26 



should be pruned very sparingly. Dead or dying limbs 

 must be lemoved, of course, and occasionally a limb should be taken off 

 to prevent a crown from becoming one-sided. Lower limbs should not 

 be removed from small trees as a general rule, as this spoils the sym- 

 metry of the tree and makes them top heavy. This is true of the coni- 

 fers, but the broadleaf evergreens, like live oak and magnolias, may be 

 handled like the deciduous trees. 



It is highly desirable to use fertilizer to maintain the food materials 

 in the soil. Too often trees are starved to death. Commercial fer- 

 tilizer should be applied rather sparingly since it is easy to get too much 

 and thus injure instead of benefit the tree. 



TREE TROUBLES AND REMEDIES 



City trees are subject to many injuries, diseases and insect attacks 

 due to their unnatural surroundings. They must be carefully watched 

 and kept in as thrifty a condition as possible so that they may be re- 

 sistant to a great extent or able to recover quickly in case they do suffer 

 some reverse. 



INSECTS 



Insects are the bane of a tree's existence in the forest and even more 

 so in the city where natural parasites are lacking and birds are rela- 

 tively scarce. The insects which attack trees may be classed under three 

 general heads according to their various feeding habits. These three 

 classes are known as sucking insects, borers, and defoliators. Each class 

 must be combated in a different manner. 



The sucking insects include scales, mealy bugs, and plant lice. They 

 feed on plant juices through sucking mouth-parts. Scales are minute 

 hard-bodied flat or slightly convex insects which fasten themselves closely 

 to the trunk, twigs, or leaves, and usually are unable to move around 

 after they assume the adult form. The younger stages of scale insects 

 may fly and migrate, however. . The oyster shell scale is a well known 

 example of this class of insects. Another is the cottony maple scale, 

 which is much larger than most of the scales and which secretes a mass 

 of white waxy threads. Mealy-bugs are soft-bodied small insects which 

 are characterized by the waxy, cotton-like covering which they exude. 

 Citrus mealy bugs attack many orange trees in this state. Plant lice 

 are soft-bodied insects, too well known to require further description. 

 They feed only on young tender shoots and are often found injuring 

 willow and poplar. 



Scales. Since the control methods are essentially the same for all 

 scales they will be considered as a group. They are best combated in 

 winter, since stronger sprays may be used and more satisfactory results 

 obtained. 



Lime-sulphur is the most useful spray against scale insects, and, fur- 

 thermore, it has some value as a fungicide. Lime-sulphur may be se- 

 cured ready made, needing only dilution to be ready for use. Usually 

 10 per cent stock solution to 90 per cent water will give satisfactory 

 results. Lime-sulphur may be made at home if desired but the com- 

 mercial product is preferable. 



