414 Agricultural Journal of Victoria. 



of its spread in the nortliern districts of Victoria lies in the vast 

 amount of dust that has been blown over large areas. It has to be 

 seen to be realised how the blown dust accumulates in such quantities, 

 wherever it is intercepted, as to bury fences out of sight, and it 

 was no unusual thing duriug my visit in November to drive over 

 buried fences. This is no doubt a fi-uitful source for spreading the- 

 fungus, and it may appear in any class of soil under those conditions. 

 There is no ditticulty then in accounting for wheat-plants becoming- 

 infected, and since the fungus spreads from a centre, the disease 

 generally occurs in patches, or it may be on isolated plants, which, in 

 after years, would form the centres of take-all patches. Then according 

 to the virulence of the attack and the condition of the plant, the- 

 latter succumbs at an eai'ly stage of its growth, or it may be able to- 

 grow in spite of the fungus and fully form its ears without being able 

 to produce grain, or in some exceptional cases it may even proceed 

 to the formation of grain. But ultimately the root and base of stem 

 being attacked, the plant dies before reaching its full development, and 

 thus there may arise the take-all patches when the young plants have- 

 been overcome by the fungus, or white-heads, when the plants have 

 had sutficient constitutional vigour to resist the fungus for a more 

 lengthened period. Sooner or later, however, the plants attacked are 

 destroyed, and then the fungus proceeds to prepare for its next 

 campaign by producing its reproductive bodies on the dead roots in 

 the soil, or on the butts of the stems just above the soil. 



Various Causes Assigned- 



It was only to be ex{)ected that such a widespread and destructive 

 disease should attract attention, and numerous theories were advanced 

 to account for it. In the report of the South Australian Commission (1) 

 already referred to, a summary is given of the views then held, and 

 they fairly represent the conflicting opinions which still prevail. " It 

 is said to result from an exhausted soil — from the presence of too 

 much salt in the soil — from the deficiency of some constituent element 

 essential to the maturing of cereal crops. It is declared to be want 

 of drainage, and it is said to be want of manure. It is affirmed to^ 

 be caused by a vegetable fungus, and to be a disease analagous 

 to the potato disease. It is also said to be the result of insect ravages. 

 Scarcely any two witnesses agree on this point, whether farmers or 

 chemists." It was also believed to be in the seed, and there is thus 

 a fairly large number of explanations to choose from. 



First, it was thought to be in the seed, but this view was disproved 

 by the fact that the same seed grew perfect plants alongside of 

 deseased patches, and even in these patches the seed germinated 

 properly at first. The disease was evidently due to something outside 

 the seed. 



Second, it was commonly believed to be due to the want of some 

 constituent or constituents in the soil, necessary to the healthy growth 

 of the wheat-plant; in fact that it was a poverty disease. The 

 occui'rence of the disease in patches seemed to militate against this 



