THE MONTHLY BULLETIN. 383 



missioner of the county, who finds it necessary to require all the trees 

 on the city lots to be cleaned at proper intervals. This is for the pro- 

 tection of the adjoining orchards, which dovetail in so completely with 

 the outlying sections of the city that no line of demarcation can be 

 drawn for the purpose of leaving out any portion of the cit5\ It fol- 

 lows that when city lots are cleaned street trees in the same section 

 must also be cleaned. Accordingly the same system of notifying owners 

 to clean condemned trees is applied to street trees and the park super- 

 intendent is notified to spray infested shade trees. This is done with 

 regularity and all street trees are sprayed by the city's own spray 

 outfit. 



Black Acacias, etc., infested with ivy scale {Aspidiotus kederce) are 

 sprayed early in the season — March or April if possible — with a 3^ 

 per cent mechanical mixture of distillate and water. The distillate 

 used is common stove distillate of about 30 degrees test. It is intended 

 as soon as these trees are treated to spray the camphors in the 

 same way for red scale {Chrysomphalus aurantii), with a 5 per cent 

 mixture of distillate, this spraying to be repeated, in bad cases, in 

 three or four weeks. 



After this work is done the Sterculias and Acacia florihunda are 

 sprayed with resin wash for the greedy scale (Aspidiotus camellice). 

 It is planned to have all these done by the first week in August or 

 thereabouts, if possible, when it is time to begin spraying the pepper 

 trees, etc., for black scale {Sassctia olece) as its eggs are mostly 

 hatched by that time. A 5 per cent mixture of distillate is used for 

 black scale also. One spraying is not usually enough, as there will 

 always be some black scale eggs that have not hatched, and a second 

 spraying is necessary and should follow in six or eight weeks after the 

 first spraying. Spraying pepper trees with a 5 per cent mechanical 

 mixture of distillate is perfectly safe in any month, if care is exercised 

 not to spray in the middle of the day, when the thermometer shows 

 excessively high temperature, or when a hot north wind is blowing. 

 Later in the season, when the weather is cooler and the scale insects 

 larger, it is better to increase the proportion of distillate to 6 per cent 

 or even 7 per cent. 



Should the trees be sprayed when it is too hot, or if spraying is 

 followed immediately by a hot north wind, the only harm likely to result 

 will be the sudden dropping of old leaves in the ensuing two or three 

 days. These would very naturally be shed in a few weeks, and the 

 spray simply hastens the dropping. No harm results, as the new growth 

 of foliage quickly folloAVS. 



Spraying, hoAvever, is not the only method used to reduce the black 

 scale. The park superintendent has inaugurated intelligent, systematic 

 pruning by a crew of trained tree trimmers, under the direction of a 

 tree warden. This materially reduces the infestation and makes spray- 

 ing more easily accomplished, more efficient and less expensive. 



The pepper trees are so trimmed that traffic on the sidewalk is not 

 interfered with by low hanging branches or drooping twigs ; also the 

 branching framework of the tree is so raised that street lights will not 

 be obstructed. Then the interior branches and twigs are removed and 

 the tree is thinned out from the underside and the inside, leaving a 

 canopy-like shell of foliage which preserves the natural contour of the 



