YOL. LVI.— No. 3,138. 
S.VTTRDAY, DKCKMUKR 20. 1913. 
NOTE OF THE WEEK. 
I Silver-leaf Disease. 
j The ravages of the disease commonly 
1 known as Silver-leaf continue to spread 
? with ever-increasing rapidity, and have 
! now become so widespread a.s to annually 
inflict heavy losses upon the owners of fruit 
gardens and plantations, more especially 
m districts where plums are largely growui. 
, This disease has long been known 
I to fniit growers in this country from 
' the silvered appearance of the leaves 
of the trees suffering from an at- 
t tack. Not, however, until within a 
\ quite recent period has its direful 
effects upon plum trees been fully 
recognised by practical cultivators, 
or its cause othei%vise than imper¬ 
fectly understood even by the most 
advanced of plant pathologists. No 
farther back than fourteen or fif¬ 
teen years ago the silvering of the 
leaves of the plum and some other 
fruit trees was believed to he chiefly, 
if not w holly, due to a deficiency of 
iron in the soil, and the remedy al¬ 
most invariably recommended wais 
sulphate of iron, applied in the form 
of a top-dressing, and well watered 
in. Now' it is known to those who 
have devoted some share of their at¬ 
tention to the study of plant dis¬ 
eases that wdien a plum tree has 
leaves of a silvery-grey hue the 
tree is not suffering from an in¬ 
sufficiency of iron or other mineral 
essential to its healthy development, 
hut is the vicitm of an attack by one 
of the most insidious of the fungi 
that prey upon fruit trees. One of 
the scientists to engage in the investigation 
of the Silver-leaf disease was Professor Per- 
cival^ of the Reading University, and as 
the result of his well-directed efforts he 
was able to show, m a communication to 
the Linnean Society’s Journal in 1902, that 
the disease w^as of fungoid origin. He was 
^^so successful in proving to demonstration 
that the fungus causing the disease is Ste- 
reum purpureum, which bears its fruits 
only ob the dead wood of a tree killed by 
the attack. At first Professor Percival’s 
^nclusions w'ere received with some doubt, 
hut this has long since passed away, and 
they are now accepted by all who give at¬ 
tention to the experimental aspects of fi*uit 
culture. Mr. Spencer Pickering, who^ 
Work as Director of the Woburn Experi- 
*iiental Fruit Farm is well known, w'as one 
of the first to put Professor PercivaTs oon- 
. ^tusions to a thorough test, and in the 
ooiiree of his investigations he obtained un¬ 
questionable evidence as to their correct- 
^oss. He, as Professor Peroival had done, 
round that the fungus could be readily 
studied in the various stages of its life his¬ 
tory, and that the disease couhl l>o con- 
veyed from an infi'cRyl tiii*e to one that is 
perfectly healthy without any diffi<*ulty by 
inoculation. The fungus, when it reaches 
the fruiting stage, forms flat diw-s on the 
sill-face of the infectiHl bran<*h, and it was 
simply necessary to take a ]H)rtion of one 
of these, not exceeding double the sijje of 
a pin’s point, and iiiM'rt it in a .small cut 
on one of the branches, to infin-t a healthy 
tree, and cause its untimely death. The 
MR. J. R. TOOLEY. 
facility wdth which disease can he con¬ 
veyed from one tree to another is a point 
of considerable practical importance, mas. 
much as it indicates the necessity of care 
in pruning, and the avoidance, as far a.s 
practicable, of injury to the hark. Careful 
pruning consists in cutting away dead or 
dying blanches well below the indications 
of disease, and in avoiding the use of the 
same knife in pnming diseastnl and healthy 
trees without sterilising, pre\noiis to com¬ 
mencing to prune the latter. The spores 
of the Stereiim are cjirried by the wind 
from one tree to another, and if they can 
effect a lodgment on an abi^sion of the 
bark or a cut, they soon germinate and 
penetrate the tissues, through which they 
spread at a somewhat rapid rate. If, on 
the other hand, they alight on a branch 
with perfectly sound bark, the spores fail 
to germinate, and quickly perish. This 
fact suggests the desirability of not only 
preventing injury to the bark, but of cover¬ 
ing the larger wounds made in pruning the 
with gas-tar, which at Kew is used 
with much success in coating wounds 
cuummI by tlie removal of large branches of 
ornamental for Stereum piirpun'um 
U not th<« only fungm that <i«n <»htain 
actesa to tlie tissue, of trcn * by meam^ of 
cuts ami other w<»un<l.s. .Mr. K. T. Hrouka, 
of tlu‘ ('ambridge I'niversity, biu^ also di^ 
vot4Ml mueh time to the investigation of 
Silverleaf <li>easc. ami in an )m]><»rtant <xm- 
tribution to tlie rurnuit hsue of the 
•* .lourmir' of the Hoard of Agriculture 
be not only <h' rribes the ientific as- 
p4H*t« of the but makes 
Kpt'cial referenda to the imsins by 
w'lii< h it may hebl in cbd'k. Ho 
KUgg<'stH that not only ^dioiihl the 
inf(*cte<l branolu's b<* nmiovdl hut 
that tb<\v sbouhl rut Iwu-k Ixdow 
the limit of the <Ilricoloun'<l wochI. 
of natural re<‘overy of lid's 
W'liit h an* sliglitly <liae4is<Ml are, as 
l)oth .Mr. Hrookf* ami Mr. Spen¬ 
cer l*i<-kering have f<mml in their 
investigations, not infrdpient ; but 
treea that are Iwully silveixx!, ami 
Ix'ginning to di«* bac-k, should, in 
Mr. Hro<»ks.’- opinion, ib^-troydl. 
Such ir<‘e.n ^boubl not oidy be < lit 
<lowii, but they sbouhl lx* n'tnovdl 
from the plantation ami burned. 
To allow <h*ad tre<v to stanil in the 
plantations, or to lx* piUd up on 
their margin.s, is a praclidx by no 
means unknow n ; but it sbouhl lie 
carefully guanldl against, fonvach 
trc'e or pile <>f tn*es Ix'comos a 
centre of inhTtion. Imjimper 
gn'a.sj'-bamling is regar<le<l by Mr. 
Hrooks as another factor which 
favours the development of tb© 
dis 4 >a.se, for where the grease baa 
bien placofl directly on the tr^^e, w 
has soaked tbixnigh the band, the 
liark frequently beoom.*s torn and 
and smh tis8iu*s offer every facility for 
{'^tereiim purpureum to obtain ingress to 
the tree. 
Mr. J. R- Tooley.— A native of 
lioston, in Lincolnshire, Mr. .1. R Tooley 
comes of a seafaring stock, but the ocean 
did not apjieal to him, and at the early 
age of thirteen he was apprentice<l for 
six years with Mr. J. Christie, in the Park 
Nurseries, Boston. After his apprentice¬ 
ship Mr. Tooley decidcxl to enter private 
service, and three years later he was at 
AVaddesdon Manor, learning something 
about orchids under Mr. J. Jacques, but 
it was at Trent Park, New Barnet, under 
Mr. H. H. Lees, that Mr. Tooley acqiiireil 
the taste for exhibiting which has never 
left him. During the seven years he stayed 
at this establishment the names of Trent 
Park and Lees were household words 
among lovers of chrysanthemums, and the 
young foreman was entrusted with the 
staging of many a winning exhibit in 
