FUNGOID PESTS OF FOREST TREES. 



385 



taining eight thread-like sporidia, which are curved and colourless 

 (60-90x14-3^). 



This also is known in France, Belgium, Germany, Sweden, Italy, and 

 Siberia. 



Sacc. Syll. vii. 3085 ; Cooke, Hdbk. No. 2278, fig. 357 ; Grev. Sc. 

 Crypt Fl, t. 118, fig. 2. 



Willow Mealy Mildew. 

 Uncinula adunca (Wallr.), PI. XXI. fig. 44. 



This mildew attacks the foliage of Willows, Poplars, and sometimes of 

 Birch, giving it the usual mealy or frosted appearance. The mycelium is 

 spreading, rather thin and white, giving rise to conidia of the Oidium 

 form, the joints of which fall away as they mature, and increase the mealy 

 appearance of the leaves. 



The conceptacles are globose and scattered or sometimes gregarious, 

 minute and dot-like, surrounded by a rather dense circle of appendages, 

 which are unbranched, and hooked at the apex. Each conceptacle 

 encloses from eight to twelve asci, containing four sporidia. 



Known throughout Europe, in Asiatic Siberia and North America. 



Sacc. Syll. i. 20; Cooke, M.F. t. xi. f. 221-224; Cooke, Hdbk. No. 

 1913. 



Conifee Seedling Disease. 

 Pestalozzia Hartigii (Tub.), PI. XXI. fig. 45. 



This disease is reported to destroy the seedlings of Spruce and Silver 

 Fir in immense numbers. The young plants lose their colour and die. 

 The bark just above the ground is destroyed, and exhibits the mycelium, 

 with the receptacles of this fungus which contain the conidia. 



The pustules are immersed, springing from a flattened stroma. The 

 conidia are extruded in black masses. They are at first colourless and 

 undivided, then oblong, with three transverse divisions. The two central 

 cells large, coloured, containing guttules, the terminal cells small and 

 colourless (18-20 ^ long), bearing at the apex from one to four slender 

 bristles (20 x1/j), and attached at the base to slender pedicels. 



The only remedy we have heard of is to remove and burn all diseased 

 seedlings. 



Mass. PL Dis. 297, 432 ; Hartig & Som. Bis. Trees, p. 136, figs. 76, 77. 

 The cortex of the Silver Fir is attacked by Plioma abietina in the 

 Bavarian forests and the Black Forest. 

 Hart. & Som. Dis. Trees, p. 138, fig. 79. 



Pine Clustek-cups. 

 Peridermium pini (Wallr.), PI. XXI. fig. 46. 



These peculiar cluster-cups are found on the leaves and young branches 

 of Pinus sylvestris, in about May and June. Those on the leaves differ 

 somewhat from those on the branches ; the former are scattered or in 

 small groups, and are cylindrical or compressed laterally. The mouth is 

 torn irregularly (2-2J mm. high). Those on the young twigs form swell- 

 ings, from the presence of the mycelium the cups are larger, crowded, 



