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.
Any experiment that tends to throw additional light upon the disease in potatoes, is deserving of consideration, because, although it may not explain the cause satisfactorily, yet it is only by the accumulation of facts, such as the apparent influence of divers modes of growth upon it, that we can hope at last to trace out the principles upon which the presence or absence of the disease is dependant. A. Mons. Bayard has communicated to the horticulturists of Paris, the result of an experiment made by him in an altogether new direction, the result of which he gives in the following account: "Upon my property in the commune of Jaille-Yron, in the department of the Maine and Loire, the potatoes grown in 1850 were generally bad. Before planting, in 1851, I cut some potatoes into sets, and forced into each set, according to its size, one, two or three dry peas. A piece of ground was planted with these sets, and an adjoining piece with sets without peas. Notwithstanding the dry summer, the peas grew strong and flowered, and the potato stems pushed vigorously. The potatoes containing peas produced a crop without disease, which kept well through the winter, and part of them were used the present year in June, for sets. Part of the crop of the sets planted without peas, were diseased.
Whilst the above ex periment was going on in a field of heavy land, a similar one was made in a kitehen garden, where the soil was light, and the result was the same. The potatoes with peas were healthy. but those without rapidly indicated signs of ill-health. During the growth of the pea stems and potato stems, some were pulled up and examined, and it appeared that the early vegetation of the pea had carried off the excessive humidity from the potato." Assuming that upon repetition this experiment in other parts, is found to give the same results, there can be little doubt that the concluding sentence indicates the cause, namely, the absortion by the roots of the peas of a portion the water contained in the sets. This is a strong evidence in favor of the correctness of the now very general opinion, that excessive moisture has much to do with the disease. M.