242 NEBRASKA STATE HORTICULTURAL SOCIETY. 



opinioti that this last type of root rot is induced primarily by either 

 unfavorable soil or climatic factors, or both, which so lower the tone 

 and vigor of the plants that various saprophytic forms come in and 

 complete the work of destruction. Some of our fruit trees, such as 

 the cherry and apple, and also forest and shade trees, are attacked by 

 root-rotting fungi. The wood of root and even the crown is slowly 

 disintegrated, and the mechanical structures are so weakened that severe 

 storms may cause the affected tree to be blown over. White strands of 

 fibrils, the vegetative body of the fungus, may sometimes be seen upon 

 the fractured surface. In other cases the affected tree may remain 

 standing until it finally succumbs to the attack. 



Modified stems like tubers, rhizomes, bulbs or corms which serve as 

 storage organs for reserve food, suffer in many cases from rot-producing 

 fungi or bacteria. These storage organs are affected in much the same 

 way as the fleshy roots, but dry rots are not uncommon. The potato 

 is affected by several diseases in which a soft rot of the tubers is a 

 marked symptom. This is true in the disease known as the late blight, 

 a fungus disease, and also in the bacterial blights, while in some cases 

 a soft rot may result when the tops are not affected. In the dry rot 

 of the potato the fibro-vascular ring often shows a conspicuous darken- 

 ing when the tubers are cut across, and the badly rotted portions become 

 shrunken and darkened and more or less corroded. Diseases of this 

 kind may be spread by planting affected seed. Iris rhizomes, canna 

 rootstocks, hyacinth or calla lily bulbs, onions and similar modified 

 storage organs are often affected by organisms which produce soft rots. 



An immense amount of loss is caused in standing timber and in 

 fruit trees from dry rots of the trunk due to wood-destroying fungi 

 which gain an entrance through wounds or otherwise. It frequently 

 happens that the trunk of a tree is thoroughly permeated by the vege- 

 tative hyphae of the fungus before any external evidences of its presence 

 can be detected. These wood-destroying fungi may give rise to external 

 fruiting bodies, either loadstool-like or bracket sporophores, when they 

 have reached a sufficient vigor of growth. The affected wood is gradually 

 disintegrated by the work of the fungus which digests the woody ele- 

 ments. It is thus transformed into a brittle or even punky condition 

 that renders it unfit for the purposes which it must serve as a functional 

 part of the tree, and lessens or destroys the value of the wood for 

 lumber. Wood affected by dry rot is often discolored, sometimes show- 

 ing a marked blue, pink, yellow or reddish-brown coloration. Black 

 lines may often be noticed crossing irregularly through the wood or 

 surrounding definite areas. The vegative body of the fungus is frequently 

 invisible to the naked eye, but in some cases it shows as fine strands 

 or ropes, or even lamellae that run between the wood fibers or along 

 the silver grain. 



In a few cases buds are affected by rot-producing fungi. One of 

 the best examples of this effect is in the bud rot of the carnation. In 



