REPORT OF THE SUPERINTENDENT OF GARDENS. 197 
reach maturity. So far as heat and cold are involved in temperatures, 
this criterion is probably nearly correct, the amount of heat necessary 
to insure a crop of corn being also sufficient to mature most of the varie- 
ties of cultivated grapes which have been derived from our native north- 
ern species, but the numerous failures in profitable grape culture prove 
that other factors besides those of heat and cold have an important in- 
fiuence upon the health of a vineyard. 
To those who are conversant with the history of the progress of grape 
culture in the United States for the pasi thirty years, and have acquainted 
themselves with the causes of varying failures and successes, it must 
seem difficult to account for the fact that grape growers in general have 
been slow, and apparently unwilling, to recognize the true reason for 
most of the failures which occur. In some of the earliest reports of the 
Department of Agriculture the statement was dwelt upon that the 
greatest obstacle to complete success in grape culture could be referred 
to the deterioration of the plants consequent upon the injury they sus- 
tained from mildew on the leaves. This explanation of failure was not 
generally considered as conclusive. Both grape growers and authors 
of treatises on grape culture, especially the latter, usually referred fail- 
ures to some other cause or causes, which were expressed by the phrase 
“improper treatment,” and this was considered a sufficient answer to 
all inquiries regarding failures. 
This profound explanation was generally accompanied by the further 
advice that by giving vineyards “ proper treatment” they would be ex- 
empt from failure or loss. When called upon to define “improper” and. 
“‘ proper” treatment, the answers would be often contradictory, and more 
frequently unsatisfactory. This want of recognition of the true source 
of trouble has been greatly against progressive grape culture. Varie- 
ties of grapes much lauded for their superior qualities have been procured 
at great expense and extensively planted, the result only adding another 
disappointment to the planter. The main cause of failure has been fre- 
quently pointed out, and from time to time the department has published 
lists of those varieties best adapted to general culture, as also those 
which require special localities, and further experience has borne con- 
clusive evidence of the value and accuracy of these reports. It was dis- 
tinctly shown, and it is now clearly admitted, that the distinguishing 
feature of a good grape climate is that where there is an entire absence 
of mildew on the foliage or on the fruit of the vines. While making this 
statement somewhat prominent it is not forgotten that heavy losses are 
occasioned by rot in the berry. This disease is not, however, confined to 
varieties subject to leaf mildew, but it is equally prevalent in those which 
are rarely attacked by it. The causes of mildew are solely atmospheric, 
while those favoring rot are more intimately connected with the chemical 
and physical condition of the soil and the growth by the roots. We need 
no stronger proof of the influence that the presence or absence of mildew 
on the leaves of our native grapes has upon the determination of their 
value, than to turn to the list of the varieties which are most extensively 
cultivated, when it will be found that they are valued more because of 
their freedom from disease than from the qualities of their fruit. 
Again, it is clearly ascertained that. the most fatal species of mildew 
is caused by dampness, so that the further statement may be made that 
where we find a locality in which grapes are specially remunerative, we 
will find that its climate is characterized by the absence of heavy dews. 
It is only in these latter localities and under their special conditions that 
the best varieties afford a profitable return. Where heavy dews prevail 
during the summer months it has been found unsatisfactory to cultivate 
