Loose Smut of Wlicat. 87 



Infection. 



It has generally been taken for granted that the wheat snint, like the 

 oat smut, only infected the youn;^; seedling, and that the fully-developed 

 plant was immune. It was assumed that the spores fell to the ground, 

 retained their germinating power there, and that they caused infection the 

 next season in the young seedling. This view was rendered probable from 

 the fact that in some of the smuts, as will be shown in the case of flag smut, 

 the spores in the soil infected the young plant, so that treatment of the seed 

 did not prevent the appearance of the smut. Another view was that the 

 spores reached the flower and there remained on the seed which was formed 

 until the next sowing season, but, unfortunately for this view, the spores 

 only retain their germinating power for a few months. All these conflicting 

 views were finaUy disposed of when Brefeld and Hecke carried out their 

 conclusive experiments, and showed that infection took place through the 

 flower and not through the seedling. Previous to this, however, it had been 

 experimentally proved by Maddox, in Tasmania, that flower infectioai 

 occurs. 



It is well known to every agriculturist that, when grain is dressed for 

 stinking smut or bunt, the dressings have no appreciable effect on loose 

 smut, and in my experiments with bluestone and formahn treatments I 

 have always found this to be the case. This fact can be easily explained 

 when it is remembered that the source of invasion is from within, and it is 

 not reached by the dressings usually employed. The mycelial filaments are 

 so intimately bound up with the living cells of the embryo that the destruction 

 of the one would involve the death of the other. 



The only feasible measures for this disease at present seem to be to select 

 seed from crops free from the disease, and at a sufficient distance from any 

 diseased crop, so that air-borne spores could not be carried at least in any 

 great quantity. Also, as in the case of rust, to endeavour to breed a race 

 of wheat capable of resisting the disease. Quite recently the hot-water 

 treatment of the seed has been found effective, both in Loose smut of Wheat 

 and Naked smut of Barley. 



