BASIC COPPER SULFATE AS A FUNGICIDE 147 



sulfate dusts (3.00 per cent Cu) and a copper-lime dust (4.28 per cent Cu) were not 

 equal to lime-sulfur in controlling scab on Baldwin, Mcintosh, Northern Spy, 

 R. I. Greening and Tompkins King apples in 1928 as determined by fruit counts on 

 Mcintosh, although none of the fungicides gave satisfactory control on either 

 fruit or foliage, probably because of too late application. Basic sulfate dusts 

 did not injure the foUage appreciably, but russeted Mcintosh apples a little more 

 than lime-sulfur. 



The effectiveness of low basic sulfate sprays (0.13, 0.19 and 0.25 per cent Cu) 

 on Moore's early grapes in 1926 could not be determined in the absence of disease. 

 The injury to foliage increased with the concentration but was not appreciable on 

 the fruit (Roberts). The relative effectiveness of spray (0.06 and 0.19 per cent 

 Cu) and dust (2.50 and 5.00 per cent Cu) applications of mixed basic sulfates and 

 of Bordeaux (0.24 per cent Cu) in controUing mildew and black rot on Worden 

 grapes in 1927 could not be determined, as practically no disease developed. The 

 leaves remained green 10 to 14 days longer with basic sulfates than with Bordeaux, 

 and complete defoliation was equally delayed. The dilute dust caused practically 

 no injury to the foliage, the dilute spray a little, the concentrated dust and spray 

 considerable and Bordeaux most of all. With the latter the "burned" condition 

 was decidedly apparent. Low and high basic sulfate sprays (0.07 per cent Cu) 

 and dusts (3.00 per cent Cu) and dilute Bordeaux (0.07 per cent Cu) were applied 

 to Worden grapes in 1928, but their effectiveness could not be determined in the 

 absence of disease. There was some foliage injury without marked differences. 

 The least was probably on the check, followed by the basic sulfate dusts, Bordeaux 

 and basic sulfate sprays. 



Low basic sulfate spray (0.25 per cent Cu) was applied to currants, English 

 gooseberry, nine varieties of grapes, tea roses and phlox in 1926 without injury 

 being observed (Brooks). Low basic sulfate spray (0.16 per cent Cu) did not 

 injure rhododendron seedlings in flats (Ivinney). 



As to supplementary products, Wilkinite proved of little value except possibly 

 to increase visibiUty. Saponin was of value in increasing wetting and spreading, 

 and raw Unseed oil in increasing adhesiveness The oil was the most promising. 

 It mixed well and the spray residue adhered firmly to the foliage and fruit of apples 

 and grapes (Cutler, Roberts); while on cucumbers, celery and potatoes, oil 

 was not approved (Guba, Cubbon). The dusts with talc as the vehicle distributed 

 well (Guba, Drain) and appeared to have good adherence (Drain). 



Summary and Conclusions 



1. Commercial basic copper sulfate has proved effective in controlling disease 

 on cucumbers and celery and promising on potatoes, but requires further demon- 

 stration on orchard fruits and grapes. 



2. A greater "copper" concentration of basic sulfate than of Bordeaux is 

 necessary in some instances to assure equal control, due to the lower dispersion. 



3. The low basic sulfate appears to be slightly more effective per unit of copper 

 than the high basic sulfate, probably because the physical condition has averaged 

 better. 



4. The concentration necessary in sprays differs widely from that needed in 

 dusts, as the large proportion of inert vehicle in dusts depresses the activity of the 

 fungicide. The following concentrations of basic copper sulfate and of lead 

 arsenate in sprays and dusts are suggested tentatively for field practice. 



