This section is from "The Horticulturist, And Journal Of Rural Art And Rural Taste", by P. Barry, A. J. Downing, J. Jay Smith, Peter B. Mead, F. W. Woodward, Henry T. Williams. Also available from Amazon: Horticulturist and Journal of Rural Art and Rural Taste.
Many causes bare been assigned for the disease in question, none of which, so far as my information extends, are satisfactory. Some have supposed it to be occasioned by diseased sap, or vegetable ulcer; some, that it is the work of the curculio; others, with more plausibility, assert that it is the result of poison infused by the minute sting of an insect But none of those entertaining the latter opinion have described the kind of insect, or its characteristics; and it is therefore fair to assume that their belief rests upon conjecture alone. The latter opinion, however, with the exception of the minuteness of the sting, is correct. It will be permitted me to say, that I believe myself to be first in determining the fact, and in ascertaining, certainly, the , habits and character of the insect. I will, therefore, proceed as briefly as may be, and without regard to possible charges of egotism, for asserting in opposition to many scientific men on the subject, what I know beyond a doubt to be the origin of the excrescence, or tumor, and to describe the insect which causes it, its habits, and the best method of guarding against its attacks and increase.
The insect here referred to belongs, I believe, to the Hymonoptera class, and is about an inch in length; color, pale yellow; has four wings, and hind legs resembling those of the grasshopper, which seem designed for similar use; and, although furnished with wings, it uses them only, bo far as I have discovered, for calling, its mates. This it effects by shrill notes through the medium of vibrations, created by a rapid motion of them, and which affords the means of tracing it. The abdomen of the female is much larger than that of the male, in the extremity of which is concealed a sting of about a quarter of an inch in length, with which it pierces any shrub or limb selected as a receptacle for its eggs - often numbering a dozen or more, which are deposited with some acid poison in seperate cells, longitudinally. From these eggs the larvae are hatched - change to the pupae, or chrysalis state, and emerge during the ensuing June.
The excrescence does not appear until after the escape of the insects, the swelling of which is caused by the circulation of the sap being arrested in its natural course by the poison infused, which flows round "the punctured parts, extravasates, and gradually forms the tumor. On dissecting one of these tumors, a grub may be sometimes found, but it does not cause the excrescence. Any one may satisfy himself of the truth of the foregoing remarks by observing the appearance of the insect during the months of August and September, especially the latter, that being the season of coition, when it may be found making its deposits; these, on being completed, are varnished over with a water-proof substance, presenting a dark, glazed appearance, by which it may be known, and on carefully splitting a stung limb in the direction of the perforations early in June, the insect may be found in the larvae state.
I have carried on for two years past a war against this insect, and never suffer one to escape when it can be traced; which, together with a judicious application of the knife in cutting off, and out, all the affected parts so soon as they appear and burning them, I manage to preserve and keep my trees clear of the unsightly tumors. If all those who are interested in the growth and preservation of those trees would adopt the course pursued by me, this destructive insect might, in time, be exterminated, or its effects, at least, very much lessened. Indeed, unless something be done to arrest its progress, many years, in my opinion, will not elapsed ere the cultivation of the Plum and Cherry will have to be abandoned.
* This paper was read before the the Utlca Scientific Association the post winter.
D. B. Wier says, in a Western journal, that the way to prevent the black knot, is to avoid planting on heavy and wet soil; if it appear, cut off all the affected parts in May or June, and cover the wounds with a thick paint of white lead, turpentine and oil. Ho also advises planting the Wild Goose plum and other varieties of the Chickasaw family, which do not bear black knots.
VIEW OF LAKE AND PAGODA ISLAND, VICTORIA PARK. LONDON.