NOTES ON PLUM CULTURE. 
31 
PLUM POCKETS. (Exoascus Pruni Feld.) 
This disease is quite common on the wild Prunus Amer¬ 
icana of the foothills, but no case of attack upon cultivated 
varieties has come to my notice. The effects produced by 
the growth of this fungus are perfectly characteristic. Not 
long after the fall of the blossoms the young plums begin to 
enlarge rapidly; they become spongy or bladdery, and may 
vary in size from one-half inch to an inch and a half in 
diameter. In color they are pale green or yellowish. By 
the middle of June they shrivel somewhat, becoming 
wrinkled, and finally drop. Sometimes only a portion of 
the fruits on a tree are effected and again no normal fruits 
can be found. The fungus sometimes attacks the leaves 
and young twigs, but more commonly the fruit only is 
effected. From observations on wild plums it appears that 
trees once infected continue to produce pockets each year, 
and it is doubtful if these trees can be cured; but spreading 
to other trees can be prevented by gathering and destroying 
the pockets before the spores are discharged. Where the 
disease attacks cultivated plums it seems to be quite local 
and does not spread rapidly. It is never epidemic and there 
seems to be little danger of serious injury from it. Plum 
pockets as they occur on the wild plum are illustrated in 
Fig. 2, Plate 4, which was photographed from a dry speci¬ 
men. 
A BLIGHT DISEASE. 
Late in the summer of 1897 twelve trees in the orchard 
"were attacked by a blight, the nature of which is obscure. 
The leaves began turning brown at the edges; this spread, 
involving the whole leaf surface and the trees died. Exam¬ 
ination failed to reveal the presence of fungi, and it seems 
most probable, from the appearance and development of 
the disease, that its cause must be sought in some bacterium. 
The disease, while possessing the same general nature as 
pear blight, is certainly distinct from it. The trees attacked 
were all old and in bearing. No young trees suffered, and 
there was no reappearance of the disease this season. 
VARIETIES. 
The following notes on varieties are based almost 
wholly upon observations made in the station orchard. 
