98 



Flag Smiit of VJhcat. 



Infection and Treatment. 



The mode of infection has to be understood before methods of treatment 

 can be inteUigently appHed, and this is particularly the case in dealing with 

 Flag smut, which may either arise from the soil or the seed. A series of 

 experiments were therefore carried out at Burnley Horticultural Gardens 

 this season (1909) in order to test the effects of various modes of infecting 

 the seed and of different kinds of treatment, both before and after infection. 

 There were ten small plots altogether, each sown with 25 grains of the 

 Federation variety of wheat, on 30th June, 1909, and three of these were used 

 as a check or control plants to compare with the others. Both spores and 

 diseased straw were used for purposes of infection. The wheat was 

 thoroughly damped and rolled in the spores, while the diseased straw was 

 chaffed up into small pieces and placed around the seed when planted. The 

 following table gives the relative results : — 



Without laying too much stress on details, on account of the small size 

 of the plots, it is evident that infection may be produced either from spores 

 adhering to the seed or by means of diseased straw occurring in the soil where 

 the seed is sown. The addition of diseased straw to grain already dusted 

 with spores did not increase the virulence of infection. 



Again, when the seed was infected with spores and afterwards treated 

 with bluestone, the germinating power of the spores was destroyed, as the 

 resulting plants were all clean, and when the grain was treated with bluestone 

 before the addition of the spores no infection occurred. 



If, however, the grain was reated with bluestone and diseased straw 

 added, there was infection to the extent of 29 per cent. This could easily 

 be accounted for from the young shoots being attacked which had no pro- 

 tective coating of bluestone. Even when the grain was treated with 

 corrosive sublimate and diseased straw added there was . till a large 

 amount of infection. 



Thus, the general results already obtained are corroborated, that if the 

 spores are only on the grain and no Flag smut in the soil, treatment with 

 bluestone is a preventive ; but if the diseased straw is already in the soil 

 from a previous crop, neither treatment of the seed with bluestone nor 

 corrosive sublimate is effective. 



