392 W or maid — ‘ Brown Rot ’ Diseases of Fruit Trees . 
travelling downwards from the other (infected) umbel. To bring about this 
result the fungus must have traversed a distance of from 4-5 to 5-5 cm. 
between the time of inoculation, on May 8, and May 25. 
This experiment proves conclusively that the virulence of the apple 
Blossom Wilt form of Monilia cinerea is not diminished after from one to 
two years’ culture as a saprophyte on artificially prepared media in the 
laboratory. It also shows that the conidia produced on a spur during the 
second year after infection occurs are as virulent as those produced during 
the first year subsequent to infection. 
Experiment 2. 
Strains used J 
B. Apple Blossom Wilt strain, isolated 1918. 
C. A 4 Wither Tip’ strain from a plum tree, isolated 
1918. 
D. From a mummied plum, isolated 1918. 
E. „ „ cherry, „ 
The inoculations were made on May g, 1918. 
It will be seen from the table that during the first six days after 
inoculation the symptoms of infection were generally similar for all the 
four strains ; later the apple . Blossom Wilt strain made rapid progress and 
caused, in the case of two spurs, the death of the whole inflorescence and 
the leaves borne on the spur, while with the other strains the disease was 
confined to the flowers actually inoculated, i. e. the tissues of the spurs were 
not invaded and the leaves were unaffected. 
On May 15 a comparison of the inoculated and the non-inoculated 
flowers showed that in the former infection had occurred in every caso; 
this, together with the fact that of the eighteen flowers inoculated with 
strains C, D, and E all had fallen except two, leads to the conclusion that 
these strains either kill the flowers directly or at least infect the styles and 
so prevent pollination, the final result being the same, viz. the arrest of any 
further development of the flowers, which in consequence wither and fall 
off. The one instance in which the ovary did begin to swell probably 
means that pollination had occurred in that case before the inoculation 
was made. 
