22 



PEACHES AAB YELLOWS IN THE CHESAPEAKE COUNTRY. 



Into this distress has come one of the most patient and 

 careful investigators who has ever studied diseases of 

 plants. Erwin F. Smith, the agent of the Department 

 of Agriculture, has been working here and in Georgia, 

 Michigan and Kansas for three or four years in a quiet, 

 but I am convinced in a most efficient way. The 

 amount of his work is enormous, and I think that he 

 has settled many of the disputed points. To be sure, he 

 has not discovered the cause of the disease, but he is con- 

 stantly eliminating probable causes. But the ultimate 

 cause is really less important in a practical way than 

 most people imagine. It is by no means probable that 

 we shall be able to cure the yellows when the cause is 

 known ; but we shall, perhaps, know better how to 



But there is not one material which has had the least 

 effect upon the yellows, either in curing it or in keeping 

 it away. And these tests have been made upon a scale 

 and with an exactness never before approached. I 

 visited the larger part of these test orchards and exam- 

 ined them critically, and I was totally unable to detect 

 any modification of the disease which could be attributed 

 to fertilizing. Continuous cropping of poor soils, wilh 

 no fertilizers, has failed to augment the disease. I am 

 satisfied that the soil exhaustion and special fertilizer 

 theories are irrevocably overthrown. 



This is but a sample of the work under way. A 

 series of tests upon cutting off the first diseased twig as 

 soon as it appears, have shown that the tree is even then 



Fig. 



A Six-year-old Chesapeake Peach Orchard. 



control it. Dr. Smith's field experiments with fertil- 

 izers number loo, and cover 40 acres of orchard in Dela- 

 ware and Maryland ; and 40 acres more are reserved 

 as checks. These experiments cover the whole range of 

 special and general fertilizers, in all combinations. 

 Potassic, phosphoric, nitrogenous, and all manner of 

 compound fertilizers have been employed. The experi- 

 ments are now two seasons old, and they have been 

 made upon sick orchards to cure them and upon well 

 orchards to protect them. All the special compounds 

 and nostrums which have ever been recommended are 

 used. Many of these fertilizers have produced most 

 marked effects upon the trees. The nitrogenous com- 

 pounds often add almost wonderful vigor and color. 



constitutionally diseased, for such trees invariably die 

 In only one or two cases has it been found that the dis- 

 ease does not again appear until the second year. It 

 seems as if the whole tree is diseased before any symp- 

 toms are seen. Experiments upon the use of various 

 stocks are in progress. I saw one peach orchard grown 

 upon plum stocks in order to ascertain if the plum 

 would afford immunity from the disease. This is a 

 young orchard and results cannot be announced yet. 

 Various budding and inoculation experiments are in pro- 

 gress, from Georgia to Michigan, 



One of our best horticultural writers has said that 

 tobacco applied to the soil will cure the yellows. The 

 investigation of this point has resulted in a most im- 



