16 X. H. Agr. Experiment Station [Bulletin 262 



Studies of contact angles, as recorded by the special photo-micro- 

 graphic apparatus developed, led to a plan by which a system of nu- 

 merical rating was devised, which would indicate the comparative per- 

 formance of a series of liquids on a given solid. This was worked out 

 mathematically and was published as Technical Bulletin No. 46, "A 

 Numerical Rating for the Contact Performance of a Spray Material." 

 At the close of this publication a table is submitted which derives a 

 definite contact rating from the measured angle of contact. This rat- 

 ing begins at 0, where the angle of contact is 180°, and rises to a rating 

 of 100 for an angle of contact of 1°. 



An extensive series of studies and measurements have now been 

 completed with the intent of determining the comparative perform- 

 ance of various so-called "wetting*" agents on various typical insects, 

 representing several orders. These studies have involved preparation 

 of accurately appraised materials, their application under control con- 

 ditions, the record of their performance as indicated by a long series 

 of photomicrographs, numbering several thousand, and finally the cor- 

 relation of results. The publication is in preparation. 



There is a strong tendency at the present time to substitute contact in- 

 secticides for stomach poisons in the control of various destructive and 

 widespread insects. Regardless of the nature of the toxic substance 

 employed for bringing about the death of an insect, its performance 

 and efficiency will be strongly influenced by the manner in which the 

 spray is able to extend itself over the surface of the insect and to pene- 

 trate into the tracheal tubes, and perhaps its ability to exert its effect 

 on the living insect cells in other ways. A given substance in a given 

 form or medium may be much more toxic than the same substance in a 

 "afferent form or medium. (Pumell Fund) 



Fertilizer in Orchards 



The belief of a few apple growers that it pays to divide the nitrogen 

 application into two parts half in early spring and half in early 

 mi 1111110- — is nol borne out by a five-year study conducted by G. F. 

 Potter. 



Experiments at Durham and Temple with Rhode Island Greening, 

 Baldwin and Mcintosh trees showed insignificant variations in the 

 amount of fruil bud format ion where two applications were made as 

 compared with the same total in the spring application. There were, 

 to he sure, indications that the percentage of blossoms setting fruit in- 

 creased slightly; evidently the niid-siiiiimer application is stored with- 

 in the tissues of the tree and is more readily available to the blossoms 

 during the period of fruil setting the following spring than is nitrogen 

 applied on the soil a week or two previous to opening of the bloom; but 

 !he difference in yield is doubtful and at best seems not sufficient to 

 justify the trouble. 



Studies were also made of plowing in a heavy phosphorus applica- 

 tion on seven plots of trees in the Woodman Orchard. Since soil 

 physicists now believe that phosphorus rapidly becomes fixed in the 

 soil and does not move downward appreciably, this phosphorus was 



