PEOF. ERWIj^ SMITH'S PRELTMIISlARY REPORT 



OJS" PEAOH YELLOWS. 



This important horticultural document was issued in March, 1889, as Bul- 

 letin No. 9 of the United States Department of Agriculture, botanical divis- 

 ion. It had been expected for several months by horticulturists throughout 

 the country, and the demand for it was so general that the edition was quickly 

 exhausted — none was obtainable a few weeks after the first was issued. On 

 this account, and because peach culture is so considerable a factor in Michi- 

 gan pomology, it is deemed expedient to quite fully reproduce here the results 

 of Prof. Smith's researches, which form the best, if not the only, investiga- 

 tion and review of the subject yet produced. 



HISTORY AND DISTRIBUTION. 



Yellows is a disease of peaches, nectarines, almonds and apricots. It does 

 not occur in plums. I have myself seen it only in peaches, nectarines and 

 apricots, but the evidence that it also occurs occasionally in almonds is reason- 

 ably satisfactory. In apricots it is rare. The two trees which I have seen 

 were covered with the characteristic shoots but bore no fruit, so I cannot tell 

 how it might affect the latter. Noyes Darling also saw it in apricots, but 

 did not see the diseased fruit. 



The peach is most inclined to this disease, and for that reason I shall con- 

 fine my study to the effects on that tree. 



The name yellows was first applied to this disease, near Philadelphia, at 

 the beginning of the century, as we shall see later. The term has passed into 

 universal acceptance, but the origin of the malady is unknown. It was much 

 written upon in the early part of the century and has engaged the attention 

 of horticultural writers from that time to this. Nevertheless, its nature is 

 but little better understood to-day than it was fifty years ago. 



GEOQEAPHICAL DISTRIBUTION". 



Peach yellows appears to be confined exclusively to to the eastern United 

 States. I can find no reference to its occurrence in California or anywhere 

 west of the Rocky mountains, and it is doubtful if it occurs to any extent west 

 of the Mississippi river. At least the peach growers of Kansas, Missouri and 

 Texas affirm that it does not occur in their orchards. To determine positively, 

 however, that the orchards in these states are exempt would require a careful 



