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recent investigator claims that the acidity of the cell sap is the factor 

 that enables plants to resist parasitic fungi. The problem of resistance 

 is in an unsettled condition at present. It may be, however, that the 

 problem is one of toxins in host or parasite or in both, but this is only 

 speculation. 



Control of the Rusts. Spraying experiments for the prevention 

 of the rusts have been for the most part unsatisfactory, and even if valu- 

 able would not be practicable in large fields. Usually grain that matures 

 early is not so severely injured as later maturing grain, so that early 

 seeding is generally advantageous from the standpoint of rust control. 

 The destruction of the buckthorn and barberry may help to lessen the 

 severity of the rusts, but need not be expected to prevent their occurrence. 

 The varieties of grain that are found by trial to be the most rust resistant 

 should be grown. 



