New York AGRICULTURAL EXPERIMENT STATION. 345 
open in the spring, followed by the three sprayings that are usu- 
ally given the trees for apple scab. Great pains should be taken 
to see that the limbs are thoroughly protected with the mixture as 
well as the foliage and fruit. The approximate dates of spraying 
may be given as follows: 1. About the time the leaf-buds begin 
to open. 2. About a week before the blossom-buds open. 3. As 
soon as all of the blossoms have fallen. 4. Ten days or two weeks 
after No. 3. 
INVESTIGATIONS IN 1899. 
It was originally planned that this season’s work should be a 
verification of the previous year’s results, namely, the identifica- 
tion of the canker fungus and the determination of its relation to 
what was thought to be the same species that occurs on pear and 
quince trees and on the fruit of all three species of trees. But the 
work broadened as Sphaeropses were found on a variety of hosts 
representing seven orders of plants. 
Since a knowledge of the host plants of any plant disease is of 
great practical value in order that it may be successfully com- 
bated, an attempt was made to determine the relation of the 
species of Sphaeropsis, represented by the different hosts, to the 
canker fungus. | 
In the spring of 1898 specimens of blighted apple-tree twigs 
were received from Odessa, N. Y. It was not determined at the 
time what was the cause of the blight, but a subsequent examina- 
tion revealed the presence of numerous pyenidia containing 
mature spores of a Sphaeropsis. On visiting the orchard late in 
the fall, it was found that the twig blight had been quite notice- 
able in 1897, but there was none to be found on the current sea- 
son’s growth. In all cases noticed, when once attacked, the entire 
growth of the season had been killed and in a few instances the 
disease had extended into the previous season’s growth. There 
were a few miniature canker spots on the smaller limbs but none 
were noticed on the larger branches and the trees were in fairly 
vigorous condition. 
