332 MANUAL OF FRUIT DISEASES 
ScaB 
Caused by Venturia Pyrina Aderh. 
Although apple- and pear-scab are very similar in all respects, 
they are not the same disease. The general opinion prevails 
among growers that because pear-scab looks like apple-scab, 
and because the two diseases bear similar names and are con- 
trolled in approximately the same way, the one is identical 
with the other. But the causal fungus in the one case is specifi- 
cally different from that in the other, and therefore a scabby 
pear-tree is in no way dangerous to an apple tree and vice versa. 
Pear-scab is perhaps as well known to growers of this fruit 
as any other disease except fire-blight. It has a wide range, 
but is controlled with less difficulty than fire-blight, and con- 
sequently is not nearly so greatly feared. On the other hand, 
it does considerable damage. For example, it is estimated 
that pear-growers in the State of Ohio lost in 1905 at least 
$50,000 through this disease alone. In practically all regions 
where it occurs it is second to fire-blight in importance. In 
California losses are put at 25 to 100 per cent in unsprayed 
orchards. In all carefully sprayed orchards the losses are 
much less, and often not appreciable. Damage is wrought in 
nurseries as well as orchards. 
The quality of the fruit, rather than the quantity, is affected. 
The taste is not altered noticeably, but the appearance and keep- 
ing qualities, as well as canning and drying qualities, are con- 
siderably impaired. Affected fruit sometimes falls and is then 
worthless. When blossom-pedicels are affected, a loss of the 
set of fruit results. This happens frequently. 
~ Not all varieties of pears suffer alike. Scab is notably com- 
mon on the Flemish Beauty, Winter Nelis and Easter Beurré. 
The Duchess, Seckel and Summer Doyenne are among the 
other susceptible varieties. Many others are at times scabby 
but not so frequently nor to such a marked extent as in the case 
