184 
Journal of Agricultural Research 
Vol. XXI, No.3 
SUMMARY 
Collar-rot of tomatoes has been prevalent in Maryland, New Jersey, 
and Delaware during the three seasons 1917, 1918, and 1919, destroying 
many seedlings in the seed bed and newly set plants in the fields. 
The girdling of the stem at the surface of the ground characteristic 
of the disease may be produced by three fungi, Verticillium lycopersici , 
Macrosporium solani, and Rhizoctonia solani. 
In inoculation experiments with these fungi, made either by applying 
fresh cultures to uninjured stems or by mixing them with the potted soil, 
Verticillium lycopersici and Macrosporium solani infected tomato seed¬ 
lings about equally well, causing typical lesions on 65 to 100 per cent of 
the plants used, while Rhizoctonia produced a very few infections of a 
superficial nature. 
On stems of potato and horse nettle all three fungi produced typical 
collar-rot lesions, but the percentage of infections was much higher for 
Verticillium lycopersici and Macrosporium solani than for Rhizoctonia 
solani 
