ORNAMENTAL AND SHADE TREES 



1117 



especially in winter. Can you suggest the proper way to 

 trim these trees and still prevent rank growth of new 

 shoots ? 



Will you tell me why the trimming should be done 

 before the leaves fall? Is not the winter just as good a 

 time as early fall? D. P., Boise, Idaho. 



A. Box elder, locust and poplar trees lend themselves 

 to severe and frequent cutting. They grow so fast that 

 unless they are cut in they become either too tall or too 

 thin and are liable to break in wind storms. The cutting, 

 however, need not be done too frequently. All that is 

 Necessary is to control the crowns whenever they become 

 too tall or sparse looking. This will prevent their appear- 

 ing so stubby. Maple crowns should be kept compact by 

 an occasional light clipping from the tips inward, but they 

 should not be headed in, as you describe, unless they are 

 very old and failing. Silver (soft) maples will require 

 more frequent cutting than the other maples. The sugar 

 maple should be cut but very little, if any. We suggested 

 trimming ornamental trees in the Fall as a general policy 

 because in that season the dead branches can be dis- 

 tinguished from the live ones with more certainty and 

 ease and the climbing can be done with greater safety 

 and ease than in winter when the branches are brittle 

 and slippery. 



Q. I would appreciate it if you could give me some 

 information relative to the most desirable sprays for 

 various tree diseases or insect attacks, or refer me to 

 some article or book on the same. I also would like to 

 have your opinion as to the most desirable spacing for 

 street trees, such as elm, hard maple, etc. 



W. W. M., Chicago, III. 



A. It would hardly be practical to give you a complete 

 list of all the spraying materials and the proportions in 

 which they are to be used. This would vary so much 

 with the character of the insect and the time of appli- 

 cation that in each case you should have specific advice 

 from your local State Entomologist or from the Depart- 

 ment of Agriculture. There are a number of good pub- 

 lications relating to the particular materials and their 

 applications, issued by the United States Department of 

 Agriculture, by the New York State Department of Agri- 

 culture, and by the various experiment stations through- 

 out the States. "Studies on Trees," published by John 

 Wiley & Sons, New York, as well as "Shade Trees in 

 Towns and Cities," issued by the same publisher, are 

 suitable books for you to read. "The Care of Trees in 

 Lawn, Street and Park" is one of the best books you can 

 read. 



As to spacing trees on city streets, I would suggest 

 that for most species a space of 30 to 35 feet should be 

 allowed, and for the American Elm 60 feet is appropriate. 



Q. Last June the greater number of the trees on my 

 farm in New York seemed to be suffering from the 

 attacks of one sort of insect, pest or another. The elms 

 and young hickories seemed most affected. The oaks and 

 maples showed leaves badly chewed. 



G. R., White Plains, N. Y. 



A. It is difficult to determine the exact cause without 

 an examination of the insect or at least the affected Ifeaf 

 or twig. If the character of the injury is eating of the 

 leaf, then the tree will have to be sprayed with arsenate 

 of lead. The exact time for spraying will depend on the 

 kind of insect. If the injury is due to a boring or suck- 

 ing insect, the treatment will again be different and in 

 each case will depend on the exact nature of the par- 

 ticular insect in question. 



Q. Can you tell me about an efficient insecticide for 

 fruit trees? G. A. F., Richmond, Va. 



A. As a result of extensive tests during 1913, 1913, 

 and 1914 with different insecticides, the entomologists of 

 the United States Department of Agriculture have found 

 that calcium arsenate, a new insecticide, gives very prom- 

 ising results in the control of certain insects that do dam- 

 age by chewing on fruit trees. Among the chewing 

 insects against which the arsenate of calcium proved 

 efifective, in laboratory and field tests conducted at Benton 

 Harbor, Mich., are the codling moth, the fall webworm, 

 the tent caterpillar, and the tussock moth. 



In these tests the effects of arsenate of calcium, both 

 alone and combined with lime-sulphur solution, were 

 tested in comparison with arsenate of lead alone and in 

 combination with lime-sulphur. The arsenate of calcium, 

 as was the arsenate of lead, was used at the rate of 2 

 pounds to each 30 gallons of water. In all the experi- 

 ments the arsenate of calcium gave very satisfactory re- 

 sults in killing the larvae without burning the foliage. 

 In a number of cases its killing action was somewhat 

 s'ower than, but compared favorably with, the arsenate of 

 lead. Since it can be produced more cheaply than the lead 

 arsenate, it would appear to have distinct value, although 

 it has not been sufficiently tested to permit recommending 

 it unreservedly for general use. Where arsenate of 

 calcium was combined with lime-sulphur it was, as a 

 rule, even more effective as a poisoning agent than when 

 used alone and did not lessen the value of the latter as a 

 fungicide. When these compounds are combined, the 

 amount of foliage consumed by the larvae is less than 

 where the arsenate of calcium is used alone. 



Q. Please mention a few shrubs and trees most suita- 

 ble for underplanting in a bit of natural woodland in the 

 vicinity of New York City. L. P. R., Nezv York City. 



A. You should resort to native shrubs and trees of the 

 following species : 



Shrubs Spice bush, viburnum acerifolium, juneberry, 

 red-berried elder, viburnum pruni folium. New Jersey tea, 

 viburnum cassinoides, sweet pepperbush, mountain laurel, 

 rhododendron. 



Trees Hemlock, beech, dogwood. 



Q. What is the best way to gather the eggs of the 

 Tussock moth caterpillar? P. C. C, Waierbiiry, Conn. 



A. Collect them by hand picking wherever possible. 

 Where the trunks of the trees are heavily covered with 

 them and where there are many trees in question, place 



