THE STKAWBEKRY M1LD]^:W. 
137 
and the conidia were then sown in a hanging drop of water at ordinary 
temperature. In some cases conidia were placed direct on blocks of ice 
for twelve hours before being sown. Control experiments were made at 
the same time with conidia taken fresh from Strawberry plants in the 
open. In all cases the conidia subjected to this low temperature were 
found to possess greater powers of germination than those sown straight 
from the plant. The favourable eftect of the treatment was shown not 
only in the slightly higher percentage of conidia that germinated, but 
especially in their more vigorous subsequent growth. This is seen at 
fig. 35, h and c, drawn from conidia germinating in a hanging drop. 
At fig. 35, a, three conidia, sown direct from the plant, are shown 
germinating after seventeen hours in water ; at fig. 35, h, three conidia, 
sown after being cooled, are seen to have produced much longer hyphaB. 
The greatest development that was observed among untreated conidia is 
shown at fig. 35, d, where two conidia are represented after being sown 
for five days ; at c is shown the much more vigorous growth that the 
cooled conidia exhibited after being sown for four days in a hanging 
drop. 
It would appear, therefore, that in nature a decrease of temperature 
may cause plants to be attacked by mildew, not only because the vitality 
of the plants may perhaps be weakened, and so rendered less able to with- 
stand the attacks of parasites, but also by directly increasing the germi - 
nating powers of the spores of the parasitic fungus. 
Fimgicides. — Experiments were made with two fungicides: (1) a pre- 
paration made as follows : One ounce of carbonate of copper is mixed 
with five ounces of carbonate of ammonia and dissolved in a quart of hot 
water ; when dissolved sixteen gallons of water are added. This is the 
mixture recommended by Humphrey (4). (2) the well-known fungicide 
against Oidium, made by dissolving a quarter of an ounce of sulphide of 
potassium in a gallon of water. 
The plants treated with these two fungicides were selected as being 
the worst affected, and stood side by side with untreated plants during the 
experiment. After a few good sprayings the treated plants showed signs 
of considerable improvement. The plants sprayed with No. 1 mixture 
were noticeably healthier and more vigorous than any of those in the un- 
treated rows. Not only was the mycelium on the older leaves killed, but 
these leaves, previously badly affected and more or less curled, had so far 
recovered as to uncurl and resume their normal appearance ; also on the 
young leaves no trace of the fungus, after a careful search, could be found. 
On the plants treated with No. 2 mixture the fungus had nearly dis- 
appeared, although on the young leaves isolated patches of Oidium still 
existed. On the older leaves, however, the fungus had been killed, and 
the leaves had nearly resumed their normal appearance. 
It seems probable, therefore, that spraying with either of these fungi- 
cides — preferably with No. 1 mixture — would be successful in combating 
the disease ; but it must carefully be borne in mind that preventive 
measures must be taken while the fungus is in its early stage on the 
leaves, for once in full vigour on the fruit nothing can be done to save 
the crop. As the mycelium is wholly superficial it is possible that 
spraying with hot water (as hot as the Strawberry leaves will bear) might 
