552 



How to Protect Wheat. 



[Sept. 



of the damage this minute organism can bring about it may be 

 noted that in 1916 it was responsible for the loss of 100 million 

 bushels in the three prairie provinces of Canada, and in the 

 United States of over 200 million bushels in North and 

 South Dakota, Montana, and Minnesota alone. Fortunately 

 for Britain, Black Rust of wheat is exceedingly rare in our 

 islands, and has been regarded as practically non-existent. 

 During the past few years, however, its occurrence in a certain 

 district in Pembrokeshire has been observed, and inquiry has 

 shown that the attack is of several years' standing and extends 

 over a wider area than was at first thought. A special survey 

 was commenced last autumn, conducted jointly by the Agricul- 

 tural Department of the University College at Aberystwyth and 

 the Ministry of Agriculture. From the results obtained by the 

 Survey it appears that Black Bust in severe form now occurs 

 annually over the whole of Pembrokeshire, Carmarthenshire and 

 South Cardiganshire. The disease is locally termed " blast," 

 and its appearance is often considered to be due to bad weather. 

 The damage caused has been very severe. The fungus particu- 

 larly attacks the straw, which it often completely cripples, and 

 on which the black streaks of spore-masses develop. Losses 

 of over 50 per cent, are frequent, and in some cases the entire 

 crop is mined and is not worth threshing. Not a few farmers 

 in South Pembrokeshire have entirely abandoned wheat growing. 



Although south-west Wales is mountainous and not a wheat 

 growing country, the amount grown is highly commendable and 

 is a material contribution to the nation's supply. The figures 

 for 1919 are: — Cardiganshire, 7.208 acres: Carmarthenshire, 

 11,421 acres; Pembrokeshire. 8.484 acres. If proper measures 

 be taken the yield from these 22.000 acres may probably be doubled. 



The Barberry Menace. — Unlike Yellow Bust. Black Bust 

 has a second host-plant, namely, the common Barberry, on 

 which it occurs very widely. The injurious effect of Bar- 

 berry on wheat has been known to farmers for upwards 

 of two centuries. They affirmed, in spite of opposition, 

 that it led to attacks of Black Bust, and subsequent 

 investigation showed that they were right, the scientific 

 proof and explanation being obtained many years later. The 

 survey in Wales shows that the Barberry is generally and 

 plentifully distributed in the three counties mentioned, occurring 

 around the homestead and in the hedges. The fungus is found 

 on the Barberry leaves in the spring in the form known as the 

 "cluster-cup." Stretches- of Barberry 100 yards long have 

 been noted in lanes and on the roadside, sometimes covered 



