253 
PLUM LEAF-BLIGHT ( Cylindrosporiim padi Karsten.) 
The plum leaf-blight in western New York, aside from giving much 
trouble to nurserymen, does very great damage to many varieties of 
bearing trees, defoliating them in August and September. This disease 
is considered by the plum-growers in the vicinity of Geneva as their 
most persistent enemy. A large orchard belonging to E. Smith & Sons, 
2 miles northwest of the city, was, they informed me, winter-killed 
about thirty years ago because of defoliation the summer previous. It 
is a common opinion among orchardists that leaf-blight, through its 
retarding effect upon the maturation of the wood, renders the trees 
incapable of withstanding the changes in temperature of a trying win¬ 
ter. Whatever the explanation of this fact may be, it seems self-evi¬ 
dent that a tree which drops its leaves before the normal season suf¬ 
fers verv material loss. 
Of nursery stocks, the native-grown seedlings suffer the most from 
this disease, often losing all their leaves by the middle of August. My¬ 
robolan and Marianna stocks are not to any extent subject the first 
season. In entire contradistinction to the immunity exhibited by 
pear “buds” which resist to a remarkable degree pear leaf-blight, the 
budded plum stocks are particularly susceptible to plum leaf-blight. 
Apparently the same conditions of rapid growth which afford immunity 
in the one case tend to susceptibility in the other. The two instances 
offer a fertile held for inquiry. 
The experiments on this disease were made with Bordeaux mixture 
and ammoniacal solution upon two rows of stocks, one of Marianna, 
containing 501 stocks, and the other of Myrobolan, containing 471 
stocks. As described previously* the results of the first season’s ex¬ 
periment were entirely negative, as the disease failed to appear. 
On October 9 the three varieties, Early Prolific (Early Rivers), Pur¬ 
ple Egg (Hudson River Purple Egg), and Italian Prune (Fellenburg), 
were budded upon both rows of stocks as set forth subsequently, p. 258. 
Numerous stocks were left unbudded to test the effect of the fungicides 
and the end of each row was left untreated. 
The rows were treated in 1892 with Bordeaux and ammoniacal solu¬ 
tion, the formulae of which are described on p. 2G2. One-half the 
treated stocks received 5 sprayings and the other G, at the dates given 
on p. 243. In all respects the two rows were treated alike. 
MYROBOLAN STOCKS. 
1802 .—The disease made its first appearance in June upon the un¬ 
budded stocks which were carried over from 1891, and strangely 
enough only upon the treated portions. This dropping of the treated 
Myrobolan foliage was confined to the leaves situated on the larger 
* Bull. No. 3 Div. Veg. Path., p. 58. 
1G48G—No. 3-5 
