Flag Smut of Wl/cat. 



91 



year a much heavier yield, but the season is generally blamed for the shortage. 

 As will be shown afterwards, the twisted and curled leaves breaking up and 

 falling to the ground are the main sources of infection for next season, and 

 it can readily be understood that where wheat is grown year after year and no 

 nrecautions taken against this disease the effects are cumulative. This will 

 f^;CC0unt for the widespread and injurious effects of this disease in many 

 w^heat-growing districts. 



Conditions favouring the Disease. 



In the evidence given by farmers before the Commission on Cereal Diseases 

 in South Australia in 1868, various conditions and causes were assigned for 

 this disease. Early and self-sown crops were said to suffer most, and all 

 loose and richly-manured lands were supposed to be very liable. Ploughing- 

 in the straw was also said to encourage it, and early sowing, combined with a 

 spell of dry weather, was sure to bring the disease. Hence late sowing and 

 wet soil were recommended for its prevention, as it was generally understood 

 the later you sow the less likely you are to have it. 



Among Victorian farmers it is also held that dry sowing is more subject 

 to the disease than wet, and one even went the length of saying that when 

 wheat was so^vn in very wet ground there was no flag smut. The lighter 

 ground is generally found to be the worst, and it is said that virgin ground, 

 in districts liable to this disease, generally bears two clean crops while the 

 third is attacked. This probably means that the disease has spread suffi- 

 ciently in the third crop to make it noticeable to the farmer as being in- 

 jurious. 



The effect of early and late sowing, as well as of a dry and a comparatively 

 moist seed-bed on the appearance of flag smut, was put to the test in 1907. 

 Wheat was purposely sown on 24th April, when the ground was dry, on land 

 which had borne a crop of wheat badly flag-smutted the previous season. 

 There was practically no rain till June, when about an inch fell on the 20th. 

 This rain sr^ems to have germinated the seed-wheat and the fungus spores at 

 the same time, giving thereby a heavy proportion of diseased plants, up to 

 14 per cent. Alongside the early-sown plots a second sowing was made on 

 16th July, about a month after the rain. The ground at sowing time was in 

 excellent order, and it was a remarkable fact that at harvest the proportion 

 of diseased plants, taking all the late-sown together, averaged only 1 per 

 cent. The conclusion to be drawn from such a test is that early sowing in 

 a dry seed-bed following a dry summer is favorable to flag smut, since spores 

 and seed germinate together when the rain comes. On the other hand, if 

 the soil is moist and has been so for some weeks, most of the flag-smut spores 

 appear to have lost their effective power. These conclusions were supported 

 by results in the general crop on the farm, and these views so strongly confirm 

 those of the farmers that they practically amount to proof. 



Conditions occurring in a 'particular Crop. — In the north and north- 

 eastern districts of Victoria the flag smut was very prevalent during 1906, 

 and was largely responsible, together with Take-all {Ophiobolus qraminis). for 

 the falling-off in the promised yield of many of the wheat crops. The con- 

 ditions under which it occurred were very closely followed, and the particulars 

 regardinjr it will be given for one district as a fair sample of the whole. In a 

 50-acre paddock near Wilby the Pur])le Straw Wheat was badly affected with 

 flag smut, so much so that what promised to be a 20 to 24-bushel crop only 

 turned out 8 bushels per acre. When inspected in the middle of November 

 the general impression was that of a fine crop, but for the numerous plants 

 scattered through it without ears, owing to flag smut. The conditions under 

 which the crop was grown and all the defects conducted with its cultivation 



