348 
AMERICAN AG-RICIILTURIST. 
[September, 
about $11,000. The highest price for a single speci¬ 
men was about $190, while great numbers were sold 
at prices ranging all the way from $40 to $60 each. 
The American Grape Mildew. 
In order to become more thoroughly acquainted 
with the prevalence of Grape Mildew, the writer, 
in the summer of 1877, sent a list of questions to 
the leading grape growers in the country. From 
the replies, many of which were very full, it was 
evident that in the mildew , the grape growers have 
a serious and destructive pest. The literature of 
the subject shows that it is no new thing, and that 
grape mildew has received considerable attention 
Fig. 1.— A GRAPE LEAP WITH MILDEW'. 
from horticultural writers. [Just as we are prepar¬ 
ing this paper, there comes to hand a quantity of 
dwarfed, discolored, and worthless grapes, made so 
by this destructive mildew fungus.] All who have 
given any attention to the matter, are aware that 
the mildew is a minute fungus, known to botanists 
as Peronospora viticola. This fungus is best observed 
on the leaves, where it makes yellowish-brown 
patches on the upper side, while beneath there is a 
white forest of the spores. The smooth-leaved va¬ 
rieties show the mildew to the best advantage, as it 
is not obscured by the dense growth of hairs of the 
“ woolly ” varieties. Figure 1 is a view of the un¬ 
der side of a grape leaf, reduced in size, showing 
the affected portions darkened, a , b. If a thin cross- 
section of the leaf is made through one of these 
mildewed spots, and placed under a compound mi¬ 
croscope, we have what is shown in figure 2. (For 
convenience, the under side of the section is placed 
uppermost in the engraving.) The threads of the 
fungus, c, run in all 
directions between 
the cells of the leaf, 
and after a short time 
reach the breathing- 
pores, or stomata, b. 
(An account of these 
pores is given on 
page 306,last month.) 
The threads of the 
fungus pass out, and 
reach the air, through 
these breathing pores 
of the leaf — often 
half a dozen from a 
single “ pore ’’—and 
branch so as to ap¬ 
pear like a miniature 
tree, a. Upon the tips 
of these branches, the 
spores, d, d, are rapid¬ 
ly formed. It is the 
vast multitude of 
these little branched 
tops,with their clear transparent spores, which gives 
the white, frosty appearance of the infected spots, to 
the naked eye. Figure 3 shows a highly magnified 
view of a small portion of a thread of the fungus, 
e, after it has pushed its way between the cells of 
the leaf, in which is also seen some of the numer¬ 
ous little projections, i, i, which penetrate the cell- 
wall and absorb the nourishment. From their func¬ 
tion they have received the common name of 
“suckers.” One of the ultimate extremities of 
a “limb” is shown in figure 4, with its peculiar 
form of branching, d, together with one of the 
spores, g. These are 
non-sexnal spores, 
(see article in July, 
page 208), and have 
a peculiar method of 
germination. The 
contents of the spore, 
a few hours after it is 
ripe, divide into from Fig. 3. —filament and 
six to ten oval bod- “suckers.” 
ies, g, which soon rupture the spore-wall and es¬ 
cape, each provided with two little hair-like pro¬ 
cesses, k, by means of which it can rapidly move 
about. Here, then, we have each spore producing 
a number of moving bodies, which, after finding a 
suitable locality, germinate and reproduce the mil¬ 
dew in a new place, and it maybe on another plant. 
Besides these non-sexual spores, just described, 
there is another land always formed within the tis¬ 
sue of the grape plant, and is sexual, as it is neces¬ 
sary that the contents of two different threads 
should mingle in order that one of these spores 
may arise. This process is shown in figure 5, the 
small filament, a, representing the male, the con¬ 
tents of which passes into the female cell, b, which 
afterwards forms a sexual spore, c. These spores are 
large, and covered with a thick cell-wall, slow in 
their formation in comparison with the exceedingly 
rapid development of the aerial, non-sexual spores. 
They are only produced late in the season, aud 
serve the special purpose of carrying the mildew 
over the winter. They germinate in the same way 
as the small summer spores, by producing a num¬ 
ber of motile bodies— 
which, when finding 
their way to the grape 
plant,repeat the trouble 
of the previous year. 
This Mildew makes 
its appearance any time 
from the first of June 
to the last of Septem¬ 
ber, depending very 
largely upon the state 
of the weather—a suc¬ 
cession of warm rainy 
days being the most 
favorable for its de¬ 
velopment. We have 
often been asked what 
varieties are most susceptible; but the question 
cannot at present be answered. The strong, 
thick-leaved varieties, like the Concord, ap¬ 
pear to be less affected, while some tender thin- 
leaved varieties are almost ruined. Although this 
mildew is peculiar to America, it flourishes up¬ 
on foreign vines, when brought to this country, 
“ even more luxuriantly than on American species.” 
The mildew of Europe, which, at times, has proved 
so disastrous in the vineyards of Maderia, is a fun¬ 
gus of a very different kind from this, and de¬ 
mands separate consideration, as we have it also. 
Flowers of Sulphur, used with a bellows, (fig. 6), 
earlg in the season , when “ an ounce of prevention is 
worth a pound of cure,” followed by repeated dust¬ 
ing as circumstances of weather, etc., decide, is the 
remedy for the grape mildew. “ Early and over¬ 
bearing are prolific sources of mildew,” therefore 
judicious thinning will do much to keep it off. 
The Uses of the Flower-Pot. 
BY PETER HENDERSON, JERSEY CITY HIGHTS, N. J. 
The past 20 years has shown great, changes in the 
method of growing plants in this country for com¬ 
mercial purposes, and it may be said that the rais¬ 
ing of some plants has been completely revolution¬ 
ized. One example of this is seen in the present 
method of striking strawberry plants in pots. Al¬ 
though pot-layering of strawberries was begun 
about 20 years ago, by the late Mr. Knox, of Pitts¬ 
burgh, Pa., yet it was only done to more certainly 
increase some of the newer sort’s, and not for the 
purpose of producing plants for genei-al cultiva¬ 
tion. Now this pot-layering has become so popu¬ 
lar, that an amateur cultivator rarely plants for 
his own use any other than pot-grown plants. 
Hundreds of thousands of pot-grown strawberry 
plants are sold in New York City during the 
months of August and September to those having 
gardens in the suburbs. I am so satisfied of the 
advantages of this plan, that if I were intending to 
grow strawberries for market, no matter to what 
extoi)t, I would adopt this method. During the 
past five years we have never failed to get a full 
crop of fruit from pot-grown plants, if set out be¬ 
fore August 15th, and have had a half crop even if 
set out as late as the middle of September. But it 
is not alone in strawberries that the flower-pot pre¬ 
sents great advantages to the propagator. Grape¬ 
vine cuttings put in the propagating greenhouse, 
or hotrbed, on April 1st, will be ready to pot in a 
3-inch pot ir May, aud these, if shifted into Tinch 
Fig. 5.— FORMATION OF SEXUAL SPORE. 
pots in June, will make plants 4 feet high by fall, 
having their roots a dense mass of fibres. With 
vines thus grown, both tops and roots are thor¬ 
oughly ripened, and, when set out either in fall cr 
spring, such plants never fail to start, and make 
twice the growth that a vine of the same age 
would have done, if it had been merely lifted from 
the nursery row without being pot-grown. More¬ 
over, when grown in pots, vines can be transplanted, 
if desired, during the hottest and driest days of July 
or August, with perfect safety. The same is true 
of various other vines, such as all kinds of Honey¬ 
suckles, Clematis, Wistarias, and other hardy 
climbing plants. So with the hardy-herbaceous 
plants, such as Chrysanthemums, Phloxes, and many 
others, most of which are now grown in flower¬ 
pots, and can be safely transported and set out at 
any season of the year. Perhaps no plant has 
been so greatly benefited by the method of culti¬ 
vation in pots as the Rose. Formerly roses were 
cultivated in nursery rows, in the open ground, like 
ordinary shrubs. When wanted to fill orders, roses 
were lifted from the open ground and packed like 
other nursery stock. The business of raising roses 
is almost entirely changed, and those engaged in 
supplying the demand grow them in pots. It is 
true that the pot-plant is not so large as that sold 
from the nursery row, but being pot-grown it has a 
mass of fibrous roots, and though the plant may 
not be more than 6 inches high, when put out in 
May, it will make a larger and better plant by Sep¬ 
tember than the nursery plant that has not been 
Fig. 6. —SULPHUR BELLOWS. 
pot-grown, though that may have been perhaps six 
times larger when planted. Moreover, in the pot- 
grown plants, if in healthy condition, there will not 
be over one per cent that will fail to grow, while 
the plants from nursery rows often fail largely, 
even under the best conditions. A rose plant makes 
comparatively few fibrous roots; it has therefore 
weaker recuperative powers than most shrubs, and 
for that reason the thousands who still buy such 
plants are doomed in many cases to disappoint¬ 
ment. Rot-growing is particularly valuable with 
nJl plants that make long bare roots, such as the 
Chinese Wistarias, Magnolias, etc. Many know 
from unpleasant experience that plants of the 
Chinese Wistaria 6 or 8 feet long, taken from the 
open ground, will rarely make much growth the first 
season after planting, often forming shoots only 
6 inches long, and even in the second season the 
