112 Principles of Plant Culture. 
the brown spots so often observed upon the leaves of indoor 
plants that have been sprinkled in bright sunlight. Some- 
times, but rarely, this trouble occurs in the open air. 
186. Sun-scald is a term 
applied to an affection of the 
trunk and larger branches of 
certain not-fully-hardy trees, 
usually upon the south or 
southwest side, in which the 
bark and cambium layer are 
more or less injured (Fig. 57). 
In severe cases, the cambium 
is totally destroyed, and the 
loosened bark splits longitu- 
dinally or becomes detached. 
The effect is apparently the 
same as when a tree is exposed 
to the heat of a fire. Sun-scald 
is most common in young trees 
and appears to be due, in some 
cases, to the superheating of 
the cambium in summer,—in 
others to a return of severe 
freezing weather after a period 
sufficiently warm to excite the 
cambium cells to activity. A 
preventive is to shade the trunk 
and larger branches by inclosing 
: Se Fic. 57. Showing effects of sun-scaid 
them with straw or similar ma- on trunk of silver maple tree, Acer 
terial, or with a lath screen @/07P™m. Madison, Wis, 
(Fig. 58). 
