INSECTICIDE AND FUNGICIDE BOARD. 601 



During the fiscal year 192'2 a considerable number of powders and 

 blocks, composed essentially of paradichlorobenzene. were placed on 

 the market Avith the claim that tliey were effective disinfectants. An 

 investigation was therefore made by the bacteriologist of the board 

 of the effectiveness of paradichlorobenzene as a disinfectant. It 

 was found that pure powdered paradichlorobenzene was ineffective 

 against B. ti/phosus, both when used as a fumigant and in the pres- 

 ence of moisture. 



In August, 1921, a paper, of which the board microseopist was 

 joint author, was published in the Journal of the American Pharma- 

 ceutical Association, under the title " Domestic and imported vera- 

 trum (hellebore)." 



The plant pathologists of the board have continued investigations 

 with the more important types of fungicides to determine the amount 

 of active ingredients necessary for the contFol of the various dis- 

 eases against which they are to be used. The data obtained from 

 these investigations are proving very useful in enabling the board 

 to judge more nearly what can be expected of any product, based on 

 a knowledge of its chemical composition. 



Quite extensive experiments have been made with various types of 

 proprietary Bordeaux mixtures, giving special attention both to 

 the effects of variations in their copper content and to their phys- 

 ical properties. 



An investigation of some of the newer types of dusting mixtures 

 now appearing on the market as substitutes for liquid fungicides 

 has been conducted in several localities to determine their efficacy 

 against various fungous diseases and their effect on foliage of plants 

 and fruit trees. Special studies of the dry lime-sulphur products as 

 compared wath the liquid form are now under way to determine 

 their relative fungicidal values. 



The recent developments in the use of dust insecticides for the 

 control of sucking insects have led to a great increase in the number 

 of such preparations on the market. These insecticides are being 

 carefully tested by the entomologists of the board, and special stud- 

 ies are being made to determine facts necessary for the proper inter- 

 pretation of claims made in labels by manufacturers in reference to 

 nicotine dusts for the control of sucking insects. 



The work wnth calcium arsenate has been continued and special 

 attention has been given to the effect of this material, used alone 

 or with the standard fungicides, on the foliage of apple trees, shade 

 trees, and the ornamental plants. 



The dry substitutes for liquid lime-sulphur have been carefully 

 tested as to insecticidal value, in several different parts of the coun- 

 try and under widely varying conditions, and this work is rapidly 

 nearing completion. 



The tests with proprietary preparations recommended for the con- 

 trol of chicken mites and the experiments with miscellaneous mate- 

 rials against these mites have been completed, and these data are 

 now being assembled for publication. 



Special studies of naphthalene and pyrethrum have be:'n made 

 and a large series of tests carried on to determine the effects on 

 aphids of various percentages of these materials. 



In addition to experimental work, considerable useful information 

 has been obtained by visiting orchards and truck patches and ob- 



