210 FUNGOID PESTS OF CULTIVATED PLANTS. 



Lime-tree Sooty Mould. 

 Fumago vagans (Pers.), PI. XIV. tig. 21. 



The leaves of the Lime are often blackened with this ,( sooty mould," 

 which sometimes quite encrusts the leaves. It also occurs, but less 

 commonly or profusely, on Oak, Elm, Birch, Willow, and other deciduous 

 trees. It is commonly preceded by honey-dew, upon which the mould 

 thrives and nourishes apace. 



The mould consists of brown creeping hyphjv, which are branched or 

 fasciculate, sometimes confluent and forming cellulose ganglia, constituting 

 a thin membranaceous stratum, of a blackish colour. The fertile threads 

 are short, ascending, and branched in the upper portion. Conidia terminal, 

 forming short chains, for the most part two-celled, rarely one-celled, or 

 three-celled (from 5-15 /* long), brown. 



Doubtless a state or condition of more complex fungi, such as 

 Capnodium. 



Causes injury by closing the pores or stomataof the leaves, but usually 

 so universal over all the foliage as to defy remedy. 



Sacc. Syll. iv. 2618 ; Berk, db Desm. Journ. Hort. Soc. iv. 251. 



Lime-tree Leaf-spot. 

 Septoria Tillce (West.), PI. XX. fig. 28. 



Perithecia on both surfaces of the leaves, seated on tawny spots, 

 which become pallid in the centre. Sporules straight or curved, 3-4 

 septate (35-40 x2-2^<, or sometimes longer). 



Known also in Belgium, Italy, and Austria. 



Sacc. Syll. iii. 2562 ; Grevillea, xiv. p. 76, No. 466. 



Alder Leaf-spot. 

 Septoria alnicola (Cooke), PI. XX. fig. 29. 



This parasite was first found in Britain on living Alder leaves, and 

 afterwards in Italy. The spots are pallid, brown or tawny, roundish 

 (5-7 m.). The receptacles are minute, black, dot-like, scattered over the 

 spots. The sporules oblong, and straight or curved (about 20-26 x ;,' ft). 



Sacc. Syll. iii. 2735 ; Cooke, HdbJc. No. 1889 ; Seem. Journ. Hot. iv. 

 p. 97, I 28; Grevillea, xiv. 101, No. 188. 



This is supposed to be a different species from Septoria Alni and 

 Septoria alnigena, both of which are found on Alder leaves in Italy, but 

 it is doubtful whether at least one of them is not tlie same. 



Ai.i-i.i; -leak J'.i.u k Mm i.D. 

 Passah /•' bacilUgera (Fres.), PL XX. fig. 30. 



This mould occurs on living and languishing leaves of the Alder, 

 occupying the under surface, forming small olive tufts. The threads 

 simple, collected in bundles, ilexitous and obtuse, olive-coloured, septate, 

 often twisted and interwoven amongst themselves. Conidia produced at 



