New YorK AGRICULTURAL EXPERIMENT STATION. 144 
In general, it is more destructive in old plantations than in 
new ones, and as the age of a plantation increases the virulence 
of the disease increases. However, there are exceptions to this 
rule. At Marlboro, N. Y., a plantation ef Couwtant No. 1 was so 
severely attacked in 1900 that the crop was reduced fully one 
third. In 1901 and 1902 the loss from cane blight in this plan- 
tation was inconsiderable. At Charlotte, N. Y., in a planta- 
tion of Cuthbert, the loss, as estimated by the owner, was two- 
thirds of the crop in 1901 and only one-fourth in 1902. No doubt 
the virulence of the disease varies considerably from season to 
season owing to variation in weather conditions. Like most 
fungi, the fungus causing cane blight probably thrives best and 
spreads fastest in wet seasons, and yet losses from the disease 
may be heaviest in dry seasons. This comes about from the 
fact that canes become infected during the first season of their 
growth, but do not show the effects until the following season. 
It seems likely that the spread of the disease is most influenced 
by weather conditions during the period of infection and that 
after infection has once taken place the growth of the fungus 
within the cane is not materially affected by any weather condi- 
tion except temperature. Furthermore, the effect of the disease 
is to restrict the circulation of sap in the canes. The death of the 
cane at the point of attack hinders the passage of water to the 
parts above and the leaves wilt from lack of it. It stands to 
reason that when the soil is full of water the leaves on affected 
canes would be able to hold out longer than in times of drought, 
when even unaffected plants have difficulty in getting water 
enough to maintain life. Since the requirements of the raspberry 
plant for water are greatest when the fruit is ripening, that is the 
time when the strangling effect of the disease may be expected 
to do the most damage. 
Reasoning from what has just been said, it seems probable that 
cane blight will be most destructive when a warm, wet summer 
and autumn, suitable to infection, are followed by a warm spring 
and drought in July when the fruit is ripening; and, vice versa, 
the disease will be least destructive when a dry, cool summer 
and autumn are followed by a cool spring and wet July. Ifa 
part of the infection occurs in spring —a point not definitely 
