ao March, 1909.] Tlic Stinking Smut of W'licat. 171 



THE STINKING SMUT OF WHEAT. 



D. McAlpine, Vegetable Pathologist. 



I. — Answers to Questions. 



In my forthcoming work on The Smuts of Australia there will be a 

 full account of the various smuts which attack cereals as well as other 

 plants, together with the best methods of treatment. The stinking smut 

 •of wheat holds a prominent place on account of its special economic im- 

 portance, and I have selected for publication a portion of the work dealing 

 Avith the answers to a number of questions which the farmer naturally 

 puts to himself. 



Now that the sowing season will soon be on. it is important that he 

 should know the essential points in connexion with this smut in order that 

 he may take the necessary precautions to insure his crop being free from 

 the disease. 



This particular smut has been treated at some length, because it is the 

 form with which the farmer is most familiar and it appeals to him as the 

 type of smuts in general. Therefore it has been deemed advisable, by 

 way of summary, to conclude by clearly stating a number of questions 

 which he consciously or unconsciously asks himself, and answering them 

 as far as observation and experiment will permit. 



It is of fundamental importance for him to realize at the outset that 

 the smut plant is a fungus which develops from spores that are the 

 •equivalent of seeds in other plants, and that this plant grows as a parasite 

 within the wheat plant until it reaches the grain and there produces its 

 fruit or masses of spores (ball smut) similar to those from which it started. 

 In order to grow and develop proi>erly, this smut plant is dependent on 

 ^surrounding conditions, just as much as the wheat-plant itself, and if we 

 imderstood those conditions, it would explain why the spores sometimes 

 germinate and sometimes do not, why the smut plant sometimes reaches 

 maturity and forms its spores and sometimes does not, just as the seed- 

 wheat may or may not germinate and the seedling may or may not reach 

 anatiurity. 



It is also of prime importance to remember that the wheat is only 

 infected in the seedling stage, just as the young plant emerges from the 

 seed beneath the surface of the soil. Consequently, no infection can come 

 through the air, unless indeed the grain germinates upon the surface of 

 the ground and when it is properly planted only the spores adhering to the 

 seed can produce the disease. The farmer sometimes sees or fancies he 

 sees smut spores upon his fences and when he has treated his wheat after 

 a fashion and the smut still appears, he tells you that it was blown from 

 the fences. But when the wheat plant is above ground, it is proof against 

 infection from bunt spores, so that there must be some other reason for 

 the failure of the treatment. 



There are questions sometimes put by the farmer, howe\er, which can- 

 not receive a definite answer, because his experience does not always take 

 note of the accompanying conditions and because his love of paradox some- 

 times overrides his experience. I am often asked by farmers, " Why is 

 one part of a paddock of wheat smutted and the other not, the seed in 

 each case being treated properly and sown at the same time? " It all 

 •depends here on what is meant by proper treatment of the seed, as it is 

 implied by the question that the fault must lie in the soil. But it is 

 found by experiment that when the seed is properly treated with bluestone 

 solution and all the smut-balls removed, there is no smut in the crop, even 



