FUNGOID PESTS OF CULTIVATED PLANTS. 23 



PESTS OF VIOLET AND PANSY. 



Considerable anxiety is manifested by those who grow these plants 

 extensively as to the prospects of the future, with the increasing number 

 of Violet diseases which we are about to enumerate. Nevertheless it 

 must still be remembered that quite a number of fungoid pests are known 

 as affecting this family which have not yet made their appearance in the 

 garden, but are common on uncultivated representatives. To be fore- 

 warned is to be forearmed, and all prospect of contagion from infested 

 wild plants should always be held in consideration. For this purpose we 

 have thought it prudent to give incidental notices of the diseases to 

 which uncultivated plants are liable, as well as some affecting cultivated 

 species, which have not as yet invaded our shores. 



VIOLET LEAF-SPOT. 

 Phyllosticta Viola (Desm.), Plate I. fig. 17. 



This spot has occurred on the leaves of Viola odorata and Viola 

 tricolor in various parts of Europe. It disfigures the foliage, but seems 

 to have but little influence on the flowering. 



White rounded spots are formed on both surfaces of the leaves, 

 several spots occurring on the same leaf, and then occasionally coalescing 

 and forming irregular blotches, but with a definite margin. The 

 receptacles, or perithecia, are very minute, resembling little black dots 

 just visible to the naked eye, scattered over and immersed in the 

 bleached spots. 



The sporules, or conidia, are produced within these receptacles, 

 escaping when mature by a pore at the apex. In this instance they are 

 cylindrical and straight (10 /u long), rounded at the ends and colourless, 

 oozing from the mouth of the receptacle in the form of a whitish 

 tendril. 



The variety on the Pansy has rather smaller sporules (7 X 3 p). 



This pest is known in France, Belgium, Italy, and Great Britain, as 

 well as in Australia. 



If troublesome in gardens fungicides should be resorted to in order 

 to prevent spreading. 



Sacc. Syll. iii. 203 ; Cooke Hdbk. No. 1352 ; Grevillea, xiv. 73, 

 No. 404. 



Another species, Phyllosticta Liberia (Sacc.), with blackish leaf-spots 

 and very minute sporules, occurs on Sweet Violet leaves in France and 

 Belgium. 



Ascochyta Violw (Sacc.) has -badly attacked Violets in this country. 

 See Gard. Chron. Nov. 5, 1904, p. 328. 



DOG VIOLET LEAF-SPOT. 

 Septoria Viola (West.), PL I. fig. 18. 



This minute endophyte has occurred upon the leaves of several 

 species of Viola, and especially on the Dog Violet, V. canina and V. 

 sylvestris, probably also on the Sweet Violet. 



Pale bleached spots are formed on the leaves, circumscribed by a 



