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ARBORETUM AND FRUTICETUM.

PART III

early as seven or eight 2266

years after planting,and in all it seems toproceed with the great-est rapidity; some-times destroying the itrees entirely, between i15 and 25 years old,on soils in which theoak prospers. (Seep. 2376.) With regardto the cause of thisdisease, it is by most planters attributed to the soil and situation; and bysome to improper management. The latter seems to be supposed to con-sist chiefly in improper pruning, that is, cutting off part of its roots in theprocess of planting, or depriving the tree of part of its branches in theearly stages of it growth. The rot in the larch, Mr. Gorrie observes, “ hasbeen found to prevail on rich deep soils, and in poor shallow soils, onretentive and porous subsoils, on soils incumbent on freestone, limestone,and whin, or green, stone; and, also, on all these descriptions of soil andsubsoil, the larch has been found tolerably free from this hidden disease. Thisbeing the case, we are led to suppose that the rot in larch takes its rise fromsomething accidental, rather than from any natural property in the soil. It hasbeen a common practice to follow a crop of Scotch pine with this more loftyand promising plant; and the writer of this has recently discovered, in nume-rous instances, that, where this has taken place, the rot uniformly commences infearfully numerous instances. This effect is produced as soon as 7 or 8 yearsafter planting; while plantations of the same plant, on the same estate, planted atthe same period, and in every respect similarly circumstanced to the other,with the important exception that they did not follow the Scotch pine, con-tinue entirely free from the rot. In old plantations, too, where the Scotchpine and larch had been mixed together, and where the disease was by nomeans prevalent, the new crop of larch was completely affected; giving roomto infer that the rotting roots’of the Pinus sylvestris, or Scotch pine form, atleast, one powerful agent in promoting this disease.” (Gard. Mag., vol vii.p. 574.) In the Quart. Jour, of Agri., vol. v., Mr. Gorrie repeats the aboveobservations, and adds: “ In this opinion I am supported by my esteemedfriend, Mr. James Young of Pitfour, whose sound judgment and practicalskill place him high in the estimation of his professional brethren.” Mr.Gorrie then gives some extracts from a communication by Mr. Young, fromwhich it appears that Mr. Young, when thinning out a plantation of younglarches, (which had been planted as nurses to oaks, and had succeeded a crop ofScotch pines,) found the proportion of decaying plants about 6000 to 50;while larches in the neighbourhood, on similar soil, but not succeeding theScotch pine, were found, when cut down at 60 years’ growth, “ to be ofexcellent quality, only one in six or eight showing slight symptoms of thedisease.” Mr. Young adds that he cannot bring himself to believe thatthere is anything deleterious in the soil naturally; but that he thinks it pos-sible that the Scotch pine “ roots, in the course of decay, after the treeshave been cut down, may have communicated some poisonous quality to thesoil, which promotes or originates this disease in the larch.” Mr. Websterobserves that the disease is most prevalent in plantations of the larchwhere the trees are planted so closely together as not to admit a free circu-lation of air. Mr. Munro thinks it probable that an extensive annual deposit otalbumen, when the tree is young, is the cause of the rot. (Gard. Mag., vol.p. 555.); but Mr. Gorrie has shown (Ibid., vol. x. p. 546.) that this is notlikely to be the case. Mr. Matthew, finding the rot in trees which habeen chilled in wet cold clays, and in others which had been starved in drysand, and, again, in the most luxuriant-growing plants, in open situations,