AGRICULTURAL RESEARCH IX NEW HAMPSHIRE 35 



Crosses have l^een made between cultivated varieties of peaches and 

 certain seedHngs secured from the North Caucasus region of Russia by the 

 United States Department of Agriculture. The object is to secure greater 

 hardiness in peaclies. 



Hybrids have been made between Amygdalus nana, Siberian Almond, 

 and varieties of almonds from California. The seedlings have thus far ap- 

 peared hardy, although they have not reached bearing age. A plot of con- 

 siderable size of butternuts raised from the best trees in this area have been 

 planted and are nearing bearing age. 



Crosses have been made between ^Mcintosh and Winter Banana and 

 between Alacoun and Northern Spy apples. These young trees are grow- 

 ing. The objective of this work is to obtain high-quality, late winter 

 varieties. 



A. F. Yeager, L. p. Latimer 



Some crosses have been made between Clapp's Favorite and Confer- 

 ence pear, with the object of producing a later variety which has the good 

 qualities inherent in Clapp's Favorite, namely vigor and heavy annual 

 production. 



A. F. Yeager. R. Eggert 



INSECT CONTROL 



Needs of the war emergency have set the pattern for the research pro- 

 gram in the Department of Entomology. The aim has been to produce 

 materials that might help to control insects that damage food crops, or 

 those that attack human beings, and at the same time to accumulate data 

 that will shed light on fundamental facts. 



In a study of a long series of syntJietic organic compounds, two groups, 

 which give promising toxicity against insects that attack human beings, 

 have been discovered. Optimum members of each group, when dissolved 

 in a household-spray kerosene give exceptional performance against flies 

 and mosquitoes, and thus can help to control pests which not only are 

 annoying but are potential carriers of serious human diseases. In the study 

 of these two groups of chemicals many homologues were examined. In- 

 formation, indicating the molecular configuration which contributes toxic- 

 ity, was secured. One member of each group is more potent as a toxicant 

 than is to the standard pyrethrum extract. 



A technique was devised for observing the "knockdown" performance 

 of new chemical compounds — or. in other words, the ability of a spray 

 to cause paralysis of the house flies used as biological indicators. An en- 

 closure which has glass sides and thus permits unobstructed observation 

 is utilized. The liquid under study is atomized in measured amounts 

 through an orifixre in the bottom of the enclosure. Flies are introduced 

 through an opening in the top. The length of time required for partial and 

 for complete knockdown is recorded. 



The new chemical compound designated as D D T (dichlor diphenyl 

 trichlorethane) was given intensive study. Many formulations involving 

 this chemical were devised and tested. These included both liquids and 

 dusts. Satisfactory solvents for incorporation of the chemical in a liquid 



