PESTS OF THE FLOWER GARDEN. 



385 



Lavender Leaf-spot. 

 Septoria Lavandula (Desm.), PI. IV. fig. 77. 



Parasites of Labiate plants under cultivation as garden flowers are 

 very limited. It is now many years since we found Lavender plants 

 with a great number of the leaves attacked by this endophyte, which is 

 not uncommon in France, but which we have not met with again. 



The bleached spots are small on both surfaces of the leaves, mostly 

 rounded, but sometimes irregular, limited externally by a raised purple 

 line. They do not generally exceed one eighth of an inch in diameter, 

 but several spots are often seen on the same leaf. On the upper surface 

 of the spots a few black dots are to be discerned, which are the receptacles 

 or perithecia of the fungus. 



The sporules, or conidia, are long and thread-like, straight or curved, 

 and very narrow (25-35 x 2 //) ultimately ; when fully matured they are 

 expelled through a pore at the apex of the receptacle. 



This species has been found also in France, Italy, and Madeira. 



Sacc. Syll hi. 2914; Cooke Hdbk. No. 1340; Grevillea, xiv. 103, 

 No. 523. 



Lavender is also liable to a sickening disease, or "wilting," but the 

 cause has not been ascertained, and no fungus been found. 



PESTS OF THE SCROPHULARIACE.E. 



It is a singular fact that no important parasite has yet been recorded 

 in Britain for the numerous Scrophulariaceous plants in general cultiva- 

 tion, although many are known abroad. 



The destructive rot-moulds (Peronospora) are represented by at least 

 four species, which attack Antirrhinum, Digitalis, and Veronica, but only 

 Peronospora grisea has been met with on uncultivated Veronica, and 

 Peronospora sordida on Verbascum, in this country. 



The three diseases which produce leaf- spot on Mimulus, and the four 

 on Pentstemon, have, with one exception, never invaded our shores, 

 whilst Calceolaria is still unharmed, and therefore, on the whole, we 

 must be regarded as peculiarly fortunate. The exception is in the case 

 of Phyllosticta Pentastemonis {Grevillea, xiv. 90) which has produced leaf- 

 spot on one or two occasions in this country. There is also a leaf-spot 

 (Septoria Pentastemonis) with small round white spots on leaves of 

 Pentstemon, known in North America. 



A new fungus disease on Antirrhinum majus of the kind known in 

 America as Anthracnose, produced by Collet otrichwm Antirrhini (Stew.), 

 is recorded recently as causing elliptical or circular sunken spots on the 

 leaves of that plant in the United States (Joarn. B.H.S. vol. xxvi. 

 1901, p. 194). 



DISEASES OF ENDOGENOUS FLOWERING PLANTS. 



For the sake of reference we have kept these diseases together, as they 

 affect plants mostly of outdoor culture, reserving others, which require 

 warm houses or stove treatment, for separate notice hereafter, with other 



c 



