306 



SOILS AND PLANT LIFE 



A blanket of smoke from burning litter will prevent 

 the escape of heat from the soil and in this way will often 

 prevent frost. Among the interesting sights to be seen 

 at times in some commercial orchards are the long lines of 

 pots of burning oil or coal, which make a dense smoke and 



CouTte^^y Iowa .Slate College. 

 Fig. 139. — Keeping Jack Frost away. 



at the same time generate heat enough to keep the tem- 

 perature of the orchard above the danger point. 



Sunscald. — Undue exposure of the trunks of young 

 trees to heat and cold may destroy a part of the bark, 

 producing what is known as sunscald. Binding a layer 

 of cornstalks, wood veneer or burlap about the trunks 

 ^\'ill protect them in the winter and early spring. These 



