160 



sequent to the rules adopted by the International Congress in Brussels 

 1910. Of the distribution of the single species it may almost only be 

 said that they are common all over the country where their host-plants 

 occur. They always occur in greater abundance late in summer and in 

 autumn. The ascigerous fructification and the conidia are often asso- 

 ciated and the relation of both stages is so evident for most species 

 that I have simply stated the name of the conidial fructification as 

 synonymous under the chief species. On a few host-plants, however, 

 forms of Oidium will occur whose corresponding ascigerous fructifica- 

 tion has not yet been found, therefore they have been stated after- 

 wards as an appendix. 



The separate species of Erysiphaceae are, according to investigations 

 of Neger, Salmon, Marchal etc., said to be devided into several bio- 

 logical subspecies. Lit: E. 6. P. '", Neger 05 b, Lindau 08 "^ Salmon 00. 



Sphaerotheca. 



5%. Sphaerotheca tnacularis (Fries) ! , Syn : Erysiphe mac. Fries 



5. M. Ill "^ Sphaerot. castagnei Lev., Syll. I ^ Sphaerot. humuli (de 

 Cand.) Burrill, Salmon 00 ^^ Mucor erysiphe L.; MuUer 1767 2'^ Sphae- 

 rot. epilobii (de Cand.) de By., Syll. I ^ Oidium epilobii (Cda.) Sacc, 

 Syll. IV ^^ Oid. fragariae Harz, Syll. X'^", Humlens Meldug(R 02 a "^^ 



6. 04 a "'). 



Humulus lupulus, Euphorbia dulcis, Spiraea venusta, Filipendula hexapetala 

 S. ulmaria, Argentina anserina, Potentilla procumbens, reptans &. erecta. Coma- 

 rum palustre, Geum urbanum &. rivale, Alchimilla vulgaris & arvensis, Fragaria 

 cult, (see Salmon 01), Epilobium roseum, montanum, palustre, parviflorum & 

 hirsutum. 



597. Sphaeroteca fuliginea (Fries) ! , Syn : Erysiphe fuliginea Fries 



5. M. IIP5», Sphaer. hum. var. fuhginea (Schlecht.) Salmon 00"=. 

 Impatiens nolitangere, Odontites rubra, Euphrasia spp., Melampyrum vulgatum 



6. silvaticum, Alectorolophus major, Veronica longifolia. Arnica montana, Gene- 

 cio Jacobaea, Bidens cernuus, Crepis paludosa. Taraxacum spp., Leontodon 

 3utumnalis. 



598. Sphaerotheca mors uvae (Schweinitz) Berk. &. Curt., Syll. 

 I ^ Stikkelsbaerdraeberen (R 05 e ^*^), Amerikansk Stikkelsbaermeldug, 

 Lit: R 04 d, 04 e, 06 b, F. K. R. 07 b, Lind 6. Ravn 08 6. 10 "", Lind 10 k. 



This pest is imported to Europe from the United States. Massee 

 recorded its first appearance into Irland in the Gardeners Chronicle 

 Aug. 25. 1900. 



It was imported to Denmark in the following year and has later 

 on spread very much. The conidial stage is found in May to Novem- 

 ber; ripe ascigerous fructification has been observed in March. 



Very common on Ribes grossularia, rare on Ribes rubrum, nigrum 6~. alpinum. 



