THE FLORIST AND POMOLOGIST. 
[February, 
20 
form the whitish-grey downy coating indicative 
of the disease. Thus through the aid of these 
conidia the malady spreads quickly in wet or 
damp but not cold weather, as well as when 
there is abundance of dew, while in dry weather 
it is longer confined to the attacked plants, or 
to their immediate vicinity. It thus becomes 
particularly destructive in vineyards occupying 
damp situations, and is less hurtful when the 
situation or the season are dry. 
Millardet has recently observed the Per- 
onospora not only on the vine leaves, but also 
on the inflorescence and on the fruit bunches, 
sometimes attacking the ramifications, and 
sometimes the berries. The attacked berries 
become first of all doughy, then rotten, 
and finally dried up, as shown in fig. 8, where 
a represents the sound berries, b berries after 
being some few days attacked, c berries after 
being several weeks attacked, and completely 
dried, and d the stalks attacked and dried up. 
Besides the germinating conidia, globular 
spores called oospores, are also formed by 
the fungus threads within the leaf tissue; 
they are found on the globularly swollen end¬ 
cell of a fungus thread, the oosporangium, on 
which the minute end-cell of another fungus 
thread, the antheridium, fastens itself. After 
this globular cell shrinks up, its contents sur¬ 
round themselves with a membrane, and thus 
become converted into an oospore, which is a 
lasting spore, and in opposition to the conidia 
does not germinate till after a long rest. It is 
in this state that the fungus passes the winter 
from year to year in the fallen leaves. This 
Millardet has proved by placing dry vine leaves 
containing oospores of the Peronospora viticola, 
in pots in which grape stones were sown, 
when he found that a great portion of the 
seedlings became infected by the fungus. If, 
therefore, the affected vine leaves which fall 
in autumn are burnt, the cultivator may at least 
often secure the respite of a less severe attack, 
and also the later appearance of the disease. 
This, however, after all, is only a palliation 
of the evil. Many remedies applied to other 
vine diseases have been tried in vain against 
the American Mildew, as for instance the 
sulphuration or washing of the stems with a 
solution of 1 kilog. sulphate of iron in 2 litres 
of water, applied successfully against the 
“ black burner ” (anthracnose). But the ap¬ 
plication of a powder consisting of 4 kilog. of 
pulverised sulphate of iron (green vitriol) 
mixed with 20 kilog. of pulverised sulphate of 
lime, was very successful. In a plantation 
sprinkled with this mixture on the 2nd of July, 
the young shoots did not suffer, but the spots 
of disease blackened and the leaves became 
intensely green. The success of this experi¬ 
ment was the more remarkable as the vines 
were between two sets of diseased vines which 
had not been similarly treated. Another 
plantation vigorously attacked by the mildew, 
was, on the 24th of September, sprinkled in a 
similar manner, and also cured, but in this the 
young shoots and tender leaves were blackened, 
possibly by reason of the abundant rain which 
would quickly dissolve the vitriol, while at the 
July application the weather was hot and dry, 
and the vitriol would be dissolved more 
slowly. Hence it would appear that in order 
not to injure the young leaves and inflores¬ 
cence it is necessary to take care to apply tlio 
remedy in dry weather.—M. 
HOW TO GROW ACHIMENES. 
TITHE genus Achimenes consists of stove- 
flowering plants of great beauty, which 
well repay cultivation. They are tube- 
^ rous-rooted plants, dying down an¬ 
nually, and requiring a season of rest after the 
foliage has decayed. Unfortunately, they are 
apt to be overlooked at this stage, and when 
this happens the scaly tubes become shrivelled, 
and lose much of their strength. An eminent 
cultivator recommends that as the plants ad¬ 
vance towards maturity, and begin to show 
signs of decay, water should be withheld 
gradually, so that the tubercles do not get 
starved before the leaves have failed ; and as 
soon as the tops are quite dead the pots con¬ 
taining the roots should be removed and 
stored upon their sides, in a warm situation 
where no moisture can reach them, until 
wanted in the following spring. 
A light, rich, sandy, porous soil best suits the 
Achimenes. That recommended by Mr. B. S. 
Williams, in his Stove Flowering Plants, is 
composed of “ peat and leaf-mould in equal 
parts, along with a sixth part of sheep manure 
v r ell decomposed, and enough silver sand to 
give the whole a w r hite appearance.” This 
