FUNGOID PESTS OF CULTIVATED PLANTS. 191 



margin. The receptacles are scattered over the spots on the upper 

 surface. Sporules cylindrical, or rod-like, curved (35-40 x 2-2J p), with 

 two to four obscure septa, expelled when mature in whitish tendrils. 



It is common in Western Europe. 



Sacc. Syll. Hi. 2652 ; Grevillea, xiii. 76 ; Cooke, Hdbk. No. 1312. 



DOGWOOD MILDEW. 

 Erysiphe tortilis (Wallr.), PL XVIII. fig. 31. 



The powdery mildew of the Dogwood is by no means an uncommon 

 infliction, the thin white mycelium entirely overspreading the leaves, with 

 an evanescent coating. The conidia are first produced as in other species, 

 and these are followed, later on, by the small globose receptacles, which 

 are scattered over the mycelium. The appendages are very long, and even 

 ten times as long as the diameter of the receptacles, but neither branched 

 nor divided at the apex. The number of asci in each conceptacle is four, 

 and each encloses four sporidia. 



This mildew is recorded for France, Belgium, Germany, and Italy. 



May be checked by the application of powdered sulphur. 



Sacc. Syll. i. 65 ; Cooke, Hdbk. No. 1929 ; Cooke, M. F. f . 245, 246. 



LILAC LEAF-MOULD. 

 Ovularia Syringa (Berk.), PI. XVIII. fig. 32. 



This white mould on lilac leaves was first observed by Berkeley in 

 1881. The flocci are for the most part decumbent, surmounted by the 

 simple canidia, which are at first subglobose, with a terminal wart or 

 papilla ; at length they become elliptic and then ovate, being very large 

 for such a mould (50-70 /z long). 



It was discovered in Scotland, but is very little known, and has never 

 come under our observation. 



Sprinkle with Bordeaux mixture. 



Sacc. Syll. iv. 747 ; Gard. Chron. 1881, fig. 135 ; Grevillea, 1882, 

 x. 115, xi. 15. 



A black mould (Cercospora lilacis), of a destructive character, is 

 known in France, Belgium, Austria, and Italy, but at present has not 

 been recognised in Britain. It forms grey or reddish oblong spots, and 

 has pointed septate olive conidia (15-25 p long). 



LILAC LEAF- SPOT. 



Phyllosticta Syringes (West). 



One of the most common causes of the spotting of Lilac leaves is the 

 above-named parasite, which forms broad bleached spots of an irregular 

 form, with a brownish margin. The receptacles are seated on the upper 

 surface of the spots, and are minute and dot-like. The sporules are 

 oblong (8 x3/x), with two guttules, and uncoloured. 



It is known in France, Belgium, Portugal, and Italy. 



Sacc. Syll. iii. 109 ; Grevillea, xiv. 72. 



