MOXILIA. 499 



Washing of stems with a sohition of iron sulphate in spring 

 before the buds unfold is suggested, also spraying of young 

 foliage with dilute Bordeaux mixture. 



Oidium. 



Mycelium epiphytic on living plants. Conidia unicellular 

 mid barrel-shaped, produced in chains on erect conidiophores. 

 Many have already been proved to be conidial forms of 

 Erysipheae. 



Oidium erysiphoides Fr. frequents living leaves of hop, 

 clover, cucumber, etc., and is probably the conidia of species 

 of J^i-tjsiphc on these hosts. (Britain and U.S. America.) 



0. Tuckeri Berk. On leaves and berries of the vine {see 

 Uncinuhi, p. 176). 



0. leucogonium Desm. On roses; probably the conidial form 

 of Splia.i roflirrii pannosa (see p. 172). 



0. farinosum Cooke. On living leaves of apple-trees. 

 (Britain.) 



0. chrysanthemi IJabh. On leaves of cultivated chrysan- 

 themum. (Britain.) 



0. aceris Babach. On leaves of Acer Pseudoplataaus. It is 

 probably the conidial stage of Uncimda hicornis. (Britain.) 



0. mespilinum Thiim. On leaves of medlar. (Britain.) 



0. destruens Peek. On Amdanchicr canadensis and Prunns 

 SI ri'fiiid m America. 



0. tabaci Thiim. On leaves of tobacco. 



0. monilioides Link, probably the conidial stage of Erysiphe 

 (jraminis, occurs on living grasses over the whole world (see p. 175). 



2. Sub-sect. Miicronemeae. 



Botrytis. 



Mycelium grey. Conidia more or less spherical, and pro- 

 duced in aggregations on the ends of branched conidiophores. 

 jVIany of the species are saprophytes, others are parasitic on 

 plants or insects, and others form sclerotia ; the latter have 

 already been considered under Sclerotinia (see p. 267). The 

 following are known to be parasitic on plants : 



Botrytis cinerea Pers. This enemy of many plants has already 

 been noticed as Sclerotinia Fuckcliana ; so also B. Dov.glasii Tubeuf. 



