1920.] 



How to Protect Wheat. 



553 



with the " cluster-cups " of Black Rust, from which spores were 

 being discharged and blown in all directions. In another strik- 

 ing case a piece of Barberry hedge adjoined a wheat field, and 

 the golden spores were being rained from the cluster-cups 

 over very promising wheat. Isolated bushes of Barberry occur 

 in other parts of England and Wales, but not to anything like 

 the same extent.* The explanation of these severe attacks of 

 Black Rust in the south-west of Wales is therefore clear; they 

 are largely, if not entirely, due to the presence of Barberry. A 

 full and illustrated account of this outbreak will be published 

 shortly in the Ministry's Journal, but the present opportunity 

 is taken of pointing out the danger so that every effort may be 

 made to exterminate the shrub. 



Although other factors may be concerned, there can be no 

 question that the Barberry is the offender. The same shrub 

 accounts for the enormous losses in the United States and 

 Canada. A native of Europe and Asia, it has been planted in 

 gardens in America and is now found wild along streams, rivers 

 and roadsides. During the past few years the clearest evidence 

 against the Barberry has been obtained in the Northern States. 

 Each bush may commence a local outbreak, which serves as a 

 centre from which the disease may, by means of its summer 

 spores, spread for manv miles. With a view to preserving the 

 wheat crop an energetic Barberry campaign is now being carried 

 out in Canada and in the United States. Similar campaigns 

 have taken place in Europe. In Denmark, for instance, owing 

 to the ravages of Black Rust, a law was passed in 1903 making 

 the destruction of Barberry compulsory. From that date the 

 disease commenced to die out, and is now practically non- 

 existent. 



No variety of wheat, suitable for use in Wales, can be recom- 

 mended at present as immune to Black Rust. With a view 

 to discovering whether any such wheat exists, over 70 varieties 

 are being tested this season in Pembrokeshire and Cardigan- 

 shire. In the meantime attention should be concentrated on 

 the Barberry. It should be rooted up, not merely cut down, 

 wherever it occurs. Such a large number of bushes occur in 

 the area that a determined and concentrated effort is needed. 

 Every bush destroyed means a handicap on the spread of the 

 fungus, and by energetic attack there is no reason why the 

 fungus should not be eradicated, and as a result greatly increased 

 wheat crops be secured. 



* It should be noted that the Barberry which takes the Black Rust is the 

 common or European Barberry, licrhrris ru/</ar/s. So far as is known, B. Daricinii, 

 B. stcnophylla and many other garden species do not become rusted. 



