18 
Bulletin 69. 
An extended discussion of this subject will be found in Bulletin 
No. 70 of this Station. 
FORMULAS FOR TREATING DISEASED SEED POTATOES. 
Corrosive sublimate.1 ounce 
Water.8 gallons 
Dissolve the corrosive sublimate in one gallon of hot water, 
then dilute with seven gallons of cold water. Allow the potatoes to 
soak one and one-half hours. When dry they may be cut and 
planted, though it has been found to be a good practice to treat the 
potatoes a week or more before planting, since the treatment may 
retard germination if done just before planting. 
Corrosive sublimate is a deadly poison, and it should be used 
in wooden or earthen vessels, since it corrodes metals. 
Formalin..8 ounces 
Water... .15 gallons 
Soak the potatoes two hours in this solution, preferably a short 
time before planting. This remedy is somewhat more expensive 
than the corrosive sublimate treatment, but it has the advantage of 
being non-poisonous, and it may be used in any kind of vessels. 
QUINCE RUST. 
i 
( Gymnosporangium . Sp.) 
Last season the quinces in some sections of the Western slope 
were quite generally attacked by a fungus that is commonly known 
as rust. The fruits were often much distorted and worthless, as 
shown in the illustration in Plate VIII., Fig. 1. Any part of the 
fruits may be attacked, but in this case the blossom end was elong¬ 
ated into a hard knotty mass, on the surface of which was many 
fine tube-like projections about a quarter of an inch long, in which 
spores were produced. Fruits which were attacked when quite 
young were much dwarfed and so distorted that they scarcely re¬ 
sembled quince fruits. The fungus may also attack the stems and 
leaves of quince trees, but on the few trees that were hastily ex¬ 
amined, it was only found upon the fruit. 
The peculiar and interesting life history of this plant disease 
was worked out a number of years ago, which is briefly as follows: 
The fungus has two stages in its development, which are produced 
on two distinct classes of plants. The first stage occurs on cedar 
and juniper trees, on which it produces enlargments of the twigs 
and branches. The fungus lives year after year within the tissues, 
and the injuries are gradually extended until the branch or even 
the tree may be killed. Spores are given off in the spring of the 
year from conspicuous orange-colored masses which grow out from 
