Clxxiv PROCEEDINGS OF THE ROYAL HORTICULTURAL SOCIETY, 
SCIENTIFIC COMMITTEE. 
October 11, 1898. 
Dr. M. T. Masters, F.R.S., in the Chair. 
Present: Dr. H. Muller, Rev. W. Wilks, and Rev. Prof. G. 
Henslow, Hon. Sec. 
Pear Leaves Diseased. —With reference to some leaves sent 
since the last meeting, Prof. William G. Smith, of Leeds, 
reports as follows :— 
“ The Pear leaves with rusty spots are attacked by a Rcestelia, 
one of the group of Uredinece. This fungus is one which com¬ 
pletes its life-history on two host-plants. The leaves submitted 
are those of one host—the Pear. They bear two distinct kinds 
of rusty spots or areas—viz. smooth areas in which the leaf- 
tissue is almost normal, and swollen areas in which the leaf- 
tissue is abnormally increased and full of starch. The smooth 
spots are studded on the upper surface with black points, the 
5 pycnidia ’ or ‘ spermatia ’; as a rule, these were covered with 
a hardened film of what had been sticky masses of ejected 
conidia, generally blackened with smut or bearing saprophytic 
fungi. The swollen pustular areas also bore spermatia on the 
upper surface, and also partially developed aecidium cups em¬ 
bedded in the abnormally increased tissues of the lower half of 
the leaf. The imperfect development of these secidia prevents 
me from identifying the species of Rcestelia exactly: it is pro¬ 
bably It. cancellata. This fungus may also attack the fruit. 
The second host of this ‘ rust ’ is the Savin ( Juniperus Sabina), 
and it would be useful to know if this or an allied Juniperus 
occurs in this garden ; also if they were perfectly healthy. The 
rust is a common source of trouble, especially a form which 
occurs on Apple-trees. This latter is very injurious in the 
United States. American authorities advise removal of the 
second host, the Juniper ; also the destruction of badly diseased 
trees or branches. After these precautions are carried out, 
Bordeaux Mixture is said to give good results. It is used in two 
or three sprayings at intervals of eight to ten days, the first 
given as soon as the young foliage appears. It is also strongly 
urged to. use varieties of Apples or Pears suited to resist the rust. 
