PEACH YELLOWS. 265 



therefore more easily detected by ordinary observers, or rather not so easily 

 overlooked. In this particular I noticed on the Delaware and Chesapeake 

 Peninsula a very marked difference between 1887 and 1888. In 1888 the 

 diseased trees sent out a scanty growth of the abnormal shoots; in 1887 such 

 growths were very abundant. 



All things considered, the question of the effect of excessive rainfall must 

 be left an open one. Certainly it cannot of itself cause yellows, because dis- 

 tricts only a few miles south of the infected areas suffered from veritable 

 floods of rain and yet entirely escaped the disease. Another season may throw 

 more light upon the subject. It certainly will if it is dry. 



EARTH CONDITIONS. 



The belief that peach yellows is in some way related to poverty of soil is not 

 a new theory. As long ago as 1839 a correspondent of the Farmers' Cabinet 

 stated that in earlier volumes of that journal he had found no less than eight- 

 een papers recommending "alkaline substances for the prevention or cure of 

 the premature decay of pear and peach trees. Two years later Littleton 

 Physic, of Ararat Farm, Cecil county, Md., highly recommended nitrate of 

 potash for peach trees, his experiments having begun as early as 1836. 



In 1848. J. W. Bissel, of Eochester, N. Y., stated that there is a loss of lime 

 and potash in soils where many peach trees have been grown, and suggested 

 that yellows might be due "to the absence or small quantity of these alkalies.'* 

 He had never seen any analyses of the wood, but suggested that such be made. 

 The next year Professor Emmons, of Albany, N. Y., published analyses of 

 healthy and diseased tissues. At this time New Jersey peach growers were 

 also attributing yellows to bad treatment and poverty of soil. They then held, 

 as some of them still hold, that the exhaustion of the land by excessive and 

 unintermitted cropping is a sufficient explanation of the disease. 



An analysis of healthy branches was also published in 1854 by Mr. Kirtland. 



In 1871, Dr. R, C. Kedzie, of Lansing, Michigan, visited Benton Harbor, 

 examined many diseased orchards, and made analyses of healthy and diseased 

 tissues. He found in the diseased tree a deficiency of carbonate of potash and 

 phosphate of lime, but in view of the fact that the composition of the ash of 

 the same plant varies much according to the age of the plant, the kind of soil 

 on which it grows, and the degree of vigor of its development, he declares 

 that "perhaps it might with justice be said that the results of chemical 

 analysis, like those of microscopic examination [Dr. W. J. Beal's], are merely 

 negative." At about that date Thomas Meehan, of Germantown, Pa., stated 

 that Dr. Wood, of the Piiilosophical Society, had found that, potash benefited 

 peach trees attacked by yellows. 



In 1882. Charles Black, a well known nurseryman of Hightstown, N. J., 

 declared that crowding was one of the causes of yellows, and made the follow- 

 ing remarkable statement: ''If your trees are too thick, pull out every other 

 row, and as a rule you will cure the yellows." Trees are sometimes set as 

 close as 8 or 10 feet, but should be 18 or 20 feet apart. 



The same year Dr. Goessman, of Amherst, Mass., published his four analyses 

 in connection with a paper by Prof. D. P. Penhallow on the microscopic 

 characteristics of the disease. Dr. Goessman found in the diseased fruit an 

 excess of lime and phosphoric acid and a deficiency of magnesia and potash ; 

 and in the diseased branches an excess of iron, lime, and magnesia, and a 

 deficiency of potash and phosphoric acid. Both gentlemen took the giound 



