550 



JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



undoubtedly the presence of too much water in the soil for a time, even 

 if only for a short time, which reduces the vitality of the plant almost 

 at once. Overwatering must be avoided at all costs; indeed it would 

 probably be better not to water at all — provided the ground had been 

 thoroughly dug and a loose soil mulch was kept on the surface in dry 

 weather — than to overwater. Drainage must be thoroughly efficient. 

 Another cause of loss of vitality through root-weakening is the too 

 prevalent practice of placing thick layers of manure between the spits 

 in double-digging. Every care should be taken to incorporate the 

 manure used thoroughly with the soil, and to avoid separate layers of 

 soil and manure alternating with one another. Over-manuring- may. 

 result in yet another mode of check. 



Probably no one cause contributing to the weakening of the root, 

 and thus laying it open to attack by the fungus, will be found that 

 will fit all cases of disease, but there seems no doubt that if care be 

 taken to avoid every possible check to root development and activity, 

 the " streak disease " will cease to be so troublesome. 



