•25 a 



Journal op the Dbpartmknt op Agriculture. 



how it is divided internally into a number of compartments or cells, 

 two in this case, and surrounded by a jacket of smaller, lighter- 

 coloured cells outside, which protects it from the effects of prolonged 

 diought. The spores are produced in the tissues of the leaves and are 

 visible internally as the black streak previously mentioned, and are 

 liberated as a black, sooty powder. (See Fig. 2.) 



Infection. 



Infection of the wheat plant probably takes place when it is in 

 the seedling stage, through spores of the fungus which are present in 

 the soil. Each spore germinates by sending out a short germ tube at 

 the end of which a number of daughter spores are formed. These 

 are much smaller than the mother spore, and each is able to infect the 

 growing tissue ot' the wheat plant. The fungous threads, known 

 collectively as the mycelium of the fungus, permeate the tissues of the 



Fig 5. 



wheat plant and cause the stunted growth and distortion of the stalks 

 and the leaves. Ultimately, wlien the food supply provided by the 

 host begins to be exhausted, the mycelium divides up in various ways 

 to form the spores, which turn black. The -wheat-plant, if badly 

 diseased, is, as a rule, killed at this stage, and many of the spores find 

 their way to the soil, where they rest "and lie in wait" for next 

 season's wheat crop. 



Pre VENTi VE Measures . 



As infection comes from spores present in the soil, it can be 

 understood that the usual treatment of the seed with chemicals, such 

 as formalin, etc., which are used for the control of other cereal smuts, 

 is not going to be much help. This treatment is of value, however, 

 in that any smut spores adhering to the seed coat would be killed, and 

 thus the danger of introducing the disease into clean lands would be 

 lessened to some extent. 



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