DISEASES OF CULTIVATED PLANTS. 419 
Gum-Flow. The gum-flow diseases of the peach are frequent but have, as 
yet, been imperfectly studied in our state. Wehave no distinct gummosis, al- 
though in some varieties of peaches it would seem this is a weakness or a form 
of injury due to climate followed by gum exudations. Bark borer injuries pro- 
duce a well-marked gum-flow. 
June Drop is often named by peach growers as a specific trouble. It consists 
in the dropping of the young peaches during the month of June, though drop- 
ping sometimes comes.earlier. The cause seems to be physiological and need 
not be feared where the trees have been prevented from overbearing, or protected 
from the effects of drought by thorough cultivation the previous season. 
Little Peach is a disease much discussed.in Michigan and is quite serious 
in the fact that the peaches on diseased trees never come to proper maturity or 
develop marketable character. Dr. Smith has found that the root hairs on many 
such trees are not healthy and thus it appears that some specific trouble is 
located there. 
Leaf-Curl (Exoascus deformans B). The leaf-curl fungus is at times one of 
the serious pests of the peach grower. However, destructive leaf-curl does not 
occur every year. The curl fungus survives as mycelium in the buds from year 
to year. It is therefore present each season, though possibly in varying amount. 
Fig. 70. Leaves of peach attacked by leaf-curl. The attack of the fungus causes rapid cell mul- 
tiplication and results in the distorted shapes. From a photograph. 
