March, 1928] AGRictrLTURAL experiments 1927 33 



Impregnated Oils 



The increased numbers of browntail moths for several seasons has 

 brought up the question of control of this pest by spraying. Some years 

 ago entomologists recommended application of a poison spray to the 

 foliage about the first week in August, in order to kill the young browntail 

 caterpillars before they had spun their winter webs. Under restrictions 

 now prevailing, as to applications of poison sprays to fruit trees bearing 

 fruit of considerable size, this means of control of the browntail must be 

 discarded if the spray applied is a mineral poison such as an arsenic 

 compound. New developments in spray materials have pointed to 

 possible use of white oils impregnated with organic poisons such as those 

 derived from pyrethrum. 



Other insects have been brought under observations, including the 

 Colorado potato beetle, the imported cabbage worm, the squash bug, the 

 tarnished plant bug, and the fall web worm. The percentage of kill 

 secured in each case is relatively high. One interesting result is an indica- 

 tion that the creep of the material as influenced by additions of small 

 amounts of soap, for example, has an important bearing on its toxicity. 

 It is planned to continue these studies in considerable detail. (Hatch 

 Fund.) 



Arsenical Residue 



Four plots of mature Baldwin trees were sprayed carefully in order to 

 determine the average amount and variability in quantity of arsenical 

 residue which will adhere to the fruits at harvest time under the climatic 

 conditions of southern New Hampshire. This work is being conducted 

 co-operatively by S. R. Shinier and (1. F. Potter. (Purnell Fund.) 



Apple Storage 



A study of storage problems, particularly those of the Mcintosh and 

 Baldwin apples, is being conducted by L. P. Latimer. 



Experimental work was begun at the end of the Baldwin harvest season. 

 Little can be reported at this time, but it is evident that a study of the 

 changes in the electrical conductivity of the tissue and juice during 

 storage will afford a means of detecting physiological changes incident to 

 the ripening of the fruit and related to its storage life. (Hatch Fund.) 



Studies of White Pine Weevil 



In the summer and fall of 1926 the life history and habits of the white 

 pine weevil in New Hampshire were given detailed study. This was 

 continued for the season 1927. Several gaps in the known life history 

 were filled. Some parasitic enemies were discovered that had not 

 previously been found in the study of this insect in New Hampshire. 

 Observations were made on the dispersion habits of the adults, especially 

 as these have a bearing on reinfestation of a plantation following control 

 measures. (Purnell Fund.) 



