172 LEAF AND SEEDLING DISEASES 



resembles the promycelium of the rusts or smuts, and, as in 

 the latter group, it may give rise directly to hyphae, instead 

 of conidia, under suitable cultural conditions. Infection of 

 trees in the spring is brought about by conidia borne by 

 similar conidiophores on needles which have lain on the 

 ground during the winter. 



As a remedial measure Mer suggests picking off the dead 

 needles a short time before the normal leaf-fall in the 

 autumn. It is not impossible to treat nursery plants in 

 this way, as the diseased needles are readily detached by 

 drawing the hand along the branches. Needles which have 

 already fallen form small heaps on the ground, which can 

 be cleared up. 



This fungus is apparently the same as that described by 

 Hartig (1899) under the name of Allescheria lands (R. 

 Hartig) (=Hartigiella laricis, Lindau, in Engler and Prantl, 

 Die natiirlichen Pflanzenfamilien). According to Hartig, the 

 disease is common in Germany, and may attack the needles 

 of larch trees, especially in nurseries, as early in the season 

 as May and June. 



Hypodermella laricis (Tubeuf). This needle disease, which 

 was described by Tubeuf in 1895, is found chiefly in Bavaria 

 and the Tyrol, but has not, as far as I know, been reported 

 from elsewhere. When attacked by this fungus, some or 

 all of the needles of a dwarf shoot turn pale brown, but 

 remain attached to the tree. Entirely brown dwarf shoots 

 are often quite a conspicuous object on twigs whose needles 

 are otherwise green. Bright black apothecia appear on the 

 upper side of the needles, forming a single line of elongated 

 dots. The apothecia contain asci, which are about 1 10 ^ long 

 and contain four hyaline, unicellular, club-shaped spores, 

 66x6^, with a gelatinous membrane. Interspersed among 

 the asci, but shorter than these, are simple hyaline fila- 

 mentous paraphyses. The disease is found particularly on 

 the lower branches, and does not seriously interfere with 

 the growth of the trees. 



The larch needle-rusts. There are two genera of rusts 

 which grow on larch needles, both of which have been 

 found in Britain, though they are much more common on 



