LEAF AND SEEDLING DISEASES 171 



it is recommended that they should be underj^lanted with 

 beech, after sufficient thinning has bfeen made to enable 

 the beech to grow. As the beech is deciduous, the diseased 

 needles fall through it and winter on the ground. In the 

 follo\Wng spring the young beech foliage acts as a screen, 

 which prevents the free circulation of the ascospores to the 

 larch above. This treatment has proved verj* effective in 

 some woods at Freising near Munich. 



Meria lariois {VuUUmin). This is another fungus which 

 causes the browTiing and fall of the needles. The disea.se 

 was first described by £mile Mer (1895), who noted it in 

 1890 in a nursery near Xancy. The attacked plants were 

 two or three years old, and in June many of the leaves, 

 especially on the lower branches, turned yellow. Later the 

 vellow colour slowlv gave wav to brown, beginning at the 

 tip. The disease spreads all through the summer and 

 attacked leaves may fall as early as July, though they 

 generally remain attached to the trees until within one or 

 two months of the normal leaf-fall. This disease is par- 

 ticularly frequent in nurseries, but may be found in planta- 

 tions, especially on small trees 6 to 10 ft. high. Such trees 

 are generally attacked on their lower branches, and the 

 comparative immunity of larger trees is probably due to 

 their branches being too far from the ground to be attacked 

 by the conidia. 



The fungus was worked out by Vuillemin (1896), who 

 created the new genus Meria to receive this single species. 

 Together with H ypo'itoynum Fliddanum (another new fungus, 

 which he described, on the needles of Pinus austriaca and 

 P. montana) he placed Meria laricis in a new family, the 

 Hypostomaceae, which he considers to be closely related to 

 the L'stilagineae, or smuts. The hyphae which grow in the 

 larch needles are septate, branched, and have mucilaginous 

 sheaths. Conidiophores, which arise verj* soon after infec- 

 tion, grow from mycelial ma.sses just inside the stomata, 

 and emerging through the stomatal pores, divide bj* three 

 septa into four segments. Each .segment bears a single 

 sterigma, at the end of which a colourless conidium is 

 developed, 8-10 / 2-6-2-7 ix. This conidiophore closely 



