184 
THE TROPICAL 
AGRICULTURIST. 
[Sept. 1, 1898. 
gular blotches which often eventaally cover the greater 
portion of the surface of the leaf. During increase lu 
eize, the spots are often bordered by a narrow dark 
line. The grey or aornetinies white colour of the spots 
is equally evident ou both surfaces of the leaf, and is 
due to the disappearance of tlie chlorophyll, and the 
subsequent death of the cells composing llie tisbue of 
the leaf. The mycelium of the fungus is very deli- 
cate, rarely exceeding 2^ in diameter, hayline, and 
sparingly transversely septate ; it at first occupies 
the intercellular spaces and runs between the cells, 
which eventaally become separated from each other 
by a dense weft of mycelium. Finally the mycelium 
enters the cells and vessels in considerable quantity, 
causing the death of the invaded patches, the uu- 
attacked portion of the leaf remaining quite na- 
changed. When the leaf tissue of the diseased patches 
is quite dead and brittle tne mycelium of the fungus 
becomes aggregated in numerous dense tufts just 
beneath the cuticle, more especially ou the upper 
surface of the leaf. On the lips of these aggrega- 
tions of slender, erect hyphcie, or conidiophores, which 
spring from a basal pseuuoparenchymatous stroma, the 
couidia are borne. As these clusters of couidia increase 
in size they raise the cuticle of the leaf into i series 
of minute warts, until finally the tension is too great, 
and the cuticle ruptures, usually in a triangular slit 
through which the mature couidia protrude and soon 
become free on .he surface of the leaf, from which 
they are removed by wind or rein. Such of those 
aa happen to alight on the moist surface of the leaf 
of a suitable hoot-plaut, germinate at once, enter the 
tissues of the leaf, and form a new centre of disease, 
which in course of time produces couidia. By this 
rapid method of couidia-foruiation and distribution, it 
can bo readily understood how possible and certain it 
is for tlie disease to spread rapidly when once intro- 
duced into a tea garden. 
The conidia are produced at the apex of slender 
hyphae or conidiopnores, and are very beautiful 
objects when seen uuder the microscope, being nar- 
rowly elliptic with somewhat poiuted ends, and usually 
three-septate ; the two eud cells are colourless, 
while the two median cells are olive-brown, the 
tei-minal colourless cell being surmounted by four very 
slender, colourless, spine-like processes longer than 
the coudiuui itself. The above-described is the 
typical and must abundant form of condium; varia- 
tions occur in the number of septa, which range f»om 
two to four ; the hair-like appendages also vary from 
one to four, or are sometimes entirely absent. 
The life-history ot the fungus was ascertained from 
a series of cultures ; living conidia being obtained 
from the fungus growing on " Camellias" cultivated at 
Kew. 
couidia germinated freely within eighteen hoars in 
hanging-drop cultures in ordinary tap water. The 
median dark-coloured cells of the couidia are alone 
capable of germination, each cell as a rule producing 
a single germ-tube ; in rare instances two germ-tubes 
spring from a cell, one of which remains rudimentary. 
On sterilised bread a dense white superficial mycelium 
soon appears, on the surface of which very minute 
dark points, consisting of groups of conidia are 
visible about the third day. Five days after 
sowing, the couidia are mature and capable 
of germination, but bread does not appear to 
be a vtry suitable medium for the cultivation of 
tills fungus, the characteristic terminal, fliloim 
appendages of the conidia being almost constantly 
below the number normally present, and in certain 
tufts entirely absent. The spineless condition of 
conidium agrees exactly with the fungus described 
by Cooke as " Hnudersouia theicola," parasitic on 
living tea leaves from Cachar, which is in reahty 
nothing more than an abnormal form of " Pestal zzia 
Guepini," and has also been observed on " Camellia" 
leaves at Kew. Examples of these abnormal spine- 
less conidia, sown on plum- juice gelatine, gave origin 
to perfectly normal conidia within a week, in fact 
only normal conidia were produced on the last men- 
tioned nutrient solution, whether normal or excep- 
(ioual couidia (in so far aa the number of apical 
spines were concerned) were sown. It is quite an 
easy matter to inoculate living uiiiijjured ''Camellia" 
leaves by placiuK conidia ou the damp under surface of 
the leaf, aud keeping it moist for twu or three days. 
No result was obtained when the conidia were placed 
ou the upper surface of the leaf. 
I'tstaluzzin Guepini ia not known to i)Oi»eesa any 
other form of fruit or mode of repruducliuu thau 
the condition described above. 
The disease under cout'i eration is bj no meani 
new ; specimen of tea leaves attacked by the " Pes- 
talozzia," now in the Kew Ilei barium, are accom- 
panied by the following note. ' Tea leaves (bliKhled). 
Cachar, 187'2 growth, A. H. Blechynden. ' A second 
lot of tea leaves, suffering from the same disease, 
is accompanied by a note as follows. " Lieaves 
from a tea tree recovering froai ' red spider.' Sap 
just beginning to run through them. This tree 
like many thousands has not given any leaf for 
three months. T. li. < uttis. U..ceived from Mr 
Blechynden. Calcutta, by T. B. C., October, 1878." 
The fungus occurs as a parasite ou leaves of 
filants belonging to the following genera : — "Camel- 
ia," "Rhododendron," "Citrus," "Magnolia,' Al- 
pfaitonia,' ' Niphobolus," and " Lagei6tiuemia." 
Owing to its wide distribution at the pr^st-ni day, 
the original home of the fungus is difficult to deter- 
mine with cerlaiuty, but the amount of evid<ince at 
haud suggests an Eastern origin. In India it occuia 
on " Camellia " and " Khododendron " ; in Europe it is 
by no means uncommon, but always on lutrsduced 
plants belonging t J the two above-named genera. In 
the United Slates it occurs on introduced species of 
" Camellia " and "Cilrus," from which itmay possibly 
have passed on to the native " Magnolia." On the 
other hand, it occurs on indigenous plants (Si/iliololue) 
in New Zealand, aud on " Alphltoni't" in (Queensland. 
PKEVENTIVE MEASUKEB.-If thediseased leaves 
were collectea with the amount of care aud intelligence 
exercised in collecting sound leaves, and burned at once 
after being collected, the disease would soon be stamped 
out, as the iiiyceliumof the fungus is not perennial inthe 
tea plant ; consequently infection, and a recurrence of 
the parasite, depends entirely ou inoculation bv the 
numerous conidia or reproductive bodies of the fungus 
present on deceased leaves. Remembering the very 
different kinds of plants on which the fungus is known 
to be parastic, it is very probable that it also occurs on 
wild plants growing in the vicinity of the tea gardens; 
if such proves to be the case, all such plants should 
be removed if practicable, as the conidia of fungi are 
carried considerable distances by wind, birds, and 
insects, and no amount of attention in the way of 
removing the parasite from the tea plants would avail, 
if the supply ol conidia requisite for inoculating the 
tea plants were formed on other plants growing in 
the neighbourhood. 
The name of the fungus, together with the syno- 
nymy, is as follows : — Pestalozzia Guepini, " Desmaz.," 
Ann. Sci. Nat., Ser. 2, XIII., 18'2, tab. 4, figs. 1-3 
(1840). Syn. " Pestalozzia inquinans," Karst., Hedw., 
1891, p. 301. "Pestalozzia Camellie," Passer., Rev. 
Myc, 1887, p. 146. '' Coryneum Camellise," Massee, 
Grev., XX., 8 (1691). "Hendersonia theicola," Cooke 
in Sacc. Syll., IV., No. 2,334 (1864;. 
Fig. 1, Leaf of tea plant showing the pale patches 
formed by " grey blight" (Pestalozzia Guepini) ;nat. 
size. Fig. 2, Section through a pustule of the fruit 
of the fungus ; « 100. Figs. 3 & 4, Conidia of the 
fungus ; f< 400. Fig. 5, Conidia germinating ; x 400. 
BLISTER BLIOHT. 
(" Exobasidium vexaus, " Massee). 
The amount of injury caused by this parasite, along 
with an interesting account of its general appearance 
and mode of life, will be gathered from the follow- 
ing account by Dr. Watt : — " One of the very worst 
blights on tea is known to the planters as " Blister 
Blight. At first it seemed to me as if this might prove 
a species of blister mite (Phytoptus), but I am now 
disposed to regard it as a fungus, and possibly 
a species of " Exoascus " or " Taphrina. In tube No. 
257 I have sent specimens of the disease ia 
