68 REPORT OF SCHIMMEL & Co. OCTOBER 1915. a 
on which is has occurred and the ground underneath them should be thoroughly 
drenched in winter with a sulphate of copper solution. The disease is called “rose 
leaf scorch’. “Rose black mildew” is rare; it is due to Peronospora sparsa, Berk. 
The fungi are only to be detected with the aid of a powerful lens. Its presence is 
evidenced by the sudden drooping of young vigorous leaves, and the shoot bearing 
them becomes limp and dies. Blackish or reddish stains will then be observed, and 
on these the mildew can be found by the aid of a lens. At present it seems to be 
confined to roses cultivated in greenhouses. 
Puccinia tanaceti, DC. forms brown spots of rust on the leaves of tansy and sun- 
flower. Bordeaux mixture sprayed over the plant has been found to check the disease. 
The tuberose has recently been attacked by Hypochnus filamentosus, Pat. (Hypoch- 
naceae), forming a mould on the surface of the leaves. It can be checked by a treat- 
ment with rose-coloured potassium permanganate solution, to which a little soft soap 
has been added. 
One of the diseases of the vanilla plant is caused by Calospora Vanillae, Massee : 
(Melanconidaceae). In the Seychelles it spread to such an extent that the whole: — 
industry was threatened, and it has also been reported from anes New Granada, 
Réunion and Mauritius. 
The violet is subject to several fungus diseases. Ascachyta Violae, Sacc. (Sphae- 
rioidaceae) causes large circular, yellowish or brown patches to appear on the leaves. 
These spots subsequently become yellowish-white, dry up and fall out, leaving holes. 
The leaves should be removed as soon as such spots appear. The disease causes 
much damage and occurs generally where an excess of moisture is present. Phyllosticta 
Violae, Desm. (Sphaerioidaceae) causes a similar disease. 
“Violet leaf spot”, due to Cercospora Violae, Sacc. (Dematiaceae), forms pale rond 
spots visible on both sides of the leaf. It sometimes becomes epidemic on plants 
grown in frames, when the plants are crowded, and the soil and atmosphere constantly 
damp. All leaves with pale spots should be removed, and the plants sprayed with 
Bordeaux mixture. Alternaria Violae, Dorsett (Dematiaceae) is widely spread in the 
United States and causes a most destructive disease. It attacks especially plants of 
rapid, succulent growth. It appears first as yellowish, semi-transparent spots on the 
leaves, these spots become blackish and fall out, leaving holes. Clusters of olive- 
coloured conidia appear on the spots and afterwards spread the disease. ‘Violet 
rust”, caused by Puccinia Violae, DC., occurs on wild as well as on cultivated violets. 
Spraying with potassium sulphide solution seems to check the disease. 
On the leaves of wormwood, a kind of rust caused by Puccinia Absinthtii, DC., forms 
small scattered or clustered yellowish or pale brown spots. The teleutospores form in 
the autumn scattered or clustered round blackish spots on both sides of the leaf and on 
the stem. Wormwood is attacked, besides, by Hrysiphe cichoracearum, DC. (Hrysibaceae), 
which also occurs on numerous other plants belonging to different natural orders. — 
In an additional article, Holmes deals with the application of the different fungicides. 
As to Origanum Bevani nov. spec., see p. 29. 
Phyto-physiological Notes. 
The formation of benzaldehyde by tyrosinase. 5 
If tyrosinase, an oxidase occurring in various plants, e. g. in some fungi, acts on ~ 
phenyl glycocoll in the presence of cresol, a strong smell of benzaldehyde becomes 
