248 FUNGOID PESTS OF CULTIVATED PLANTS. 



The best means of combat, which in this case is difficult to employ, is 

 to burn up the stems and roots so as to consume the resting spores. 



Sacc. Syll. vii. 841 ; Mass. B. F. p. 121 ; Cooke, Hdbk. No. 1783 ; 

 Cooke, M. F. p. 216. 



CLOVER BRAND. 

 Uromyces Trifolii (Hedw.), PI. XXIV. fig. 42. 



The foliage and stems of all the Clovers are liable to the attacks of this 

 parasite, which is unsparing in its work of destruction. All the stages 

 have been observed on the same kind of plant, although it is doubtful 

 whether the cluster-cups have been observed in this country. 



The uredo pustules are round or elliptical, and scattered ; after the 

 cuticle is ruptured the remains encircle the spores like a lacerated cup. 

 The uredospores are irregularly globose, or shortly elliptical (22-26 x!8- 

 20/i), of a brown colour, and minutely spinulose. 



The pustules of the teleutospores are smaller on the leaves, larger on 

 the petioles, and elongated, darker brown, and puffed out or bullate, for a 

 long time covered by the cuticle. Teleutospores ellipsoid, or almost globose 

 or pear-shaped, with the epispore or coating thickened at the apex, and 

 bearing a paler-coloured wart (20-35 x 15-22^), smooth brown, with a 

 deciduous peduncle. 



Known in France, Belgium, Germany, Holland, Switzerland, Finland, 

 Austria-Hungary, Italy, and North America. 



Sacc. Syll. vii. 1925 ; Cooke, M. F. p. 212 ; Ploivr. Brit. Ured. p. 124. 



Years ago we found on Clover a brand, mixed with uredospores, 

 which was two-celled (Puccinia fallens), but it has since been condemned 

 as a freak, since it would not " fit in " with a preconceived theory. 



CLOVER WHITE MOULD. 

 Ovularia exigua (Smith). 



This little white mould, which attacks Clover, was first described by 

 Worthington Smith, under the name Peronospora exigua ; but there is no 

 direct evidence that it is a rot mould of that genus, as there is no indica- 

 tion of resting spores, and the mode of attachment of the conidia is rather 

 that of Ovularia than Peronospora. 



This parasite appears as a minute white mould on the foliage of Clovers, 

 and is affirmed to cause putrescence. The fruiting threads of the mould 

 are frequently simple, but sometimes once or twice branched. The 

 conidia are terminal and lateral, being borne on minute lateral spicules. 

 The conidia are nearly globose, and borne singly, not in clusters, falling 

 off readily when mature, and of a very pale grey colour (8 x 6-7/u). These 

 conidia germinate from the side, but do not generate zoospores in their 

 interior. 



It may be inferred that the encroachments of this pest may be met, 

 more effectually than in the case of the true rot moulds, by fungicides, 

 such as Bordeaux mixture. 



Sacc. Syll. xi. 3841 ; Smith, Field Crops, p. 12, fig. 2. 



