842 REPORT OF THE COMMISSIONER: OF AGRICULTURE. < 
become moreorlessirregular. The older spots vary from one-eighth ea 
@ to one-half an inch in diameter; frequently two or more spots may 
- run together, forming large irregular blotches. Although most fre-_ 
quent on the upper surface of the leaf the spots sometimes appear on 
the under side, and the fungus often extends to the leaf petioles and 
young twigs, covering these parts with its dark, olive-green, velvety 
growth. When examined closely with a hand lens the spots on the 
leaves are seen to be made up of irregular threads radiating in all 
directions from a common center. . 
On the fruit (Fig 1).—The development of the spots on the fruit 
is similar to that which takes place on the foliage. They start from 
a center of infection and usually preserve a more or lessrounded 
outline. As they increase in size the ruptured cuticle appearsasa 
light-colored ring around their borders, and frequently flakes of the 
cuticle adhering to their surfaces imparts to them a more or less 
grayish appearance. The greatest vigor of the fungus is towards 
the margins of the spots, the central portion sometimes dying, and 
the apple beneath, in its efforts to recover from the disease, forms a 
corky layer which appears as a roughened, russet-like surface. 
(c) EFFECTS AND LOSSES. 
Throtgh the action of the parasite on the leaves there is an une- 
qual development in the two surfaces, causing a greater or lessdis- 
tortion of these organs and, when badly affected, their power of | 
assimilation is destroyed. Its injury to the twigs or young shoots, ~ 
when these aré attacked, is often quite serious in its character. It 
is on the fruit, however, where it produces the dark olive-green or 
black spots so well known to every orchardist as ‘‘ Apple Scab,” that 
the fungus causes the greatest injury. At no period of its growth 
is the apple exempt from the attacks of this parasite, but the most 
damage is occasioned when the fruit is infested early in the season. | 
Sometimes, when the apples are no larger than peas, the fungus of 
the scab may be found upon them, not infrequently enveloping their 
entire surface, and practically checking all further development. — 
When less severely attacked the apples may continue to grow, even 
to maturity, but the result is knobby, misshapen fruit of inferior 
quality. If the attack is made towards the close of the season the 
fruit may attain its full proportions and quality of flavor, but the 
spots, disfiguring its surface,'render it unsightly and depreciate its 
market value. 
Under ordinary circumstances there are some varieties which 
escapé the scab, but in some seasons, however, it respects neither con- 
dition of soil, mode of culture, nor variety of fruit. : 
The varieties reported to be comparatively free from the disease 
arethe Russets, Ben Davis, Winesap, Willow Twig, Jonathan, Rawle’s 
Janet, Smith’s Cider, Maiden’s Blush,Grimes’ Golden, York Imperial, 
R. I. Greening, Sops of Wine, Duchess. 
Those especially subject toits attacks are White Winter Pearmain, 
Huntsman, Northern Spy, Early Harvest, Carolina Red June, Fa- 
meuse, Baldwin, Hass, etc. 3 
It must be said, however, that varieties notably free from disease 
in one section when grown in some other locality more or less re- 
mote may scab badly. . 
_. The Bellflower comes into the markets in Washington nearly free 
from scab some seasons, while in others it is very badly affected, and 
