Reprint from American Rose Annual 
Black-Spot Control Substantiated 
By EDWIN M. ROSENBLUTH, Wallingford, Pa. 
Editor’s Note. —In the following brief article, Mr. Rosenbluth tells an 
amazing story, and he backs it up with convincing proof. We have omitted 
from the article the list of interested rosarians who visited his garden during 
the course of the test, some of whom have reported substantially the same thing 
to this office. We also ran a test of these materials at Breeze Hill last summer, 
following closely the directions given by Mr. Rosenbluth in last year’s article. 
Never before has Breeze Hill been so free from black-spot and mildew infection. 
The one outstanding thing which we have learned from the past two years’ 
study of Mr. Rosenbluth’s methods is that thoroughness counts more than any¬ 
thing else. As Mr. Rosenbluth makes plain, it is essential to hit every portion of 
the plant with the spray, particularly the undersurfaces of the leaves. Spraying 
cannot be hurried—it must be a slow and painstaking job. We are so sure of 
this fact that we believe it is more important than the concentrated strength 
of the material used. 
S HORTLY after the publication of the article “Black-Spot 
Can Be Controlled” in the American Rose Annual for 1932, 
we received a letter from Dr. L. M. Massey, Plant Pathol¬ 
ogist of Cornell University, who appeared to be somewhat skep¬ 
tical of the results which we obtained. He asked us whether we 
would be willing to leave a section of the garden unsprayed in 
1932, to determine whether we had black-spot infection in the 
neighborhood, since none had appeared in the garden. 
While we knew that there was plenty of black-spot infection 
in the neighborhood, we were confident in the efficacy of our 
treatment and gladly complied with the eminent doctor’s 
request to see whether black-spot would develop. 
Thirty-one plants in the eastern end of bed No. 6 were 
selected for the test. These were left entirely unsprayed. The 
western end of the bed was given our usual treatment along 
with the rest of the garden of 1200 or more plants. 
Almost as soon as the plants in the untreated plot put out 
their new foliage, mildew appeared and aphides were much in 
evidence, soon followed by black-spot. The infection became 
worse from week to week, and between June 12 and 22 practi¬ 
cally defoliated the plants. Rose-slugs ate holes in the remaining 
foliage. 
On July 2, Mr. Bruce Parsons, Dr. Massey’s assistant, came 
to the garden unannounced and saw the sad condition of the 
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