PEACH DISEASES 301 
an enlargement at the point of injury. Evidences of the 
disease are noticeable in late winter or early spring months. 
Affected twigs are at first purplish, but later scarlet, and leathery. 
Still later the bark becomes drab-colored, loose and wrinkled. 
Finally black pustules of the pathogene appear under the bark 
in these grayish areas. These fruiting bodies break through 
the bark and become covered with a silvery-white coat, thus 
dotting the whole diseased portion in a characteristic manner. 
This condition is often spoken of as silver-twig. Twigs and 
water sprouts are killed back in mid-winter or later. This 
killing occurs repeatedly until finally the affected tree is given 
a ragged appearance. During the growing season an affected 
limb or twig may be girdled, in consequence of which the foliage 
assumes a yellowish aspect, then suddenly wilts and dies. 
Cause. 
While the causal factor is designated as the fungus Valsa 
leucostoma var. cincta, the general opinion prevails that other 
factors such as frost, unfavorable soil, lack of cultivation and 
other neglect play an important réle in the production of the 
die-back disease. Indeed, some prominent authorities hold 
that the prime cause is the action of low temperatures. The 
fungus may in any case be regarded as an exciting cause 
at least, and in its absence the other above-named factors 
would doubtless exhibit less influence in bringing about the 
‘trouble. The pathogene characteristically attacks trees in 
a weakened condition, like those injured by frost and fire. 
And this is a real source of danger, inasmuch as such trees 
when taken at this disadvantage suffer injury far in excess of 
that induced by frost alone. Furthermore the semi-parasitic 
nature of the fungus allows it to live indefinitely about the 
orchard on dead limbs, ready to attack any trees that are in 
poor condition. A warm spell in the spring followed by a 
freeze renders the tissue of the peach-limbs favorable to the 
growth of the fungus. 
