184 MASS. EXPERIMENT STATION BULLETIN 279 



indicate that the purchase and use of a power sprayer solely for the application 

 of Bordeaux mixture to onions would be profitable in the average year in Massa- 

 chusetts. Since Bordeaux mixture, nicotine sulfate, and fish-oil soap are com- 

 patible and since the cost of spraying is not materially increased (only $L80 per 

 acre per application) by the inclusion of Bordeaux mixture 4:4:50 in this com- 

 bination, it is suggested that these materials be used when spraying to prevent 

 injury to onions by thrips. 



Summary 



Onions were injured by copper-lime dust in two out of three years, and loss 

 caused by blast was not lessened by this treatment. 



Bordeaux mixtures 4:4:50 and 8:4:50 were not injurious to onions when 

 applied with a suitable power spraj^er and at a pressure of 100 to 150 pounds. 



In the absence of downy mildew and blast, yields of onions were increased 

 somewhat by spraying with Bordeaux mixture. 



Milk of lime was less effective. 



The onset of blast was delayed, but not prevented by Bordeaux mixture. 

 In a year of blast, yields of onions were increased the most by four weekly appli- 

 cations of Bordeaux mixture 4:4:50. 



Increases in yield resulting from this treatment were not large enough to jus- 

 tify spraying onions every year with a copper fungicide alone under Massachu- 

 setts conditions, since downy mildew and blast are not present here every year. 



It is suggested, however, that growers spraying onions with nicotine sulfate 

 for protection against thrips include Bordeaux mixture in the combination spray. 



Literature Cited 



1. -Angell, H. R. 



1929. Puri)le blotch of onions {Macrosporiuni porri Ell.j. Jour. .\gr. 

 Research 38:467-487, illus. 



2. Bfatty, W. R. 



1915. Onion culture. U. S. Dept. Agr. Farmers' Bui. 354, 30 p., illus. 



3. Bourne, .\. 1. 



1929. Spraying for the control of onion thrips. .Jour. Econ. Ent. 

 22:679-()S3, illus. 



4. Butler, O. 



1922. Bordeaux mixture II. Sfiiruilatory a(;tion. N. H. Agr. Expt. 

 Sta. Tech. Bui. 21, 50 p. 



1927. Hand spraying and hand dusting potatoes. N. II. .\gr. Expt. 

 Sta. Circ. 26, 16 p., illus. 



6. Chupp, Charles. 



1925. Manual of vegetable-garden diseases. 647 p., illus. New York. 



7. Hansen, II. N. 



1929. Etiology of the pink-root disease of onions. Ph^i.opath. 19:691- 

 704, illus. 



