40 



MASS. EXPERIMENT STATION BULLETIN 226. 



In every test Scalecide has given very nearly perfect control of the 

 overwintering eggs, when applied as a dormant or delayed dormant spray 

 in the spring. One test made with this material applied in the fall gave 

 a degree of control considerably less than that from spring application. 



Against the overwintering egg masses of apple tent caterpillars, while 

 not yielding such striking results as noted above, Scalecide has caused a 

 vpry substantial reduction in hatch. In view of the increasing abundance 

 of this pest throughout Massachusetts during the past few years, this 

 beneficial effect of Scalecide is of considerable significance. 



A study of the effect of this spray upon the early spring infestation of 

 apple aphids has not been as comprehensive as might be desired, due to 

 the scarcity of material thus far available. Results to date have indicated 

 a very definite reduction in the numbers of plant lice, from a spring ap- 

 plication very nearly approximating the time of hatching of tiie eggs; i.e.. 

 the so-called "delayed dormant" period. Apiilication as a purely dormant 

 spray yielded \ery slight control of the subsequent hatch. 



Spring application of Scalecide on pears yielded a very material check 

 upon the infestation of pear psylla as based on the comparative number of 

 eggs deposited upon unsprayed and sprayed trees. In one season there 

 was found to be a reduction in infestation amounting to over 90 per cent 

 on trees sprayed with Scalecide as compared with unsprayed rows along- 

 side. The following season favorable weather conditions in early spring 

 allowed early activity on the part of the psylla, and some eggs had been 

 deposited before the spray was applied. Subsequent counts of eggs on 

 sprayed blocks indicated a control of better than 8.5 per cent. Fall appli- 

 cations did not yield anj^ striking control. 



Tests made during one spring, using Scalecide diluted 1 to 20 on a 

 small planting of ornamental spruce, against overwintering stages of the 

 spruce gall louse, resulted in very satisfactory control of the insect and no 

 injury to the trees. 



Tests with the oyster-shell scale yielded negative results. Except for 

 causing a possible slight delay in appearance of the newly-hatched young, 

 there was very slight effect noted following the sprays. The difference in 

 amount of hatch between unsprayed trees and those given the oil, if any 

 existed, was not enough to be measurable. 



In every instance the material was found to possess excellent physical 

 qualities. It "flowed" from the container without difficulty even when the 

 weather was cold, a feature which favorably impresses any grower who has 

 had experience with oils. In preparation for the spray, the material offered 

 no dift'iculty, mixed readily with the water, and required only moderate 

 agitation. It formed a very stable solution from which there was little 

 or no oil separation, even upon standing for a considerable period. 



It should also be noted that, in all of our tests covering three .seasons' 

 work with Scalecide applied to several varieties of apple, pear, cherry, 

 plum and peach, covering over two hundred trees, there has been disco^"- 

 ered no instance of injury which was in any wny attributable to the spray 

 applied. 



Publication of this Docujiext 



approved by the 



CosiMissioN ON Ad.ministratiox .\xd Finxxce 



.5000 3-26 Order 4443 



