FUNGOID PESTS OF CULTIVATED PLANTS. 187 



Berberidis of Thiimen is not fully determined. If so, the conidia are 

 reported to be oval and rather small (7-8 X 3-3^ /u). 



Succeeding this stage the globose receptacles appear on the surface of 

 the mycelium, dotted about like little black points. Each receptacle is 

 surrounded by a circle of about ten appendages, the apex of each twice or 

 more forked, the branches spreading, with the tips obtuse. Each receptacle 

 encloses about six asci, and each contains from six to eight sporidia. 



This mildew is recorded for Britain, France, Belgium, Germany, Fin- 

 land, and Italy. 



Should it be required, the sulphur remedy is applicable. 



Sacc. Syll. i. 47 ; Cooke, M. F. p. 219 ; Cooke, Hdbk. No. 1921. 



BERBERRY CLUSTER-CUPS. 

 Mcidium Berberidis (Gmel.), PL XVII. fig. 23. 



These cluster-cups have the merit of being historical, since it is over 

 them that the battle has been fought which has sought to establish the 

 theory that cluster-cups may be produced on one species of plant, such 

 as the leaves of the Berberry, while the uredospores and teleutospores 

 belonging to the same cycle may be produced upon quite a different 

 species of plant, such as the leaves of Wheat. We have no cause to 

 espouse or reject that theory here, since we have only to regard the 

 cluster-cups as a disease of the Berberry shrub, and leave the diseases of 

 the Wheat plant to take care of themselves. 



It is in the spring that the leaves of Berberis vulgaris exhibit the 

 thickened discoloured spots (2-5 mm. broad), which ultimately are fissured 

 to allow of the extrusion of the cluster-cups, such spots being somewhat 

 orbicular and convex. The cluster-cups are rather elongated and closely 

 packed side by side upon the spots. The margin of the cups is white, 

 spreading, and toothed. The secidiospores are produced in chains from 

 the base towards the apex of the cup, and are somewhat globose, becoming 

 angular by compression (14-26 /*), with a smooth surface, and of an 

 orange colour. 



Spermogonia are produced in small clusters on honey-coloured spots, 

 and are supposed to have some influence in the cycle of which they are 

 believed to form a part. With the spermogonia and the cluster-cups the 

 story, in so far as the Berberry is concerned, comes to an end. 



They are produced on the leaves and fruits of several species of 

 Berberis, and on Mahonia. 



This fungus is reported for the greater part of Europe, North 

 America, Asiatic Siberia, and uncertainly for parts of the Southern 

 Hemisphere. 



Certain theorists are at war with the Berberry bush on account of the 

 Wheat mildew, and, whether with JEcidium or not, cry aloud for its 

 extirpation. 



Sacc. Syll. vii. 2191 ; Cooke, Hdbk. No. 1612 ; Cooke, M.F. 195, t. 1, 

 f. 7-9 ; Mass. PL Dis, p. 247 ; Smith, Field Crops, p. 159, figs. 82 to 88 ; 

 Plowr. Brit. Ured. 163. 



