92 QUINCE CULTURE. 
parts, as shown in the cut. The destruction of affected 
leaves is recommended, especially as many of them are 
also affected with both of these fungi together. 
5. LeaF Mitpew (Podosphera tridactyla, Wall).— 
This disease consists of a parasitic white mildew spread- 
ing interlacing filaments over both surfaces of the leaves, 
but developed most perfectly on the upper side. , The 
disease appears in June, producing a multitude of color- 
less spores, which spread the fungus rapidly to other 
leaves and trees. Late in July it produces its fruit 
Fig. 65.—LEAVES AFFECTED BY THE HENDERSONIA CYDONIA, 
as so many dust-like dots of regular form and size. 
These round, dust-like specks are the sacks which 
contain the resting spores, which withstand the rigors of 
winter, and reproduce the leaf mildew the next year. It 
is most thrifty on the leaves of a vigorous tree; but, 
with the favor of shade, may thrive on a weakly tree. It 
is also found on the leaves of apple trees, and proves very 
injurious to cherry leaves, often causing them to fall 
prematurely. Sulphur dusted on the leaves when they 
are wet is recommended as a remedy. 
