596 PROCEEDINGS OF SECTION G". 



11. — Flag Smut of Wheat (Urocystis tritice, Koern). 



Flag Smut, as the name denotes, is most commonly found 

 on the leaves and leaf- sheaths in the form of elongated streaks, 

 but it may also occur on the stem, and even on the chaff, but 

 very rarely in the ovary. It is sometimes called " Black Rust," 

 but this nam© is so misleading, inappropriate, and confusing that it 

 should be utterly discarded. This disease is weil known in South 

 Australia, Victoria, and New South Wales, and occurs (■even i^ 

 Queensland. I am informed by the Vegetable Pathologist there that 

 only a single instance of it had come under his notice, in 1906, in a 

 wheat crop gro^vn in the heavy soil of the Hodgson district. Howevei', 

 this does not imply that the disease was confined to this one spot, for 

 lie guardedly remarks '' that it may have been more prevalent than 

 is indicated by this statement, since farmers are not in the habit of 

 calling attention to affections in their crops until these are sufficiently 

 pronounced to cause them some concern." 



In South Australia, where the disease has long been known in 

 the wheat crops, it is regarded as being in some seasons quite as 

 injurious as the nist itself. In Victoria, as much as half the crop 

 may be lost through it, and in one affected paddock I found that the 

 produce of an average square yard of crop consisted of 144 smutted 

 straws without ears, and sixty-two clean straws with ears. 



The infection experiments were carried out to determine — 



1st. If the Flag Smut of rye is the same as that of wheat. 



2nd. If the infection occun^ed in the seedling stage, or later on, 

 since the wheat^plant is generally destroyed by this smut 

 before the flowering stage is reached. 



■5rd. If spores in the soil can infect the wheat-plant. 



/. — Infection of Wheat and Rye. 



Although this disease has been known in Australia at least since 

 1868, it was only in 1873 that Wolff definitely stated that the fungus 

 causing it was the same as that on the rye — ^viz., Urocystis occulta 

 (Wallr.), Ilab. This was the first time it had been found on wheat, 

 although since then it has been found in India and Japan, and if the 

 fungus was the same on both, then they ought to be mutually 

 infective. Since this smut had never been met with on rye in Aus- 

 tralia, I obtained material direct from the rye: in Germany. In one 

 experiment 200 grains of wheat were dusted with the spores of flag 

 smut of wdieat obtained from the crop of the previous year, and 

 200 grains of rye were dusted with similar spores. They were sown 

 alongside each other on 28th June, and examined when thoroughly 

 ripe on 29th December. Of the wheat 190 grains genninated, and 

 of the plants produced twenty-one were affected with flag smut, or 

 11 per cent. Of the lye 186 grains germinated, but the plants were 

 absolutely clean. The same variety of wheat (Federation) and lye 

 were also sown, without the seed being infected, and the plants were 

 entirely free from flag smut. 



Another experiment was carried out in which there were six plots 

 of twenty grains each, and wheat and rye were cross-inf(X)ted. The 

 ordinary seed of wheat and rye were sown. Then, seed wheat in- 

 fested with the spores of flag smut from wheat, and another lot with 



