122 
BRITISH GALLS 
Economic Notes 
Many gall-causing fungi are dreaded pests. The “ black 
scab” of Potatoes and Beet is caused by Oedomyces leproides 
Trb. Large nodulose fleshy tumours occur on the upper 
part of the root of the Beet and on the young tubers of the 
potato. 
Chrysophyctis endobiotica Sch. causes gall-like growths on the 
tubers and lower leaves of the Potato (see Journal of Board 
of Agriculture , ix., 1902, p. 320, paper by Professor Potter). 
Exoascus deformans attacks the leaves of Nectarine, Peach, 
and Almond. The leaves become greatly hypertrophied 
and distorted, and brightly tinted with red and purple. This 
disease is very common. Puccinia fabae causes thickened 
white spots on the seed-pods of Beans and Peas. 
The parasitic Rose canker Coniothyrium Fuchelii attacks 
cultivated as well as wild Roses, causing cankered over¬ 
growths on the stems. It apparently attacks Rubi also. 
Plate XXVI. depicts cankered stems of Rubus plicatus from 
Dungeness. 
An excellent illustration of a Bullace branch bearing what 
are popularly known as “ pocket plums ” or “bladder 
plums” may be seen in Plate XXV. This swollen and 
deformed condition of the fruit is caused by Exoascus pruni, 
a fungus which also attacks the Sloe, Wild Cherry, and 
cultivated Plums. The fruit of the fungus appears as a 
delicate whitish bloom in July. The fungus does not spread 
backwards on a branch, and may be kept in check by hard 
pruning. 
The researches of F. P. Brzezinski on “ Canker,” extend¬ 
ing over a period of seven years, indicate that the fungus 
Nectria ditissima , previously thought to be the cause of this 
disease, is only a saprophyte growing on dead tissue 
destroyed by other agents (see Comp. Rend., May 20, 1902). 
Probably, as remarked above, the canker is in most cases 
due to the presence of insects or of a bacterium. 
