This section is from the book "The Gardener's Monthly And Horticulturist V26", by Thomas Meehan. See also: Four-Season Harvest: Organic Vegetables from Your Home Garden All Year Long.
My previous papers in the Gardeners' Monthly were incidentally the result of asking a question concerning the Editor's experience with oil upon pear trees, and the response being favorable, I was induced not to lose sight of the facts then stated, and prompting me to action by another season's experiments, which, it was hoped, would prove sufficiently demonstrative in effect to make the result apparent, convincing, and - to me - final.
In this continued investigation a characteristic "subject" was selected, but the conditions may be said to be diametrically opposite to that of patients who present themselves for hospital practice and treatment. Here they battle with "disease," and a time often comes when many are known as "incurables," and the decision is whispered in accents of solemnity or indicated by some well-known symbolic hieroglyphic located in a convenient spot for observation. And thus a patient sometimes possessing an instinctive knowledge of the same, manages to hobble out of the institution to the best of his ability, in order to escape any marked attention by experiment that may encourage a much broader scope of treatment.
Now, in my experiment, I selected a strong, healthy "Duchess" (d'Angouleme) with an attractive contour, and firmly established in good soil and sod, and offering but little chance of escape except by the " pelting of a pitiless storm," but which was deemed unworthy of any prognostication. It may appear presumptuous to trifle by experiment with a Duchess favored by such widespread pomological renown; nevertheless, I think the selection a proper one, and, consequently, gave all due study to the case.
In proceeding with this experiment I had a twofold object in view: one being the good or bad effects of the oil; the other, to ascertain, by aid of a thermometer properly attached to the tree, the temperature likely to be encountered during the summer months, and, by this means, establish a precedent for future reference and of special importance, so far as it agrees with the Bacterian theory, which ranges from 900 upwards, though it is now generally admitted that a temperature from 990 to 1060 Fahrenheit is most favorable to influence the development of Bacteria.
I will now proceed to detail the season's experience. On the 24th of April the following application was made and divided off: Upon the lower third of the tree was applied a copious covering of slushing oil; the centre third an equally plentiful application of vaseline; and the upper third a bountiful distribution of raw linseed oil, covering all the buds as in the two previous cases, the tree selected being in a position whereby the full influence of the sun was attainable from its rising to its setting. Times of observation, 6.30 A. M., 12.30 P. M. and 6.30 P. M., as near as practicable. The results were notably these: On the 2d of May on trees which had been allowed to take their natural course, buds showed symptoms of opening, and on the 19th these trees were in full blossom. The tree, however, under experiment, seemed to be in a comatose condition; but on the 27th the tree had fairly conquered, and every bud had leaved out where the linseed oil had been applied, but not so where the vaseline and slushing oil were located; not a bud had survived, while the bark had become gnarled and irregular in appearance. By this you will see that the linseed oil came out victorious, but delayed for several weeks the natural expansion o' the buds.
The property of raw linseed oil is to form a dry film in a short time, and is not otherwise quickly affected, and, from the fact of its universal use in out-door work by painters, it would seem unadvisable to experiment with other oils of which we know but little. There is this, however, noticeable with vaseline and slushing oil, viz.: wherever they may be applied and protected by shade, either on fruit, ornamental or other trees, they retain their moist condition both winter and summer, and have no detrimental effect on the bark, while on the other hand they may be positively designated as bud-killing productions, whether applied in the shade or to the exposure to the sun's rays. Cotton-seed oil forms a dry film upon the bark, but the buds meet with the same fate of extermination as previously mentioned.
With respect to the thermometer observations, an ordinary one was used for the purpose, and properly secured to the tree; but it is evident that had a self adjusting thermometer been employed, the highest temperature could always have been designated and less attention needed, which are two very important factors in such an undertaking. On June 2d the temperature reached 90°, but heard of no blight, though I had made extensive arrangements with others to inform me of the first appearance. On the 5th and 7th the same height and no intimation. On the 8th 94P were reached, accompanied with the sudden phenomena and onslaught of countless numbers of blow flies, house flies and mosquitoes. June 9th showed 960 and no reports; 18th to 24th, consecutively, up to 940, but on the 23d was elevated to 100°, accompanied by a warm thunder shower, and followed by a humid and sultry atmosphere.
At this stage of the investigation I thought it might be profitable to skirmish the outskirts of the city for a case in point. A Seckel was soon discovered, and watched at intervals for ten days, at which time the disease had reached its climax. Not being the owner of the tree, and being too far distant from my residence, no experiment was made; the diseased parts, however, were finally lopped off. Since the last date mentioned to September 10th, the thermometer showed at times from 900 to 1040. On the 10th it was at 970, with slight thunder shower, but too late in the season, I think, to have the dreaded effect of heat of this elevation accompanied by moisture, and now so well understood as the primary and necessary concomitants to the disease.
Experiments with oil have been carried on in England during the past few seasons. There seems to be an issue with those interested in the matter, as to the proper time of application, and that is when the sap is "up" or "down," as they express it. Paraffin is the brand on trial, and with contrary results; the editor of the London Field, however, says it should never be applied except when trees are in a dormant state in winter, and never when the sap is " up".
59 Gregory street, Rochester, N. Y.
[This is perhaps one of the most valuable contributions to the oil topic that has appeared in our pages, and helps to explain some different results in the use of linseed oil that appeared enigmatical before.
As already stated in these pages, the Editor had a large number of pear and apple trees that were literally white with scale. These were painted with linseed oil. Every scale was destroyed, and not only did no harm result, but the trees really seemed invigorated by the application. This was reported in the Gardeners' Monthly, but some readers who tried it on the faith of this report, totally destroyed their trees, and, naturally, felt sore at the advice they received. At the time it was supposed that there might be some difference in the results between raw, boiled, or adulterated oil. Now it appears that whatever difference there may be, still another element of danger presents itself, namely, the penetration of the oil into the bud.
The very satisfactory work on the Editor's trees was done in the winter time, when the buds were wholly at rest, and the oil could not penetrate. We can readily imagine, after reading this communication, that later in the season, when the buds were swelling, the result might have been different. - Ed. G. M].