PEACH YELLOWS. 293 



served. The question is, Were they the cause of the diseased top, or was 

 the tree suffering from two distinct evils? In orchard No. 11 of this report 

 (same farm) all the replants of J 887 showed the same diseased appearance as 

 this tree, and iu four out of five trees which were examined I found root 

 aphides in considerable numbers, and had reason to think that they had been 

 present on the roots of the other tree. These insects were also found upon 

 the roots of older trees in the same orchard. 



In an orchard owned by John Stokes, Still Pond, Md., and containing trees 

 diseased by yellows, I also saw two resets of 1887, with tops of identical 

 appearance. On the roots of one I found aphides, and on the roots of the 

 other some indications of their former presence. 



On the other hand, on the farm of Henry Krusen, Still Pond, Md , out of 

 two thousand trees set iu 1887, I saw about thirty that had the same appear- 

 ance. Eight of the worst ones were examined very carefully for aphides and 

 the yellow ants, but neither were found. Two of the trees had been injured 

 by borers, but the rest were free from bark injury. 



The only difference which I could detect between the wiry, branched, de- 

 pauperate growth on these trees and that found on robust older trees, bearing 

 premature peaches, was iu the lesser tendency toward autumn growth, and I 

 ■cannot say that even this is a constant difference. When placed side by side 

 with growths from older trees, it was not always easy to distinguish one from 

 the other. I am inclined to believe that where aphides were on the roots the 

 unfortunate trees were suffering from two distinct evils; but some additional 

 observations oug]it to be made. 



INJURIES BY FUNGI. 



The peach, like other plants, is subject to the attacks of parasitic fungi ; 

 but whether yellows is caused by a fungus or a bacterium remains to be deter- 

 mined. It certainly does not arise from any easily distinguishable cause of 

 ibis kind. 



In the regions affected by peach yellows, I have observed the following 

 species of fungi on the parts above ground : 



■ Taphrina deformans, TuL, on leaves and young shoots, producing the dis- 

 tortion and enlargement known as "curl;" Sphaerotheca panosa, Lev., a 

 white felt-like mildew on leaves and young shoots, causing atrophy and death ; 

 J*ticcinia Primi-spinosce, P., producing rust-spots and causing the premature 

 fall of the leaves; Oidium fructigenum, Kze. and Schw., causing *'rot" in the 

 fruit and "blight" in the twigs; CladospoHum carpophyllum, v. Thiim., a 

 surface-growing fungus on leaves and fruit, producing roundish black spots, 

 which are especially frequent on Smock and other late peaches ; Cercospora 

 PersiccB, Sacc, producing faint frosted patches on the under surface of the 

 leaves, and indistinct yellow spots above; Cercospora (?), producing numerous 

 leaf-spots having a dead center and a more or less brightly colored rim of 

 red or purple ; Capnodium elofigatwn, B. and Desm., an imperfect form, 

 probably referable to this species, producing black patches on the epidermis, 

 and occurring also in the gum ; Polyporus versicolor, Fr., on trunk and limbs, 

 principally or wholly on dead or dying wood, and not restricted to trees suf- 

 fering from yellows or even to the peach. 



Some of these fungi are genuine parasites ; others are what De Bary styles 

 faculative parasites ; and others are pure saprophytes. None of them stand 



