Pear Rust. 
26 1 
He states that this injury is most frequent in orchards which 
have received nitrogenous manures ; and this is confirmed by 
the reports received by him from farmers. 
Accepting Dr. Sorauer’s interpretation, which fits in to the 
conditions under which the injury appeared this year in 
Worcestershire, when we had an unusually dry summer, it 
is most desirable that, when the apples are formed, and the 
moisture in the soil has been consumed during a period of dry 
weather, there should be given to the trees a supply of water. 
If this were done by way of experiment in orchards where the 
apples presented this year the appearance described, and well 
shown in the reproduced photograph, by watering some trees 
and leaving others unwatered, important progress would be 
made towards the successful treatment of this malady. 
A serious disease of the pear trees in an orchard in Sussex 
was investigated. It had been found on all the pear trees. 
The leaves were covered with numerous bright orange-red 
patches the size of a threepenny piece, or larger. The parasitic 
fungus producing this injury is called Gymnosporangium 
Sabince Dicks., or commonly pear rust. The fungus was first 
noticed in June. Under the microscope these patches are 
found to have numerous small raised pustules of a slightly 
darker colour than the patch, each of which has a small 
opening at its apex. The cells of the pustule are thick walled. 
When ripe, it is found to be filled with small irregularly shaped 
colourless spores. In September these appear on the under 
surface of the leaf immediately below the patches ; on the 
upper surface are larger pustules of a reddish colour with 
an orange coloured apex. This is another phase of the life 
of the fungus, and is called the aecidium stage. These pustules 
contain numerous aecidiospores, which escape into the air 
when ripe. This corresponds to the aecidium stage of the 
wheat rust fangus which is found on the barberry, and both 
of these must find another host plant for their further develop- 
ment. The spores of the barberry attack the wheat, and those 
of the pear grow on Juniperus Sabina. They attack the 
young and tender shoots of the juniper, and form oblong 
swellings which in the spring throw out golden yellow oblong 
masses, consisting of spores embedded in mucilage. These 
find their way to the pear tree and penetrate the young leaf, 
forming, in time, the orange-red patches. As this history of 
the fungus is well known, measures for prevention can be 
suggested. Careful search must be made to get rid of every 
plant of Sabine’s juniper in or near the orchard. If the host 
plant which produces the spores in spring that germinate on 
the pear leaves were destroyed, the further attacks would be 
prevented. Spraying with a weak Bordeaux mixture (say 
