1921.] Barberry and the Black Bust of Wheat 110 



were found 25 bushes, and 68 yd. of barberry hedge — 30 pos- 

 sible centres of infection, extending over 12 parishes. Pembroke- 

 shire has not been systematically worked, but barberry is known 

 to exist in 14 parishes. At one place there is a stretch of barberry 

 hedge over 100 yd. long, and at another about 70 yd. long. 

 These were the largest stretches met with, and it is a long time 

 since wheat was grown near them. It is clear that if the survey 

 were continued a very great deal more barberry would be 

 discovered. 



Extent of Black Rust on Wheat. — Time would not allow of 

 justice being done to this part of the work, and in many places 

 where barberry was found it was impossible to examine the 

 wheat growing in the neighbourhood. However, 45 cases wert 

 observed in Carmarthenshire. 15 in South Cardiganshire and 14 

 in Pembrokeshire. In each of these cases, moreover, barberry 

 was found in the immediate vicinity. From conversations with 

 farmers there can be no doubt that the disease has long been 

 prevalent over the greater part of the three counties. 



Results of Personal Interviews. — It has been said that the 

 farmers of a generation ago were aware that the common bar- 

 berry caused the black rust of wheat. This, however, cannot 

 be said of the present-day farmer in the surveyed district. To 

 him the life-cycle of the fungus is a mystery and the disease is 

 known to most of the farmers under the name of " blast "* and 

 is regarded, as are most other diseases, as entirely due to wet 

 weather. This idea is very deep rooted, and the fact that the 

 life -history of Puccinia graminis seemed to many like a fairy tale, 

 made it very difficult to convince them as to the true nature 

 of the disease. Consequently, the way in which the information 

 and advice given was received by the farmers depended chiefly 

 upon the educational attainments of each individual, the quantity 

 and position of the barberry and the condition of the wheat. 

 Very few farmers, who had the black rust affecting their wheat, 

 acted upon the advice given and removed the barberry at once, 

 but every farmer who had barberry on his land admitted that 

 he could never obtain a good crop of wheat when it was grown 

 near the bush. The popular variety of wheat is " Hen Gymro 

 (Old Welshman) which is particularly susceptible to the black 

 rust. 



* Local terminology in respect to plant diseases is very indefinite and 

 confused. u Blast" is applied to all rust diseases of cereals ; "blight" and 

 •'Mast" to the Phytophthoni disease of potatoes and "Might" to Woolly 

 Aphis on apple trees. The term "duon" (blacks) is also used in South Wales 

 to designate black diseases of cereals such as rust, but more especially smut, 

 while in North Wales bunt and smut are both known GIG penddu (blacklioad). 



