This section is from the book "The Gardener's Monthly And Horticulturist V22", by Thomas Meehan. See also: Four-Season Harvest: Organic Vegetables from Your Home Garden All Year Long.
The September number of the Gardener's Monthly contains a notice of the Annual Meeting of the Georgia State Horticultural Society, and upon the subject of the relation of the apple leaf fungus to that producing "cedar apples," you remark that "Unfortunately, little is known of the manner in which Roestelia works, so that no one can suggest any remedy. The fungus which makes the 'apple' on the Cedar is the Podisoma, and has no relation to the Roestelia "
That Roestelia and Podisoma are but two stages of one fungus has been the opinion of those who have carefully studied them in both the laboratory and orchard. In proof of the former, I beg leave to refer to the proceedings of the Danish Academy of Sciences, an abstract of which is given in the American Naturalist,Vol. II, page 557, and to Sach's Botany, page 246. The most recent of our botanical works, Bissey's and Plant's, state unhesitatingly, the general acceptance of this matter of "heteroecism" among the fungi.
Of cases coming to the notice of orchardists, that which I communicated to the February number of the American Agriculturist (1880), and is referred to in this meeting of the Georgia Horticultural Society, is the best, though not the only one, of which I have knowledge. In this instance the attack upon the fruit as well as the leaf was very marked, and shows a danger, which under circumstances specially favorable to the development of fungi, may prove very great.
I believe we know enough of the nature of Roestelia, and the manner in which it works to suggest as a remedy, the destruction of all Cedar trees which have become infested with " Cedar Apples," especially when they are in the immediate neighborhood of orchards.