40 STATE POMOLOGICAL SOCIETY. 



CAUSE OF THE YELLOWS. 



No writer has yet ventured to assign a theory, supported by any facts, whicli 

 would explain the cause of this malady. We therefore advance our opinion 

 with some diffidence, but yet not without much confidence in its truth. 



We believe tlie malady called the Yellows to be a constitutional taint exist- 

 ing in many American varieties of the peach, and produced, in the first place, 

 by bad cultivation and the consequent exhaustion arising from successive over- 

 crops. Afterwards it has been established and perpetuated by sowing the seeds 

 of the enfeebled tree, either to obtain varieties or for stocks. 



Let us look for a moment into the history of the peach culture in the United 

 States. For almost a hundred years after this tree was introduced into this 

 country it was largely cultivated, especially in Virginia, Maryland, and New 

 Jersey, as we have already stated, in perfect freedom from such disease, and 

 with the least possible care. The great natural fertility of the soil was unex- 

 hausted, and the land occupied by orchards was seldom or never crojiped. 

 Most of the soil of these States, however, though at first naturally rich, was 

 light and sandy, and in course of time became comparatively exhausted. The 

 peach-tree, always productive to an excess in this climate, in the impoverished 

 soil was no longer able to recruit its energies by annual growth, and gradually 

 became more and more enfeebled and short-lived. About 1800, or a few years 

 before, attention was attracted in the neighborhood of Philadelphia to the 

 Eudden decay and death of the orchards without apparent cause. From Phila- 

 delphia and Delaware the disease gradually extended to New Jerse}^ where, in 

 1814, it was so prevalent as to destroy a considerable part of all the orchards. 

 About three or four years later it appeared on the banks of the Hudson (or 

 from 1812 to 1815), gradually and slowly extending northward and westward 

 to the remainder of the State. Its progress to Connecticut was taking place at 

 the same time, a few trees here and there showing the disease, until it became 

 well known (though not yet generally prevalent) throughout most of the 

 warmpr parts of New England. 



It should be here remarked, that though the disease had been considerably 

 noticed in Maryland and the Middle States previously, yet it w^as by no means 

 general until about the close of the war of 1812. At this time wheat and other 

 grain crops bore very high prices, and the failing fertility of the peach orchard 

 soils of those States was suddenly still more lowered by a heavy system of crop- 

 ping between the trees without returning anything to the soil. Still the peach 

 was planted, produced a few heavy crops, and declined from sheer feebleness 

 and want of sustenance. As it was the custom with many orchardists to raise 

 their own seedling trees, and as almost all nurserymen gathered the stones 

 indiscriminately for stocks, it is evident that the constitutional debility of the 

 parent trees would naturally be inherited to a greater or less degree by the 

 seedlings. Still the system of allowing the tree to exhaust itself by heavy and 

 repeated crops in a light soil was adhered to, and generation after generation 

 of seedlings, each more enfeebled than the former, at last produced a com- 

 pletely sickly and feeble stock of peach-trees in those districts. 



The great abundance of this fruit caused it to find its way more or less into 

 all the markets on the sea-coast. The stones of the enfeebled Southern trees 

 were thus carried north, and, being esteemed by many better than those of 

 home growth, were everywhere more or less planted. They brought with them 

 the enleebled and tainted constitution derived from the parent stock. They 

 reproduced almost always the same disease in the new soil ; and thus, little 



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