66 DISEASES OF GLASSHOUSE PLANTS 
shrivel up and may break, causing the plant to fall over. 
At times the lesions appear higher upon the stem, and the 
entire shoot and blossoms may be affected. The brown 
rot spreads deep into the tissues, both above and below 
ground (Fig. 10). Rosenbaum states that in one case 40 
per cent of the plants on a nursery were affected, which 
indicates that the disease may at times be a serious one. 
The Causal Organism.—acrosporium solani was first 
described in 1882 as causing an early blight of potatoes, 
and since then has been recorded on many plants. The 
fungal hyphe vary from light brown to an olive colour, 
and produce characteristic brown septate spores. 
The disease has not yet been reported in England. 
Verticillium Collar Rot.—Pritchard and Porte (38) 
have described a collar rot of tomato seedlings caused 
by anew species of Verticilliwm to which they have applied 
the name V. lycopersict. Dark brown lesions, similar to 
those produced by Macrosporium solani, appear girdling 
the stem, mainly at the soil level. These enlarge and the 
tissues become weak and brittle; but, unlike the Macro- 
sporium disease, there is very little infection of the roots. 
The authors found that diseased plants were readily 
snapped off by the wind, and while some recovered by 
forming a callus over the wound, these individuals were 
seldom as productive as healthy plants. The disease is 
chiefly one of the seed-bed, where the tender nature of 
the plants renders them highly susceptible. 
The fungus produces a similar disease of the potato 
and horse nettle—Solanum carolinense L. As the disease 
is typically one of the seed-box, sterilizing the propagating 
soil is recommended as a means of control. Susceptible 
hosts should not be allowed to grow in infected areas, as 
these assist in the spread of the disease. 
CROWN CANKER OF THE ROSE 
This disease is commonly found under glass, and while 
the percentage of plants actually killed is small, there is 
