REVISED COMPATIBILITY CHART OF INSECTICIDES 

 AND FUNGICIDES 



The present high cost of supplies and the scarcity of labor have 

 brought the agriculturalist face to face with many new problems, not 

 the least of which is that of pest control. With the exception of 

 cyanide fumigation, the cost of an insecticide or fungicide is usually 

 much less than the cost of its application. Spraying operations are 

 often limited to a short space of time on account of unfavorable 

 weather. The tendency to use, whenever possible, combination sprays 

 in the control of two or more pests is thus accentuated. Untried com- 

 binations are apt to be made use of, sometimes with disastrous results 

 to fruit and foliage. The matter of the compatibility, or incompati- 

 bility, of insecticides and fungicides, therefore, is now of unusual 

 interest. In complex mixtures of this sort grave chemical or physical 

 changes may take place which render the combination wholly unfit 

 for use. On the other hand, the original ingredients may remain 

 unchanged, or may be improved by their new associates. 



Numerous experiments have been made to determine the advisa- 

 bility of various combination sprays and many of the results have 

 been published in bulletins of the U. S. Department of Agriculture, 

 the state experiment stations, and in agricultural journals. These 

 reports are so scattered, and at times the conclusions of the various 

 investigators are so conflicting, that one must spend much time in 

 a search of the literature before arriving at a definite conclusion. In 

 order to bring this information into more available form and to make 

 it more easy of access, it was condensed into tabular form and pre- 

 sented before the State Fruit Growers' Convention in assembly at 

 Davis, June 1-6, 1914. It is believed that this compatibility table and 

 its discussion was the first comprehensive one of its kind ever made 

 public. It was therefore presented with no little hesitation, and was 

 considered as a tentative one only. Some little publicity was later 

 given the table through its publication in at least six agricultural 

 publications. Discussion and criticism were invited so that if any of 

 the classifications were incorrect, or did not correspond with practical 

 experience, the faults could be corrected. Since then, the matter has 

 been followed closely, and minor corrections have been made to cor- 

 respond more closely to the best practice. The original table has been 

 simplified and arranged in the form of a circular chart, 1 and is now 

 believed to be an accurate reflection of the best thought of the various 

 investigators who have worked on the subject of compatibility of in- 

 secticides and fungicides. The accompanying revised chart is pub- 

 lished in the hope that it will be of value in indicating the sprays 

 which can be applied in combination, thus reducing the cost of ap- 

 plication one-half, or in warning of clangers in apparently harmless 

 mixtures. 



i The writer is indebted to Prof. C. A. Noren, Oregon Agricultural College, for 

 suggesting the circular arrangement of the chart. A circular chart based upon 

 the writer 'a original table and investigations by Mr. W. C. Morris, Hastings, New 

 Zealand, has been published in the New Zealand Journal of Agriculture, vol. XII, 

 no. 3, p. 193, and in the Fruit World of Australasia, vol. XVIII, no. 10, p. 17. 



