188 MANUAL OF FRUIT DISEASES 
WitcHEs’-BRooMm 
Caused by Exoascus Cerasi (Fckl.) Sadeb. 
Witches’-broom is a peculiar type of gall in which there is 
an over-production of whole organs, resulting i in a broom, or 
nest-like habit of growth. This name is in general use in North 
America. In England, the disease is called thunder-bushes, 
bull-boughs, bull-wood and bull-branch. The Germans refer 
to it under the name Hexenbesen, while the French call it 
Balai du Sorciére. 
The disease is very common and destructive in Europe, where 
both sweet and sour cherries are affected. Although the 
English sweet cherry (Prunus avium) is commonly cultivated in 
eastern United States, the disease was not recorded until 1886, 
when it was reported from Germantown, Pennsylvania. About 
ten years later it was found in Long Island at scattering points. 
The witches’-broom disease of cherry is not a disease well- 
known to American cherry-growers. It occurs sparingly in 
New York, but is said to be common in Oregon. It has also 
been observed in a few other states, including Washington, 
Minnesota, Pennsylvania and New Jersey. The disease is 
of most interest perhaps because of the fact that the pathogene 
spreads so slowly, and on account of the peculiar effect on the 
cherry. Its history thus far in this country does not indicate 
that the disease should ever be feared by cherry-growers. 
Records show that the disease may affect in this country the 
following cherries: English sweet cherry (Prunus avium), 
sour cherry (Prunus Cerasus), wild black cherry (Prunus 
serotina), wild red cherry (Prunus pennsylvanica), choke-cherry 
(Prunus virginiana). Several varieties and species of plums 
are also affected. 
Symptoms. 
The twigs and leaves are susceptible to this disease. On the 
former it produces a very striking deformity, although not a 
