjm-
tbxeads:fdrm a nearly-solid la r, thi
YIQ 1, CPY grown
this there extends into the bark and wood rooWike b
I -miltimoter Alne cks On. Cutt g. away the, U* itad, W
pear as smaU blitek dota ind lines,, accoiding- tb'ihe
thty am cut. These form OAIe of themoA characteri
the disease-L' In, trees recently hiRed;tha-_Nngui*ilI be
passed but litfle deeper th*n'-thi',xner' baik, although
it may- penetritte 2 or 3 teutiniotbv.' On.,,e ittack ii
$br f R(*6t the gromtIn"Iviuk- tho trunk at the 0,
rOOb;44f_ It" later adv
few inchea,,hut.thie deeper 6o,.uxuftlly
dmally on that: of the- fongus growth nevi ri-,
there are formed
meterslong. Tjiese:,am1'1'ghtl,(frta,,ittthetipi4c,
have a somewhat brush-like appeann(*, At first

















































FIG. 1.-COFFEE TREE ATTACKED BY THE'ROOT DISEASE FUNGUS
(ROSELLINIA SP.).


FIG. 2.-IMPERFECT FORM OF ROOT DISEASE FUNGUS
(DEMATOPHORA SP.) ON PETIVERIA PLANTS.


1 4









r;




























































COFFEE LEAVES ATTACKED BY THE ZONAL LEAF SPOT (CEPHALOSPORFUM SP.), SHOWING UPPER AND LOWE^^^t -
owa r A
Su.. RACES.
.'.. ;:6. : :






'. butMier appepth clusters beneath which are formed
l outgrowths (wolerotia).' The hair-like projections bear
l iores which doubtless serve to distribute the fungus to some
i (] VIII, B.) This: stage of the fungus (Dematophora) is
enimnon, though produced less frequently on coffee than on
ither plants. (PI. 1II, fig. 2.) In the sclerotia are sometimes
other kinds of reproductive bodies that are characteristic of
iosellinia. (P1. VIII, A.) This seems quite rare, as the
-'has found it but twice, once on a wild shrub (Piper sp.) and
ffee.
.ether plants than coffee which this fungus attacks is anamu
liacea), a weed quite common among the coffee. It was
S kill out a thickly growing area of this plant, a grass
i) taking its place. No other plant athong the coffee has
And to be injured except young guamas. Once when the fun-
p...,'aped from pots of infected coffee plants it destroyed the
growing ornamentals, Giaptophyllum pictum, Panax plu-
,; and Acalypha mosaic. It has been noticed once among the
Wad low growths at the edge of a clearing, attacking and killing
1aill the plants with which it came in contact, among which, be-
ihe rose apple, were species of Miconia, Piper, and Palicourea,
4'~ :hrubby habit. A Tradescantia, one of the common ground
:in well-shaded coffee, covered the ground as soon as it was
Sby the fungus. A fern (Adiantum sp.) seemed to be the
plant able to resist its attacks except the large, thick-barked
s and mangoes. The fungus left a vegetation quite different
i that which it found, causing it to appear somewhat like that
Sclearings made for coffee.
l.Ithough acting slowly, the losses to coffee produced by root dis-
ti are probably not exceeded by those from any other cause. The
is greater because the better trees suffer most, especially in
e of the black root disease. The fungus causing this disease
distributedd throughout the coffee-growing regipns of the island,
being limited by climatic factors as are some other diseases. The
~:where the trees have been killed are often left for a long time
Io..e replanting, and after the trees are reestablished it is several
Before they bear fully. -Just how long before the ground be-
fit fbr replanting without treating the soil with some fungicide
not yet been determined, but this probably depends on the amount
-! od material available to the fungus in the soil. In one case
JO$I# the trees replanted where the vegetation had been killed two
4::: f previously have not shown, during a period of eighteen months,
i4y sign of the disease.
Some experiments were made with the hope of finding an effective
yil of controlling the disease. These have included ditching about








the~~~in thes 4rpread- 0tyd 91.',
infeced aeas, a tb tre tmotof the soil wit k
some degree Qx,................on... The.
sdvsabe bwusethe.: ungs.is superfialW, ever'
sol ormoe thnafw:ichlms,. The substane de
in rnaphtholeum, 'and. copper
Th werWe l SMu fairly. easily poured: and qitdte
ifnt too gra vniisshould be necessary lor. their
us.Other susaew m included potassium permangant
P itani~ bisupte. Th efec of breaig 'up the'soil by'ma
hay hoes, a Mehod qiecommon, in cultivating c0000e% -9
tre:in some othe, chc plats and in WlI of the. other
Vosly to thi cultivato all, diseased trees, and semaps
parly decayed vegetal d6bris common 'in" suchplcso
noed. For th ihme expriment' the, soil was frAt b~roken4,
whih the lim was & ttert f 0 gmms per
mer, being t n ino shallow. trenches -and ill
.Tetrenches big. clos tgether, =d- parallel, the
though, no patof th srface being- overlooked.,.. Thegon
prinkled w eketeime adthen ..orked with,
toH"x it. wit te sol WhIenever. a diseased. tree had em,
moed an extr -mount.o lime was added. Similar methob-
-sdin applyin the sulpur, care being taken to mi it th
wihthe soil. Two axe were treated, bone reevn 5_001:mn
sure meter, h other abot one-Nfouth of this amount. -h
rnphtholeum petrlem. distillate product of the sam~e class 46
erolineum, u~ ised n one of the worst diseased places- It" ~
aplied at the rat of abot 50 cubic centimeters per square, Mte
big poured i-5. per cet solution into smaIll holes whith
mae about a fot &art Later the ground was sprayed
bltion and thnwored over with hoes to'secure more
pentration. :s
During the. thre year frce, the -experiment was begun no,
haedied in plas recevig lime and the heavier.,applicatian,
slhur. In techeck plt adjacent to that receivminglime 0--
cetof the tree have de, and about 3. per cefit of the treenirA*
pltwith the .1~e-r-apication of sulphur and in. that rW
techloronaphhlen.= In a: plat of anajm4 showing thisdie
an pplicationo chloronphtholeum awounting to 100 cubic ceet-,
mtrs of the =ilute Peparation and another with the e'
amunt of 450 cbic cenimters per, square meter were made.
haier applicain stope the disease without inj*rin the,
plats. The. dsase wa -nhecked by the lighter
the pants n thi plat, beig kiled b:. th fungo. IU-Any

M't




.:." 19

Treatment with preparations of this nature is not to be considered,
as it is ineffective if the smaller quantities are used and its cost
Si bits the use of large amounts.
SAlthough the use of lime for this disease promised little, still it
lid the advantage of being very cheap and readily procured be-
l sides being often useful in its effects on the physical condition of
the soil. Moreover, if it is even of small.merit in combating the
disease it is to be recommended, as, being already familiar to the
planters, they would use it in preference to other more effective but
Less common materials. The good results obtained from its use in
S these field experiments may be partly due to the disinfecting action
v .of the heat of slaking and possibly, also, to lessening the amount
of vegetable matter in the soil which could be used by the fungus
as food. That the heat generated by slaking may have had some
fungicidal effect is further indicated by the fact that when the
already slaked lime was used in the form of a thin paste at the
rate of 200 grams per square meter on a much-diseased plat of
Petiveria no effect in checking the progress of the fungus was to be
Observed. The use of air-slaked lime is not to be recommended in
the case of the black root disease if it is wished to check the disease
at once by its application. Its effect will be good only as it tends
to improve the soil and hasten somewhat the decomposition of the
vegetable matter on which the fungus feeds. Such action in any
event will be slow.
The good results from the use of sulphur must be referred to its
fungicidal properties. In well-aerated soils sulphur dioxid is prob-
ably formed, and hydrogen sulphid in soils excessively moist. Both
of these substances have weak action as disinfectants. But it is not
unlikely that their continuous production through several months
would serve at least to prevent the growth of the fungus and perhaps
to destroy it. Additional evidence that some such action exists was
obtained by mixing sulphur. in the soil with which a trench about
4 inches deep and of equal width was filled, using about 15 grams
of sulphur to each meter of the trench. The fungus has killed the
plants up to the sulphured soil, but during the entire year on which
it has been observed has not passed to the healthy plants on the other
side. In part of the ditch which received no sulphur the fungus has
passed over and destroyed the Petiveria plants.
In the three years since this work was begun 2 per cent, or 6 out
of 317, trees have died in the treated plats, all of these being in the
plats receiving the smaller applications of sulphur and chloronaph-
tholeum. None have died in those treated with the other disin-
fectants, but the results from the treatment with these substances
are of little interest because of their cost. In the check plats which
- were merely cleaned and ditched 5 per cent, or 16 out of 334, trees
'i1 :EE







hsavo de., -Althetih it is ag yet mlICOn
clusions, it vwoul sum 'that, treatment. of Jh~
stance rendering conditions unfavorable* for Oake
was. of .,practiWa value.
Asto the._cost of. materials sdf, that.of.m
apae etrsis but356fnts Thbcs of sulphur at the
intthe experiment would, be,10 times as:much. However,
be vorth. while to: u-se: even such-remedies if. chape~r material
lesssucessfl. f -begunwhil the: diseased. areas axenoto
68: expense for: such treatment would be: sm~all.
As copper sulphate i sutance which lis injurious~to pln
exception very small'quantity,, it was not thought desirable to p
7o freely to the soil as the: other substances used. Accordingly i4 a
applied only to the trees near those attacked by Roselli'wia. A 44
tity equivalent to 15 grams of the salt was sprayed about the baeoo
the trees. Within a few weeks -the fungus had- passed the sprR
trees,: killing all the Petiveria except near th~e s'offee #rees. The
of the disease that remains in places where the fuxipns'has;
seems to be, less virulent, probably because less, well nour-ishedt
the: copper salt has been washed out- by, rains. the'tree so t~reat4*
probably be subject to attack, from the fungustas-soon as enough- t
material accumulates to give it sufficient start.: The spray ing oXX
entire. surface with a solution of copper sulphate via-& tried, the;
being of such concentration as to equal 25 grams of the salt per,
meter. This was found in an experiment.,on 8 square meters, ol,
badly infested- with the black-root disease- to' be sufficient. tocheh
apparently to exterminate their fungus, wbich has not re1ppeatiQ,.
during the year. which hag passed since the sprayi.g.'The coAt thr
-the copper salt alone used at this rate amounts to 50 cents at 1o*
prices, for a quantity sufficient to treat 400- square meters. -,Wige
the drainage is good, as on the clay hillsides, not enough of the copper
is retained in the soil to be harmful to vegetation... Under such cn
editions and on soil suitably cleaned this is an effective remedy. ,osP
sibly a considerably smaller quantity of the copper salt would B
equally. effective., NHowever, since satisfactory results: can. be seao'
by Other means, the use of copper salts in controlling the diseaaso Ua
not to be recommended.
The work carried on so far would indicate that.-,cleaning th,46,p
ditching, and liming Wre of :vglue in. combating this disease. Tbho
cleaning includes the taking up and removal of the diseased and deA4
coffee trees. .The usual custom of cutting off the tops of such'today
and leaving the stump to decay is-bad. Such, material, together,
pile-up leaves, branches, and other d6bris, hal~fdecayed v
matter which serves the fungusn as od material, should be.am







removed should be ditched about, if they occur in the diseased areas
that are to be treated, as they sometimes seem to harbor the disease.
..he guava and guama, which are frequently killed by borers, leave
Sin y such stumps, and for this reason these trees are undesirable
i as shade trees. If the ground is to be broken up, which is an ad-
vantage if lime is to be added, this should be done immediately after
the cleaning. The ditches should be a foot wide and of somewhat
greater depth. Care should be taken to examine the bases of the
trunks of all the trees to be inclosed by ditches in order to make
sure that no diseased trees have been left inside from which the dis-
ease can be communicated to the others. Such an examination will
usually show some of the healthiest looking trees to be affected with
the disease, often being girdled just below the surface of the soil.
The length of time that such trees can live and bear fruit, after
having been girdled, is indicated by the fact that a coffee tree of
which the bark was removed for a space of 4 inches about the base,
the wound having been painted with carbolineum to kill any living
tissue from which growth might set up, lived for 23 months, bearing
one full and one partial crop. Any tree showing a diseased patch
near the crown should be removed. Ditching about the diseased
areas, together with the gatheIing and destruction of the diseased
trees and vegetable debris, constitutes the most important step in
Controlling the disease. After the earth has been broken up unslaked
lime may be applied, as already described, care being taken not to
place it too close to the trees. If applied in the dry season it should
be sprinkled with water to slake it after mixing with the soil. It
is not likely that a quantity of unslaked lime less than that used in
the experiment (500 grams per square meter) would be effective.
'To summarize, ditching is recommended as preventing the fungus
from passing from diseased to healthy trees; cleaning up vegetable
debris and removal of diseased or dead coffee trees and the addition
of lime or some other substance to the soil are measures of some value
in combating the fungus. The ditches should be cleaned out from
time .to time and vegetable material prevented from accumulating
in the places affected with the disease. Such measures are of special
value where only a few diseased trees are found among otherwise
healthy plantings. Where the centers of infection are too numerous
Sit may be useless to protect with ditches and even less so to use the
other sanitary measures mentioned above except, perhaps, the re-
moval and destruction of diseased trees as soon as observed.
BERRY SPOT (Cercospora coffeicola).
This spot of the berry is troublesome since it causes the fleshy
part of the fruit to adhere to the parchment, thus making the process
of preparation more difficult. It is also the cause, at least indirectly,


L









The fanu'cnn g ohis spot, 66reogpmua
ported from Aentral and South, Americ&*
throughout the -American caffve-gro'wing regiedlf Jia
ifr present to some Jextent in every plantation. Bothlev'
areaffcte bythe disease; On the leaves it cauesre
varying -from, 6 to. 0 millieesi imtr fab
somewhat lighter toward tfe. center thin at the edge*,T
rrely Man onayoelafUn bottle harm is done by, the
as a leaf: arasite as to be negligible.i OA the leaves, howee
produce spores which serve: to spread the disease and to cr
funtgus ever from one 'erop- t6- noer. On -the berries -the l
spts tos fstening -h lsypart of the fruit to the parh
almost always are found 'on the upper side. .Any pxrt of thefo
may be attacked, the spots, appearing' it firt 'as, sbiall, brown d,
colorations. They are, especially common1 on0-the nearly ripe
At, the time of picking, the larger spots cover about haxlf ,obAhe -
and are velvety with the spore-bearinLg- outgoths of the~ft Jb
The occurrence of the largest and, worst spots. on. the, upper. or
exposed side of the berries is to be explained by the fact that the
develop more rapidly in the somewhat ripe tissue that side;
uneven ri Ipening of the berry being caused by the: d01irect eup
each day to the sun rays. After the berries. have, become i
this one-sided ripending takes place more raidly, the berriesC
black above with the Cercosporw spot and -still. green o'n thne
Whether picked. at once or left until thoroughly -ripe the ber
difficult ofprep'aration: and yields -a somewhat inferior
That the riper tissue furnishes. more favorable ..conditions lor.
fungus is indicated by the more, rapid development of -the spots,
cluced by inoculation into ripe beries and: the geter ub
spots- developing on the nearly ripe tissue.:
The uniformity with which the upper Side of the berries it the V9.
most i jured may account for the idea that such berries are ifi
by- hail. -As a matter of fact hail is almost unknown at th's ele44jd
tions where the worst affected, plantations are situated. Alte
better explanation quite commonly given Is that ,the berries'.h
burned by sun either directly or intensified by -the lens-like &cdtist.
drops of water, the' disease itself -beling Air this reason sometimess;
ferred to as the "1 sancocho "of the ber-rie0s.:. The presence of exi or4
ganism, of proved parasitism, even in the earliest stages of the d
eased spots, makes these theories untenable. Sunlight is a f aetotrN"
importane but only as-it influenced, dvlomn f h~pt
happn ton occur on the unner-'ich of the berries. These hatmme




S;"* ^': :23


-unnoticed. There is, however, a small amount of injury to fruits
an4 leaves, not due to parasites, which is to be ascribed to the heat
.,, the sun. On the leaves of unshaded coffee trees such injury is
eHiii: presented by brown shriveled or sunken patches of cells, which in
ii their earliest stages are free from micro-organisms. Occasionally
Such patches of injured cells form the center of yellowish areas. A
similar loss of chlorophyll on the upper side of the berries precedes
Sa premature ripening of the sun-exposed fruit. The berries that
ripen thus without being attacked by Cercospora are few in number.
That the injury in the case of the leaves is sun produced is indi-
Scated by the absence of such "burned tissue in the leaves of shaded
trees_ and the fact that those leaves with more nearly horizontal
or exposed positions are the ones affected. The injury by sunlight
Sis of interest in this connection as it favors infection of the fruits by
Cercospora.
Since the existence of a close relationship between the distribution
of the disease and conditions as to shade would make possible a prac-
tical means of control, it-was thought worth while to secure data
-with regard to this. Accordingly samples were taken from each of
the gatherings made in two fields, one with fairly heavy shade, the
other exposed to the full sunlight. The quantity of berries examined
from each field varied from 132 to 199 liters per season, amounting to
from 15 to 20 per cent of the entire yield. The conditions as to soil
and slope were fairly uniform in each, so that the samples may be
taken as representing the quality of output fairly well. For two
-years determinations were made of the proportion of Cercospora-
spotted berries, including spots of 1 millimeter in length or more.
It was found to vary according to the degree of maturity of the
Samples examined, but reached for the last year 73 per cent for the
shaded and 70 per cent of such berries for the sun exposed. It was
concluded that, so far as the actual distribution of the disease goes, it
is not influenced largely by differences with regard to light. The
relative occurrence of the more troublesome or sancocho" form of
the spots was quite different as, in the determinations made the fol-
lowing year, when there were taken only berries in which the spots
were sufficiently developed to be blackened -and dried to the cascara,
it was found to be 16 per cent in the shaded and 27 in the unshaded
coffee.
It is well known that there is considerable variation in the quality
of coffee, one of the characters of an inferior grade being the larger
proportion of blackened and shriveled grains. As it was thought the
-Cercospora spot of the berry might be the cause of such grains,-at
least indirectly, the spotted berries, used in the work already men-
tioned, were subjected to the usual process of preparing the grain.
In the case of those used in the earlier work, where even slightly










6r,, it*a ou

gn~m
1 41




`l'smis *R .emnd"d tt
* -sn alo dkrm'&.Te
folow

i~doris.
EJ 11t"N
#!ti~vdn htte re '
,OwW rap poqtqFfP
he fngusdoe infpfo~o t
that ,I
i*




themo vwlyw







Bul. 17, Porto Rico Agr. Expt. Station.


prI
I


TRUNK OF COFFEE TREE WITH FUSARIUM DISEASE PRODUCED BY INOCULATION.


PLATE V.










Bul. 17, Porto Rico Agr. Expt. Station.


I.


ROUGHENED BARK DUE TO NEMATODES.
"WHITE" ROOT FUNGUS.


ROOTS KILLED BY


ROOT OF COFFEE TREE.


PLATE VI.










5 -w
C
0 m
-a


rn










'I -I












A.-SPOT ON LEAF SHOWING FRUITING BODIES OF STILBELLA FLAVIDA (X12). B.-ENLARGED HEAD OF FRUITING BODY OF STIL-
BELLA FLAVIDA. C AND D.-THREADS OF PELLICULARIA KOLEROGA, SHOWING BRANCHING (X450).












Bul. 17, Porto Rico Agr. Expt. Station.


PLATE VIII -

































4 ., .
,L












.. "- ..


A.-AscUS AND SPORES OF ROSELLINIA SP. (X450). B.-HYPH/E AND SPORES OF DEMA-
TOPHORA SP. (X450). C.-HYPH/E AND SPORES OF CEPHALOSPORIUM SP. (X450).


4L
i









pailting from increased loss or water trom the spotted rruts, as
a's the admittance through the weakened tissue, at the point
boed, of other organisms which attack the-grain directly. Of
e several have so far been found, the most common being a
~jrhm, identical, apparently, with this stage of the Sphserostilbe,
sdy mentioned. The injury resulting from the spot seems to
a on the age of the fruit attacked. When the infection takes
: aon undeveloped fruits the resulting injury is greater, but if
pain has begun to harden before the spot develops fully it may
injury.
er source of the inferior quality of coffee from sun-exposed
Sto be found in the "granos vanos," berries that seem to be
out and good, but which are easily recognized at the time of
aby their yielding readily to the pressure of the hand and also
ed, blackened pedicels. The name could be applied as well to
.-appearing berries with bad grains mentioned above, but for
ce it is here used to indicate those the injury to which is due
Supply of food material having been cut off, as shown by the
iedicels. Not isolated berries alone, but often all on one branch
entire tree are, affected in this way. The shriveled grain con-
in these berries remains free from fungi or bacteria for a long
,ythe injury being clearly not due to these organisms. The black-
tiisue of the branch at the base of the pedicels always contains a
uum, and occasionally a Fusarium. But _neither of these
was found to be able to attack the tissue of healthy green
s when tried out by inoculations with pure cultures. It would
hat they are only able to attack weakened trees exposed to full
and subject to the unfavorable soil conditions accompanying
tf osure. Not all the trees in unfavorable conditions produced
of this sort. What the proportion may be was not determined,
Sis only large in the first picking. This was omitted in the
*i' work, and in that of the last year the granos vanos" were
irated out, so that the result can not be affected to any extent by
presence in the samples. The hormiguilla (Myrmelachista sp.)
extent the cause of these "empty berries," as it often injures
of the fruit-bearing branches and sometimes the pedicels,
off their supply of food.
Si*n that the soil in well-shaded places is more uniformly
i.in more exposed situations, and no doubt the benefit of
is part due to better soil conditions, especially with
| flb e The soil in unshaded places becomes very dry in
little rains and also very hard where of the clay type.
i.a.blei condition as to moisture is made worse by the pres-

di 4.
EMk m







-ofin grasses -which always coeis
tesin thesepla&ces are slender, .10tha
Aolage. The leaves of thew branches on whiW
t6ese are half grown and: the branches begin to-
Where the blackening extends rapidly, killinOg the
the grnosvans "result The trees, whioh are d
branches for leaves and berries, Are able to, iorn but e
A product of inferior quality' results, owing to the action aOL,
diseases of the fruits and grain, thus 'increasing thie losses
lessened yield.
STUMES OF TESPOT FUNGI.
It is desired to include at this place something of the"tc
of the study. In attempting to determine'definitely the
the organism producing the spots, the earliest stages 01
were studied. The berries with such spots were first
then introduced into the medium, or the spot itself was cut
introduced into the medium, using the usuiiil precautions. VIw-j
sterilization had consisted 'in washing the berries. for three.,
in 90 per cent alcohol, then placing themn in 4 per cent~for
three minutes, and finally washing in sterilized water, the
berries usually gave, in addition to a sterile gryvngus, a
sporium, while the check unspotted berries similarly sterile
gave a Glceosporium~. With less severe sterilization a uri
often obtained in addition to the above.: Later work with
thorough sterilization, gave only the sterile fungus -from thoe.
Both the F-usarium and the Glaeospo Irium were tested in inocul fob
but without positive results. The sterile fungus was used inin
'lations, with ihe results that typical spots were produced -on
Cercospora spores later developed. In. the, checks small ppg
sterile absorbent cotton of about the same size 'M the piece
mycelium were introduced into. small wounids,_the. purps
..roughly to duplicate the conditions of the inoculation. No
resulted in the case of those-checks, although the chances of
infection -from natural sources existed. No attempt. to sterilize
berries on the trees before this inoculation was made, and the
showed .it to be unnecessary. From the. spots resulting froja
inoculation the usual gray sterile fungus was reisolated.
No spores of Cercospora were borne on -the mycelium in
culture. However, on some of the mycelium placed -on the e-,
but slightly introduced into the wound., abundant spores, of
spora were in one instance produced. The material u sed in thoi
lations of the following season was obtained from spores
on typical spots of the berries The spnnegR hecanu of ta




27


germinating spores were transferred directly from the agar of these
,: etures to the usual media. In every case the typical gray sterile
w .m yeelium, similar in every way to that used in the inoculations of
ti7e preceding year, resulted. This when inoculated into the berries
o produced the usual spots from which it was reisolated, and there can
i; thus be no doubt as to the identity of the organism producing this
spot. An attempt was made to show that the spot on the berry could
-be produced by spores from the leaf spots. When transferred di-
rectly from the leaves to the berries no infection resulted. Later
pure cultures from the spores of the Cercospora of the leaf were
obtained, as.in the case of that of the berry. The resulting growth,
whichh was similar in every way to that in cultures of the berry
aungus, when inoculated into the berries, gave positive results, typi-
cal Cercospora spores later developing.
I-: In conclusion it may be said that the spot of the berries produced
*by:' Cercospora coffeicola, which besides interfering with the prepa-
Sation by causing the flesh to dry and adhere to the berry also injures
: ie grain to some extent, may be largely prevented by the use of suffi-
cient shade, as, for example, that of sufficient density to prevent the
A.towth of grasses other than palmilla. Such shade is distinctly
f avorable to the production of coffee free from inferior shrunken
grams.
MISCELLANEOUS DISEASES.
Of less importance but perhaps worth mentioning in any general
i scussion of coffee diseases are the "zoned" leaf spot and a root
|and trunk disease. The leaf spot is characterized by its tendency
i toq develop concentric rings, such rings being sometimes incomplete
...i a the outside of the spot, and often beginning as entirely separate
l spots which increase until united with the central mass (P1. IV).
On the underside of the older spots a thin white mold appears after
a while, which is condensed or massed in places.- This bears the
numerous spores of the fungus (Cephalosporium sp.) (P1. VIII, C.)
which has been shown to be the cause of the spot by isolation from
Sthe beginning spots and by inoculations from pure culture. The
U disease is common among the best coffee, seeming to prefer the young
Sand well-shaded leaves, and all the various species and varieties
cultivated at this station are subject to attack, though it is most
Common on the "Ceylon Hybrid." It has been noticed on other
"::plantations but is nowhere abundant.
Another disease is easily recognized by the smaller diameter of
the affected part of the trunk owing to the bark drying up and
shrinking (Pl. V). After being diseased for a long time the bark
falls away leaving the wood exposed and the calloused outgrowths
at the edge of the healthy bark. If the diseased bark is cut away







iW"
&Avgusl FMerie sp-isa aye prdt's
1,49oWrditions.,with pur cutres have failed 7Of
I is commuiae UY to healthy .trnk
1 ..... ..............., r e a d
Pieces of diseased mateia,' and when'ths .tra~n
itself. to be rapidly develping and, destructive, 14"W
fivng. tissue for: severaL nches above. and below the point,4
lation..
infection appears to take ce rough wounds as, for
the stumps left by cutting of part. of the branches cloge. to tht
It frequently accomEpais -the: white root disease,- attache.
yet living trunk, above th liseased. roots. It seems probable,
can attack the tree ne:ar th crown through small -Woltz&s
those made by the macht in weeding, but no clear
has been found. The chrateristic Fusariumn was' isolatedl
decorticating disease of cofee where all the trees wereates
some 2 or 3 feet from th ground. In this-c-ase -ants and miegy
were also present, so tha the injury wns: probAbly due, inig
place to these insects. Tedecorticated branches, with, th'
outgrowths of healthy tisu at the base of the branches obeas
to be seen are no doubt th after effects of this: fomw of thoe,
disease. 1t
The foregoing 'include a1 the commoner, and more desr
Porto Rican coffee diseae produc-ed by fungi.,Oedsae
caused by Hemileia vastati, which is said to have caused so
damage to the cultivationo this plant in 1Indift and the East, Indi
does not occur here an -hs not been reported from any er
coffee-growing-countr y The threadworm Heterodera: radieicokr",,,
often active in trees suffrig from root disease, Yen founding
cases at thed upper edge, othe diseased area at the base, of. the. tru `V
(PL.VI). It was thouh at. first that, it might be. the real *cause of,,
the white-root disease bu since specimens have been found free from;
this worm there can ben necessary relation bet-weenthe twoe
attacks the base& of the trnk, however, causing, them to, take on*
roughened, somewhat swlln appearance for a foot or::so abov
soil. When: cut into. wit a knife there may, be seen, even wiW e*
naked eye, the minute glblar bodies of the adult females, by, which
such diseased tissue is chraterized. 1 No real evidence: that the trees
are, really injured by ths isease has been nuoticed. The: charat-
istic, swellings caused on rots by this worm may sometimes -be-seev"
on the fine roots near th srfacee. The hea-vy nature of most, PoW,
it sometime s elsehere.






29


SSUMMXARY.

(1) For leaf rot (Pellicularia koleroga) there has been found no
ri.eally satisfactory method of control. The benefit of repeated spray-
ings with Bordeaux mixture is lessened by-the fact that the fungus
is not all killed even by repeated sprayings, enough remaining to
reinfect the trees after a time.
i. (2) For leaf spot (Stilbella flavida) Bordeaux mixture is really
effective, and it may be recommended to prevent the disease from
extending to healthy and productive plantings.
(8) Cercospora spot of the berries, which causes the more badly
affected berries to be pulped with difficulty, and also injures the
Grain to some extent, is to be prevented in its worst form by provid-
Sing sufficient shade, which by rendering less harmful this and other
sources of injury to the grain decidedly improves the quality of the
Output.
(4) The root disease may be prevented from spreading by ditch-
ing, this being preceded by the removal and destruction of vegetable
:6dibris, diseased trees, and stumps. It is apparent that the addition
of unslaked lime, sulphur, and some other substances to the soil
i:prevents the growth of the fungus causing the disease.
(5) Importance is to be placed on the use of preventive measures
Sto keep the still healthy younger plantings in good condition rather
than on attempts to exterminate the diseases among the older trees.







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UNIVERSITY OF FLORIDA


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