Plants as Affected hi/ Seat. 



IVi 



heat that is fatal to the foliage beneath them. This may 

 explain the brown spots so often observed upon the leaves 



of indoor plants that have been 

 sprinkled in bright sunlight. 

 Sometimes, but rarely, this 

 trouble occurs in the open air. 

 186. Sun-scald is the term ap- 

 plied to an affection of the 

 trunk and larger branches of 

 certain not quite hardy trees, 

 usually upon tlie south or south- 

 west side, in which the bark 

 and cambium layer (69) are 

 more or less injured (Pig. 58). 

 In severe cases, the cambium 

 is totally destroyed, and the 

 loosened bark splits longitudin- 

 ally 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 suf- 

 ficiently warm to excite the 

 Fig. 58. Showing effects of sun- cambium cells to acti^'it^■. A 



scald on trunk and branches of 



silver maple tree, Acer dwsycar- preventive iS to ShadC the 



^"""- trunk and larger branches by 



inclosing them with straw or similar material, or with a 

 lath screen (Fig. 59). 



