DISEASES OF CULTIVATED PLANTS 451 
TURNIP 
Black-Rot. The same bacterium attacks turnips as cabbage, cauliflower 
and other mustards; the diseased roots show blackening of the parts with final 
decay. 
Club-Root. This fungus organism (Plasmodiophora Brassicae Wor.) infests 
the roots of many cultivated mustard plants, including the turnip, radish, 
rutabaga, etc. The treatment is the same as stated under cabbage. 
Downy Mildew (Feronospora parasitica (Pers.) De By.) sometimes occurs 
attacking turnip plants. 
VERBENA ; 
Mildew. Cultivated verbenas are attacked by the mildew Zrysiphe 
Cichoracearum D C) which is socommon on the wild vervains. It is to be 
treated as other powdery mildews, by spraying with fungicides. 
VERONICA 
Leaf Diseases. Cultivated species of veronica are attacked by several leaf 
dise: ses. which have been imperfectly studied. Perhaps the most common of 
these is due to the typical leaf-spot fungus (Septoria veronicae (Rob). There 
are other parasitic species which attack the genus, including a downy mildew 
and a rust. 
VETCH 
Spot. <A spot disease (Protocoronospora nigricans Atk. and Edg.) has been 
described as new from New York. 
The Wilt of Vetch similar to that ofsoy beans, cow peas and cotton has also 
been described. 
VINCA 
Leaf-Spot. The large flowered’ vinca is occasionally disfigured by a leaf- 
spot (Sphaeropsis vincae Sacc.) which may also develop as a stem disease. It 
has not beed studied carefully with us. * 
VIOLET 
Leaf-Spot and Leaf Blight (Pryllosticta Violae Desm. and Cercospora Violae 
Sacc.) are sometimes prevalent, and with downy mildew of violet should yield 
to spraying with fungicides. 
Nematodes of violets are, on the other hand, not amenable to spray treat. 
ment. The parasite in the case is the same as named under cucumber 
nematodes, likewise its effects. Soil treatment will also be effective in 
prevention here. 
Root-Rot. Root-rot (Thielavia basicola Zopf.) has not been reported as 
troublesome by greenhousemen in Ohio, but it is scarcely possible it can be 
entirely lacking when the disease occurs upon tobacco and catalpa in fields. 
The blackening and rotting of the roots, due to the fungus, will impair the 
development of the plants and the flower growth seriously. It does not seem 
possible that anything short of sterilizing the soil and starting new plants will 
ckeck the root-rot where once established. 
VIRGINIA CREEPER 
Leaf-Spot. The leaves of virginia creeper are frequently curiously spotted 
by a leaf-spot fungus (Phyllosticta labruscae Thiim.) which gives dying spots with 
colored border. This leaf-spot is also very common upon the Japan creeper 
and is identical, according to recent reports, with the leaf-spot of the grape; 
indeed we have a large number of the well known diseases of the grape at- 
tacking the Virginia creeper. These include anthracnose, which may be 
distinct, the black-rot fungus, of which this Phyllosticta may be a stage and 
possibly others. This would be especially true in the vicinity of cultivated 
grape vines. ' 
