BETTER FRUIT 



AN ILLUSTRATED MAGAZINE PUBLISHED MONTHLY IN THE INTEREST OF MODERN, PROGRESSIVE FRUIT GROWING AND MARKETING 



The Compatibility of Insecticides 



Mr. George P. Gray, before the Slate Fruit Growers' Convention, Davis, California, June l-U, 1914 



THE cost of crop-pest insurance by 

 means of spraying is no small bur- 

 den to most producers, who are 

 often confidiited with the necessity of 

 making fre(|uent applications of various 

 remedies to insure their products 

 against the ravages of insect and fun- 

 gous parasites. At times it nurst almost 

 seem that if the necessary thought and 

 time were given to the proper applica- 

 tion of the appropriate treatment at the 

 right time little energy would be left 

 for cultivation, harvesting or other 

 necessary operations. The cost of 

 spray materials is no small item, but is 

 usually insignificant as compared to the 

 cost of application. One way of re- 

 ducing the latter expense is by combi- 

 nation spraying, that is, by mixing two 

 or more spray materials and applying 

 them together. In mixtures of this sort 

 grave chemical changes may take place 



of combination sprays and the results 

 have been published in the bulletins of 

 the I'nited States Department of Agri- 

 culture, the state experiment stations 

 and in agricultural journals. These re- 

 ports are scattered through so many 

 publications and the conclusions are at 

 times so conflicting that no inconsider- 

 able amount of time must be spent in a 

 search of the literature to arrive at a 

 definite conclusion as to the suitability 

 of applying some particular remedy in 

 combination with another. In order to 

 bring this information into more avail- 

 able form and of more easy access, it 

 has been condensed into tabular form 

 and a compatability table is pre- 

 sented for your consideration with the 

 hope that it will be of some assist- 

 ance in warning you of obscure dan- 

 gers that may lurk in apparently harm- 

 less mixtures. 



COMPATIBILITY TABLE— INSECTICIDES AND FUNGICIDES 



Acids D C D 



Alkalies B C D 



Class 



A-l-Better results by mixing Compatible 



A— Properties not changed by mixing 



B— Efficient, non-injurious 

 C— Inefficient, non-Injurious 

 D— DANGEROUS MIXTURE 



Incompatible, chemioally 

 [Arranged by Geo. P.Gray] 



which render the mixture wholly unfit 

 for use. On the other hand, the orig- 

 inal ingredients may remain unchanged 

 or may be improved by their new asso- 

 ciates. Numerous experiments have 

 been made to determine the advisabilitv 



The word "compatibility" or its oj)- 

 posile, "incompatibility," may seem odd 

 as used in this connection, but it seemed 

 to be the best word that presented 

 itself, applied in the sense to be later 

 described. "lncomi)atibility of tem- 



perament" is a phrase often seen in the 

 newspapers, and its meaning may be 

 described as a state of affairs in which 

 trouble is precipitated whenever two 

 opposing tempers come in contact. In- 

 compatibility is the state of being in- 

 compatible. In pharmacy the terms 

 are often used, and usually a whole 

 chapter is devoted to the subject in 

 works on the practice of pharmacy. As 

 applied to medicines, incompatibility is 

 of three difTerenf types and may be de- 

 fined as follows: Incompatible: (1) 

 Chemically — Not capable of being 

 united in solution without liability 

 to decomposition or other chemical 

 change. (2) Therapeutically — Not suit- 

 able to be prescribed together because 

 of opposing medicinal (pialities. {3) 

 Physically — Not suitable to mixed on 

 account of liability to produce unde- 

 sirable physical change. In a broad 

 sense, it seems that the word may be 

 applied to insecticides and fungicides. 

 The distinctions made between the dif- 

 ferent sorts of incompatibilities as ap- 

 plied to pharmacy might also be applied 

 in a general way to spray mixtures. To 

 avoid technicalities, however, it seems 

 best to divide mixtures of insecticides 

 and fungicides into five classes desig- 

 nated by letters. 



Classification of Mixtures 



The key to classification is briefly 

 given at the bottom of the table for con- 

 venient reference. A little fuller state- 

 ment is desirable and is as follows: 



Class A-l, compatible mixtures in 

 which the chief constituents remain 

 practically unchanged but are less 

 liable to decomposition after applica- 

 tion, or in which an undesirable con- 

 stituent has been neutralized or ren- 

 dered less soluble. Mixtures in which 

 the spreading or adhesive (lualities are 

 improved are also iiuhidid in this 

 class. 



(Hass A, compatible mixtures in 

 which no important chemical or phys- 

 ical changes occur. 



Class B, incompatible chemically, but 

 compatible in respect to use ("thera- 

 peulicnlly" and "physically"). Klli- 

 cicnl, non-injurious. Mixtures in which 

 important rheniical changes occur but 

 the original killing or iircventive prop- 

 eiiies and i)hysical i)roi)erties are not 

 impaired, and no injurious new com- 

 pound is formed. 



("lass C, incompatible chemically 

 and also incompatible in rcsiicct to 

 use ("therapeiilicalh " oi' "pli\ sically" 

 or both). Inellicient, non-injurious. 

 Mixtures in which imporlant chemical 

 nr phxsical changes occur and render 

 a part or all of the original ingredients 



