THE CULTIVATOR. 
61 
growth, and before they have blossomed, sometimes take 
the Yellows. For this reason, many suppose the disease 
to be hereditary. Upon this point, my observation has 
not furnished me with facts that seem conclusive. Icoung 
trees from a diseased parent do indeed take the Yellows; 
so do those from a healthy parent; and one, as appears 
to me, is as liable to do so as the other. At present, it 
may be best to consider this point not settled. 
Sec. 14. Whether the disease is communicated from 
tree to tree through the medium of the blossoms, as is be¬ 
lieved by many, is also an unsettled point. I have not 
known a case where such a communication of disease 
was clearly proved. On the contrary, there is some ne¬ 
gative evidence that throws a doubt upon the correctness 
of the supposition. I took a blossom from a diseased 
tree, and applied the dust (pollen) to the blossom of a 
young tree in my garden. The tree, thus exposed to in¬ 
fection, showed no mark of disease, either in that or the 
succeeding year. 
Sec. 15. If a bud from a diseased tree is innoculated 
into a healthy stock, whether peach, apricot or almond, 
the stock will become diseased and die. As this is a fact 
of some importance, I will furnish some evidence of it. I 
took some buds from a tree,- having symptoms of the 
Yellows, and inserted part into peach, part into apricot, 
and part into almond stocks. Some of the innoculations 
took well, but all showed marks of disease the next sea¬ 
son. The peach and almond stocks, with their buds, died, 
the second winter after innoculation. One apricot stock 
lived five years, but its peach top grew in that time to be 
only about 3 feet high. Further proof is furnished by a 
communication to the “ New-York Farmer,” some years 
ago from David Thomas, of Western New-York, I be¬ 
lieve Cayuga. “ In 1823 I procured,”* he says, “ a box 
of peach trees from the neighborhood of New-York. I 
observed some of these to be of feeble growth; and fear¬ 
ful of losing kinds so rare and so high priced, I budded 
some into a most thrifty stock in the nursery, and some 
into thrifty trees in my peach orchard. On the young 
stock, two buds took, but never sprouted; and in less than 
a year it dwindled like the tree whence the buds were taken, 
and died. Every tree in my 'peach orchard so budded, has 
been long since dead, and no other peach trees have died 
in that orchard.” 
Sec. 16. In an orchard or garden, containing both old 
and young trees, the young trees will generally be diseas¬ 
ed first, the old trees last. 
Sec. 17. From the very limited opportunity which I 
have had, to compare the liability to disease of different 
varieties of peaches, I incline to the opinion that the 
Connecticut Red Rareripe and the Early Ann, are the last 
to take the Yellows. Dr. Monson of this city, thinks a 
White Cling, of natural growth, “ endures the longest of 
any in a healthy state.” With the exception of those 
three varieties, all, whether old sorts originated in times 
beyond the memory of man, or new ones sprung the ve¬ 
ry last year from seed, appear equally susceptible of the 
disease. 
Sec. 18. Peach trees budded on apricots, plums, and 
sweet almonds, are liable to the Yellows. 
Sec. 19. Plum trees are not subject to any disease ana¬ 
logous to the Yellows. But the apricot, standing in the 
neighborhood of diseased peach trees, is subject to a sudden 
decline, ending in death, which I can trace to no visible 
cause. The growth of the branches becomes feeble; ma¬ 
nuring, digging, pruning, all have no effect upon the vi¬ 
gor of the tree. Nothing will save it. Yet I have not 
seen upon the apricot, the slender shoots and premature 
ripening of the fruit, which mark the disease of the 
peach. Nectarines are subject to the disease, and show it 
in the same manner as the peach. 
Sec. 20. The following fact gives reason to believe 
that the disease commences in a tree, between the month 
of September and July following. In the month of Sep¬ 
tember, I took buds from a tree apparently in full health. 
The bids, inserted into young stocks, grew thriftily and 
without disease for three years. But the tree, from 
which they were taken, showed marks of disease in July 
following the time they were taken. 
Sec. 21. There is no connection that I have been able 
to discover between the Yellows and the curled leaf, ex¬ 
cept that the leaves of trees, much diseased by the Yel¬ 
lows, do not curl. 
The phenomena attending the development of the Yel¬ 
lows as detailed above, seems to authorize two or three 
inferences—to be made, however with some distrust. 
Mrs. Marcet (Conversations on Vegetable Physiology,) 
thus explains the formation of the green color of leaves. 
<e The direct rays of the sun are necessary to enable plants 
to decompose carbonic acid. In this process, the oxygen 
of the carbonic acid is exhaled by the leaves, amt the 
carbon deposited in the plant: now, it is this deposition 
which produces their green color. Mr. Sennebien is of 
opinion that carbon is not positively black, but of a dark 
blue color. The cellular tissue of plants is of a yellow¬ 
ish white; consequently, when those minute blue parti¬ 
cles are lodged within the yellow cells, the combination 
cf the two colors produces green, in which the blue or 
yellow tint prevails, in proportion as the carbon or cel¬ 
lular tissue predominates.” Assuming this to be correct, 
.and taking into consideration that the slender shoots, 
which are the marks of disease, grow without forming 
solid wood, (Sec. 1,) and considering that their leaves 
are destitute of green color, though exposed to the light, 
we conclude that they do not decompose carbonic acid, as 
. healthy shoots and leaves do— their particular vital powei 
seems to be prostrated or greatly debilitated. Then, as to 
the fmit, according to Lindley, (Theory of Horticulture) 
the food, upon which fruit subsists and by which it is 
perfected, requires to be elaborated, first in the leaves, 
and then in the fruit. As far as I have observed, the 
leaves of the terminal branches in the early stages of disease 
perform their functions regularly, (Sec. 6.) They have 
a healthy color, are of natural size, and the branches 
grow with unimpaired vigor. The fruit also appears to 
be abundantly supplied with food, (Sec. 3.) Hence it 
seems probable that it is the elaboration of food in the 
diseased fruit, which is imperfect. Lindley says,— 
“among the immediate causes of the peculiar changes 
that occur in the secretions of fruits, are heat and light; 
without which the peculiar qualities of f ruits are imper¬ 
fectly formed.'” He further says, that fruits owe the pro- 
, duction of their sugar, their sweetness, to exposure to 
bright light, decomposing their carbonic acid and expelling 
their oxygen. Therefore, as the fruit of diseased trees is 
exposed to the usual light and heat of our climate, and 
yet has an unnatural purplish red color (Sec. 4,) showing 
that the oxygen is not properly expelled; and forms very 
little sugar or flavor, (Sec. 5,) showing that it does not de¬ 
compose carbonic acid, as it should do; we conclude that 
the particular vital power of the fruit, also, is prostrated 
or debilitated, in the same manner as that of the shoots. 
What has produced this prostration or debility ? For 
myself I must answer, I do not know. Whatever it be, 
it seems not to pervade the whole tree at once—to be lo¬ 
cal in its beginning, and to become general by degrees, 
(Sec. 6)—and capable of passing by contact, perhaps in 
that way only, (Sec. 14,) from one tree to another, (Sec. 
15.) Can it be a poison ? So little is known of the ac¬ 
tion of poisons upon plants, that we can hardly be justifi¬ 
ed in pronouncing positively this unknown something to 
be poison. But there is some analogy, not very striking 
however, between the action of this something upon the 
vital forces of the peach tree, and that of narcotic poisons 
i upon the functions of the animal system. On the suppo¬ 
sition that it is a poison, whence can it be derived ? I 
think not from the soil, (Sec. 8.) I think not from the 
atmosphere, (Sec. 12.) This breaking out of the disease 
in patches, seems to negative the idea of an atmospheric 
origin. I think it is very doubtful whether the disease 
springs from contagion, disseminated by blossoms, (Sec. 
14.) It cannot, I think, be owing to particular sorts of 
peaches having been propagated for a long period, and 
beyond their natural term of existence, (Sec. 13 and 17.) 
It may be remarked that the Early Ann mentioned in 
Sec. 17, is one of our oldest sorts. I think the disease 
cannot be ascribed to defective cultivation, to injudicious 
pruning, or injury to the roots of trees; for there was 
abundance of such cultivation, pruning and injury to roots, 
long before the “Yellows” made its appearance. The 
peach worm, cannot, I think, be charged justly with this 
mischief; for thousands of trees have had the Yellows, 
