36 BULLETIIiT 797, TJ. S. DEPARTMENT OF AGRTCUT.TURE. 



Another trouble to be feared on hyacinths is the " old disease " of 

 the Netherlands. This also exhibit's itself in rings, but they are 

 dark. This also should be guarded against and culled out, as in 

 the case of the yellows. In the growing plant this disease shows 

 itself in the leaves in much the same way, but the water-soaked area 

 is much more easily distinguished by the darker discoloration of the 

 tissues of the leaf. This disease is caused by the eelworm {Tylenchus 

 dipsaci). The organism can be seen on an examination under a low- 

 power microscoj)e of a portion of the tissue from the edge of the 

 infestation macerated in water. The eelworm seen with the naked 

 eye, commonly present, is a very different thing, which should not 

 cause alarm. 



THE MOSAIC DISEASE. 



All the classes of bulbs treated in this bulletin are more or less 

 affected with the mosaic disease, which in all cases reduces the vitality 

 and stature of the plants. The Sir Watkin and Princeps Maximus 

 narcissi and, of course, the broken tulips exhibit the condition most. 

 Our work has demonstrated that this disease can be reduced if 

 not quite gotten out of narcissi by selection. It is well known 

 that it does not appear in seedlings. This is the " gray disease " 

 of the Netherlands. It is carefully culled out of both narcissi and 

 hyacinths, but when it comes to tulips the case is very different. 

 Here the breaking, as it is called, gives a very spectacular and com- 

 monly pleasing effect in the flowers that is greatly admired. Con- 

 sequently, nearly as long lists of broken tulips as of breeders have 

 been segregated and established as commercial varieties. Their use 

 and study are more extensive in the British Isles than elsewhere. 



It would probably be much wiser for the commercial grower in 

 this country not to attempt to plant these broken tulips, for a time 

 at least, or if he grows them to do so at a safe distance from the 

 breeders, which will always be the main stocks, for it has been re- 

 peatedly shown that tbis diseased condition is communicable. This 

 mosaic affection should be looked upon just as much as a disease in 

 tulips as it is in other well-known plants. There exists abundant 

 evidence of the communicability of this disease, and there are some 

 suggestions that the aphis may be the main carrier. 



THE BEST VARIETIES TO PLANT. 



While there might be substantial agreement among growers as to 

 the best varieties of hyacinths to plant, fewer would agree on lists 

 of narcissi, and it would be difficult to find two who would agree 

 on the same list of tulips. Any recommendations, therefore, of 

 tulip or narcissus varieties are subject to all sorts of revisions, but 

 may be useful to those who have had little or no experience with the 



