408 STATE HORTICULTURAL SOCIETY. 



objected that, being slow to diffuse in the soil, time enough was not allowed 

 for their action; but no such argument can be brought forward to explain 

 the results of a period of years. Neither can it be advanced that the 

 substances have washed away. There has been no surface washing, and it 

 is well known that the soil holds on to potash and phosphoric acid 

 with great tenacity. The disease has increased for three years, pari pass n 

 with the increase of fertility in the soil. 



Not to weary you further with results so purely negative, and in one 

 sense so unsatisfactory, I must conclude this paper, as I did my former 

 one, with expression of the belief that the Goessman-Penhallow method 

 of treatment was founded on an error, and that we are to look for the 

 cause of peach yellows and the means of prevention in an entirely differ- 

 ent direction. Concerning the now well-established contagious nature of 

 this disease, see Bulletin No. 1*, recently published by the division of 

 vegetable pathology of the U. S. department of agriculture. 



DISCUSSION. 



Dr. Johnson: I should like to ask the Professor one question or two. 

 Has the Professor ever examined the roots of the diseased trees ? Is not a 

 healthy root of a peach tree the color of yellowish white, and of a tree that 

 is diseased of redish yellow ? 



Dr. Smith: I have never found any constancy in that matter. 



Mr. Caky : The question I wish to ask is this : I do not think in Geor- 

 gia we have yellows. We have a disease, but it is not yellows. I want to 

 ask this question: Does yellows kill the tree which it attacks the first 

 year ? 



Dr. Smith: It is not likely to. I have sometimes known a tree to be 

 killed in one year, more in two, but a majority not under four, five, or six 

 years. 



Mr. Cary: Will they bear perfectly for the second or third year ? 



Dr. Smith: Sometimes part of the tree will bear perfect fruit the sec- 

 ond or even the third year. It depends on how seriously it is attacked at 

 the start. 



Mr. Gary: We have in Georgia a disease called "rosette" — it assumes 

 that form, but Mr. Berckmans and Colonel Redding both say it is not 

 yellows. It is fatal and kills out the trees, but I don't know what it is. 



Dr. Smith: It is dangerous, seriously so; quite as much as peach 

 yellows, but I think different from it. I have studied it carefully for two 

 years. 



Mr. Garfield: I should like to inquire whether the gentleman has 

 found peach yellows in New Jersey and Massachusetts. 



Dr. Smith: I have been in New Jersey and Massachusetts, and have 

 seen yellows in both places, and I believe yellows occurs from one end to 

 the other of both states. I do not think there is a peach-growing county 

 in either state wholly exempt; and I have seen a great many cases which I 

 consider to be identical with the Michigan yellows. 



Mr. Engle: Will the peach take yellows when worked on the plum ? 



Dr. Smith: I began several series of that kind of experiment this year, 

 budding on plums and cherries, to determine whether the disease can be 

 transmitted to these plants It is perhaps too soon to expect results. One 



*Dr. Smith'p " Additional Evidence." See page 165, this volume. 



