Some Comparisons between Calcium Arsenate and Lead Arsenate as General Insecticides for Apple1

1934 ◽  
Vol 27 (2) ◽  
pp. 421-431
Author(s):  
P. J. Chapman ◽  
G. W. Pearce ◽  
R. W. Dean ◽  
O. H. Hammer
Keyword(s):  
Lead Arsenate ◽  
Calcium Arsenate

The fungicidal properties of certain spray-fluids, V

1929 ◽  
Vol 19 (3) ◽  
pp. 405-412
Author(s):  
W. Goodwin ◽  
H. Martin ◽  
E. S. Salmon
Keyword(s):  
Calcium Hydroxide ◽  
Lead Arsenate ◽  
Calcium Arsenate ◽  
Lime Sulphur ◽  
Conidial Stage

(1) A solution of dicalcium hydrogen arsenate at a strength of 0·0125 per cent. As2O5 was fungicidal to the conidial stage of Sphaerotheca Humuli, while at 0·006 per cent. As2O5 it was not quite fungicidal.(2) Lime casein containing calcium hydroxide when added as a spreader to calcium arsenate was shown to reduce the fungicidal properties of the calcium arsenate spray.(3) A solution of calcium thioarsenate at a strength equivalent to 0·006 per cent. As2O5 was fungicidal to the above fungus, while at 0·003 per cent. As2O5 it was below fungicidal strength.(4) It is suggested that the increased fungicidal properties of the mixed lime sulphur-lead arsenate spray are due to the presence of calcium thioarsenates.

Bordeaux mixture in combination with arsenical sprays

1928 ◽  
Vol 18 (3) ◽  
pp. 460-477
Author(s):  
WM. Goodwin ◽  
H. Martin
Keyword(s):  
Carbon Dioxide ◽  
Calcium Hydroxide ◽  
Bordeaux Mixture ◽  
Hydrated Lime ◽  
Equivalent Amount ◽  
Not Given ◽  
Arsenic Compounds ◽  
Lead Arsenate ◽  
Calcium Arsenate ◽  
Arsenical Compounds

1. The interaction of Bordeaux mixture with lead arsenate and with calcium arsenate has been studied by an examination of the effects which are produced:(a) When hydrated lime is added to the arsenical compounds.(b) When copper sulphate is added to the arsenical compounds and hydrated lime.2. The nature of the interaction of calcium hydroxide and diplumbic hydrogen arsenate has been shown to be most complex and to result in the complete decomposition of part of the lead arsenate and th e formation of basic calcium arsenates.3. Support is not given to the view that calcium carbonate decomposes diplumbic hydrogen arsenate with the production of soluble arsenic compounds.4. When the lead arsenate, in water, is allowed to interact for long periods with excess of hydrated lime, the amount of basic calcium arsenates formed is such that large quantities of arsenic are brought into solution by the action of carbon dioxide.5. Under conditions when the calcium hydroxide is rapidly converted to the carbonate the amount of arsenic rendered soluble is slight.6. The conclusion is formed that in actual spraying there is a definite reduction of the risk of arsenical injury when hydrated lime is added to lead arsenate and to calcium arsenate.7. It is concluded that when the conditions are such that the addition of hydrated lime brings about a reduction of arsenical injury, the use of an “equal-lime” Bordeaux mixture containing an equivalent amount of calcium hydroxide will prove far more effective.

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