1848 
THE CULTIVATOR. 
303 
TOE POTATO DISEASE, &c. 
Editors Cultivator-™! am sorry to announce to 
you the undoubted existence of the u Potato Disease” 
among us. I have been confidently looking for its ap¬ 
pearance for some days past, as we have had, since the 
30th of May, precisely those alternations of weather 
which have invariably accompanied it in former years. 
From May 30th to June 9th, (with the exception of 
warm showery weather on the 3d and 5th,) the weather 
was almost constantly cold and drizzly. During this 
period (June 1st,) we had a slight touch of frost. From 
June 11th to 13th, inclusive, the weather was very bad, 
the thermometer sinking just to freezing point at night 
on the 13th, and the days exhibiting a dry lacerating 
chilly wind, that injured ail tender plants very much. 
From the 15th to the 19th we had five very warm 
days, followed, on the last day, by copious rain. On 
the 23d and 24th, the wind was so rough and cold as 
to make it necessary to cover melons, &e., wherever it 
was possible. This was succeeded suddenly by hot 
weather on the 26th and 27th. 
Lastly, from July 4th to 10th, we had one continued 
chill, making it necessary to cover tender plants, such 
as melons and cucumbers, as much as in the month of 
May. The difference in the weather between this and 
the years ’44, ’46 and ’47, when the potato disease 
prevailed so extensively, has been, that the changes 
have been much more numerous than in those years, but 
not quite so severe. The thermometer has not usually 
sunk so low, nor the wind been so lacerating to vegeta¬ 
tion. Especially the severe chills that occurred from 
the 11th to the 15th of July, 1846; and again from the 
11th to 21st of June, and from the 24th of July to the 
3rd of August, 1847, (all of which preceded periods of 
potato disease,) were more severe than those of the 
present year. 
The morbid indications on the potato now first, just 
becoming visible, are three: a steel blue coloring on the 
points of some of the upper leaves,—a rusty look on 
those that are lower and central in the hill, together 
with a single withered leaf on the apex of the plant, 
especially of such spires as exhibit no blossoms. This 
withered leaf, together with the others exhibiting mor¬ 
bid indication, speedily become dry. 
£ As the depression of the temperature has not been so 
low, nor continued for so long a time as in former years, 
when the potato was diseased., so I hope the morbid ap¬ 
pearance will not increase rapidly, but gradually yield, 
under mild steady weather, until a healthy action is re¬ 
stored to the system of the plant. 
If such should be the result, the potato will live out 
its natural life, or nearly so; and on digging in the au¬ 
tumn, we shall discover only occasional traces of dis¬ 
ease on the tubers. Nothing is more evident to care¬ 
ful observers of the progress of this disease, than the 
fact that it does not originate locally in the tuber, but 
is the result of morbid secretions in the plant itself ; 
and that hence, in point of time, the disease of the tu¬ 
ber follows that of the herbage. Should it be asserted 
that disease has sometimes been known to succeed hot 
showery weather, (as is probably the fact,) when none 
of the foregoing morbid indications appeared, still the 
existence of a morbid condition of the secretions of the 
plant is then just as undoubted. 
The mode by which severities of weather produce 
this disease is, I think, obvious. The brightness and 
warmth of our summers, approach very near to those 
of the tropics. Hence all those tropical and semi-tro¬ 
pical plants that mature their fruits in from 12 to 20 
weeks, and do not require the highest heats of these 
regions, may be raised here with tolerable success, in 
an ordinary season. Melons, cucumbers, squashes, 
pumpkins, corn, beans, egg-plants, tomatoes and pota¬ 
toes, are all of this class. The potato being moreover 
a native of the mountains of the tropical regions, pre¬ 
sents itself among us already, by that fact, half accli¬ 
mated. 
Now, soil being left out of the account, the first re¬ 
quisition, in this whole class of plants, is heat and light ; 
just as air and moisture are to our hardy ones, such as 
cabbage, turneps, the grasses, and the grains. 
The Potato, however, requires less heat and more 
moisture than any other tender plant we cultivate, and 
so presents points of similarity to our half hardy ones. 
While this class of plants enjoy steady warm and 
bright weather, they are sure to grow with any tolera¬ 
ble culture. But let sudden changes occur; as that of 
high and dry heats succeeded by long and damp chills, 
and the deprivation of their nutrimental juices is ine¬ 
vitable. This, attended with the laceration of foliage 
by the wind, and the sudden return of warm weather, 
producing a ruinous perspiration from the foliage before 
the earth is warm enough adequately to restore the cir¬ 
culation of the plant, finishes the work of death. Any 
or all these causes occurring in mitigated forms and 
degrees, produce proportional results of unfruitfulness 
and disease. In such ways the vital force of the plant 
yields to the stronger influence of chemical action. 
Had those who have speculated on the causes of the 
potato disease cultivated the small list of tropical plants 
noticed above, though but for a single unfavorable sea¬ 
son, side by side; and had they at the same time, heed¬ 
ed the well ascertained physiological laws of tender 
plants, they would, I think, have come unanimously to 
this single and simple conclusion, that all tropical 
plants cultivated here, suffer usually and mainly from 
infelicities of weather, especially damp chills; and 
that the morbid indications in this whole class of plants 
are as nearly the same as the difference of foliage and 
fruit will permit. Hence I would as soon talk of To¬ 
mato, or Melon, as of Potato disease. The only pecu¬ 
liarity in regard to the potato, is the recency of its 
marked liability to disease. Indeed, such are the unal¬ 
terable laws of vegetable physiology, that had we a 
minute history of the potato, as cultivated a century 
ago in our own land, we should, I doubt not, find fre¬ 
quent slight traces at least of its present morbid mani¬ 
festation. 
But I did not intend now to write an essay on this 
subject. Let those who would see the illustration and 
proof of the foregoing positions consult a treatise on 
the subject, contained in the u Transactions of the 
New-York State Agricultural Society, for 1847,” now 
just published. 
July 22nd. The indications of disease on the herbage 
of the potato, is now everywhere apparent; although 
its progress has been much less rapid than in 1846, or 
the second attack in 1847. On the day of the prece¬ 
ding date, (July 14th,) we had a shower of rain fol¬ 
lowed by chills and wind of considerable severity and 
continuance, so that I feared they would enhance the 
morbid tendencies pre-existing. 
August 8th. Under the last preceding date, we en¬ 
joyed a fine warm rain succeeded by cool, but not cold 
weather. Under its influence, the influence of disease 
seems clearly lessened; while those leaves that had be- 
