332 



BULLETIN No. 189 



RADISH, Raphanus sativus 



\June, 



Damping-off of radish seedlings by R. Solani has appeared sev- 

 eral times in the floricultural greenhouses. During May, 1914, an at- 

 tack of Rhizoctonia on mature radishes was observed in the writer's 

 home garden. The first sign of the disease was the yellowing of the 

 foliage, followed by the wilting of the leaves. On pulling up a 

 plant, the crown was found to be rotted at the base of the leaves. The 

 rot progressed slowly and killed only a few of the plants. After it 

 had proceeded for some length, the radishes cracked farther down. 

 This is very characteristic of the disease at this stage (Fig. 16). 



In 1895 the damping-off of radish seedlings by a sterile fungus, 

 which was later identified as Rhizoctonia, was first reported by Atkin- 

 son. 4 Duggar and Stewart 32 in 1901 noted a disease caused by Rhi- 

 zoctonia of mature radishes forced in a greenhouse. The disease 

 caused a soft rot of the crown or lesions in this region. The leaves 

 were generally unaffected until a large part of the root had decayed. 

 Plants in all stages of growth were affected and killed. Duggar and 

 Stewart also found a Rhizoctonia in connection with the damping-off 

 of radish seedlings in the greenhouse. 



FIG. 16. LATE STAGE OF KOOT ROT OF RADISHES CAUSED BY Rhizoctonia Solani 



