448 OHIO EXPERIMENT STA 
is surrounded by a development of what appears to bea parasiticfungus, a spec- 
ies of Vermicularia. The black masses of the fungus are also visible extending 
down upon the root bases which are lighter in color. A similar abundance of 
Vermicularia has been noted on the dead stems of potato tops which have died 
from fusarium blight. : 
This collar disease is just now under study. We believe something can be 
accomplished by spraying with Bordeaux mixture about the base of the plants. 
Certainly good will come by withholding excess water. This case of disease 
was described where fusarium blight and mosaic disease also prevailed. The 
fern-like leaf development is ascribed to the presence of the mosaic disease. The 
association of the two diseases may be casual. 
Leaf Mold (Cladosporium (?) fulvum Cooke) is a common trouble in tomato 
forcing-houses in the fall or near the close of the season. It produces spots in the 
leaves, while beneath they are covered by the grayish-brown mold fungus. The 
fungicides heretofore recommended for use in the greenhouse are available for 
the tomato leaf mold. 
‘Leaf-Spot or Leaf-Blight is an 
outdoor trouble, as is anthrac- 
nose. The leaf-spot fungus (Sep- 
toria Lycopersici Speg.) appears 
to be gradually traveling west- 
ward from the Atlantic coast, 
where it first appeared several 
years ago. During 1898 it was 
locally disastrous over the whole 
of Ohio, and again during 1900 
and 1909. It may be successfully 
prevented by about three thor- 
ough sprayings with Bordeaux 
mixture, though some difficulty 
attaches to the treatment of un- 
staked tomato plants in the field. 
(Bulletins 73, 89, 105). 
Mosaic disease attacks the to- 
mato under conditions similar to 
those giving trouble to cucumb- 
ers, tobacco, etc. It is believed we 
have a mosaic disease analogous 
to that in tobacco and that the Fig. 97. Tomato leaflet and stem attacked by leaf- 
spot. This causes dying of the leaves in showery seasons 
remedy is pointed out by the 
fact that the disease may be transmitted by touching first diseased and then 
healthy plants. 
The symptoms of the ordinary type of the disease are the alternation of 
darker green and yellowish-green color in the leaves; this makes the plants con- 
spicuous under ordinary circumstances. In 1909 with cases under glass, where 
the collar disease appeared to be associated, abnormal leaf forms were observed 
without very apparent intermixing of yellow areas in the leaves. The actual 
leaf forms suggested the name of fern-leaf trouble. In these specimens the 
internodes of the plants, the stems of the compound leaves and the petioles of 
the leaflets were all elongated; the leaf-blades were narrowed at times to mere 
borders along the mid-ribs. Gradations were also found between these extreme 
