The Canadian Horticulturist. 



WILL FERTILIZERS EITHER PREVENT 

 PEACH YELLOWS? 



OR CURE 





X exhaustive series of experiments have been conducted by 

 Dr. Irwin F. Smith, special agent in charge of the peach 

 yellows investigations of the United States Department of 

 Agriculture, for the purpose of ascertaining whether the 

 peach yellows were caused by soil exhaustion, and whether 

 they could be either prevented or cured by the application 

 of potash salts and superphosphates. These experiments 

 were continued for a period of four years, and the results, 

 with full details, are embodied in Bulletin No. 4 of the 

 Division of Vegetable Pathology, 1893, embracing 197 pages. 



It will be remembered that Professor Penhallow has supported the view 

 taken by Goessman, Fuller, Hale, and others, that by the use of potash salts and 

 superphosphates the peach yellows could be both cured and prevented ; and 

 wide publicity has been given to frequent statements that the results obtained 

 by these means were very satisfactory. In order to thoroughly test this matter, 

 these experiments by Dr. Smith were undertaken and prosecuted on a scale and 

 for a length of time sufficiently extensive to fully demonstrate the truth or error 

 of the view taken and advocated by Professor Penhallow. 



In order to ascertain whether affected trees were suffering from want of 

 nourishment, Dr. Smith supplied potash, phosphoric acid, lime, nitrogen, etc., 

 in the form of guano, dried blood, superphosphates, muriate of potash, kainit, 

 kieserite, dissolved bone-black, dissolved bone ash, nitrate of potash, nitrate of 

 soda, sulphate of ammonia, Canadian hardwood ashes, lime, tobacco dust, and 

 barnyard manure. Also to learn whether healthy trees could be so strengthened 

 that they would be able to resist the yellows if these fertilizers were applied to 

 them also. Fifteen orchards were included in these experiments, containing 

 over 16,000 trees, in the heart of the great Delaware and Maryland peach region. 

 Here, before the advent of the peach yellows, the peach trees lived from twenty 

 to forty years, and still attain to such age in a productive condition in those 

 sections where the yellows have not yet appeared. 



To determine whether, in diseased branches, excess of lime and deficiency 

 of potash and of phosphoric acid were constant conditions, careful chemical 

 analyses of such twigs were made by Dr Eastwood, Professor of Chemistry in 

 Georgetown College, Kentucky. In the case of branches sent from an orchard 

 near Dover, Delaware, he found in the healthy branches 15.53 per cent, of 

 potash, and 10.63 P er cent, of phosphoric acid, and in those affected with 

 yellows, 20.16 per cent, of potash and 12 63 per cent, of phosphoric acid. In 

 branches from an orchard at Magnolia, Delaware, the healthy gave 28.26 per 

 cent, of potash, and 10.45 P er cent °f phosphoric acid; those showing yellows, 

 32.51 per cent, of potash, and 9 29 of phosphoric acid. Branches froui an 

 orchard at Still Pond, Maryland, from healthy trees gave 30.18 per cent, of 



