1906.] 



Dodder. 



337 



11. In the Comptes rendus de V Academie des Sciences, M. 

 Garrigou called attention in 1904 to the value of calcium 

 sulphide as a means of combating dodder and other parasites. 

 In this connection he says " One may, with this parasiticide, 

 cause the dodder completely to disappear in two days. A 

 few hours afrer it has been sprinkled with calcium sulphide 

 the dodder commences to blacken and wither, and, forty- 

 eight hours afterwards, above all if the weather has been 

 somewhat damp, it is completely destroyed." M. Garrigou's 

 experiments show that this substance is very clearly superior 

 to sulphate of iron. 



12. Above all good cultivation in the widest sense should 

 prevail, and all fields, hedges and ditches should be kept clean 

 and free from weeds. 



Dodder in other Countries. 



United States. — In the United States of America dodder is 

 considered a most troublesome pest, and clover and lucerne 

 seed appear to be very frequently impure from this cause. 

 According to a circular issued by the United States Depart- 

 ment of Agriculture in May, 1906, 521 samples of the seed 

 of red clover were obtained in the open market and examined. 

 No less than 116 samples (or over 22 per cent) were found to 

 contain the seed of dodder. In the seed exported to this 

 country, however, dodder is hardly known. 



South Africa. — Dodder alsD prevails in the South African 

 Colonies, and according to an article in the Transvaal Agri- 

 cultural Journal for April, 1906, the pest is gradually spreading 

 in the Transvaal, owing to the persistence of the farmers in 

 using poorly-cleaned seed. 



France. — So great is the loss due to dodder in certain parts of 

 France, says M. Marre, that he dare not attempt to estimate it, 

 for fear he should be charged with exaggeration. The excessive 

 development of the pest in 1904 led to the promulgation of 

 regulations for its destruction.* 



Germany. — In Germany dodder causes much trouble, and 

 Thaer, writing in 1905, says that owing to dodder it is almost 

 impossible to grow red clover and French lucerne in some 

 districts of Germany. In the same way, he adds, a great part 



* See Journal, March, 1906, p. 742. 



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