2^6 Minnesota Plant Diseases. 



Trametes root-rot (Tramctes radiciperda Hartig.). This 

 root-inhabiting pore fungus has been very thoroughly investi- 

 gated in Europe where it has done an enormous amount of 

 damage to coniferous and broad-leaved forest trees. The myce- 

 lium of the fungus travels from root to root in the living trees 

 and the disease is thereby rapidly spread. It later passes from 

 the root into the stem, chiefly through the inner bark, and here 

 attacks the wood. The affected trees soon die and the wood 

 undergoes a red rot. The fruiting bodies are formed where 

 they may distribute their spores into the air and are therefore 

 usually above ground. They are irregular in shape varying ac- 

 cording to their position; they are brown above, have white 

 flesh, and the lower surface, upon which the pores are formed, 

 is also white. The fungus is not infrequently found on timber 

 in mines. 



European botanists recommend for the prevention of the 

 spread of this disease the isolation of the infected region by dig- 

 ging ditches deep enough to cut through all of the roots, there- 

 by preventing the spread of the mycelium by way of the roots. 

 In the isolated areas, fruiting bodies may develop either from 

 the exposed roots or from the standing trunks. To prevent the 

 spread of the disease by means of the spores so formed, the 

 roots should again be covered with soil and the trunks and 

 stumps burned. The formation of mature fruiting bodies 

 should be prevented. The extent of the distribution of the fun- 

 gus in Minnesota is as yet unknown. 



Ring scale of pine [Trametes pini (Brot.) Fr.~\. Ring scale 

 is a very common parasite on pines both in Europe and in this 

 country ; it is also known on Douglass fir. The fungus gains en- 

 trance to the tree usually through wounds or broken limbs, par- 

 ticularly the older branches, in the heart-wood of which no pro- 

 tection-coat of resin has been formed. After it has gained en- 

 trance to the stem, the mycelium grows in longitudinal stripes 

 above and below the points of entrance; in the same year's 

 growth and in successive years it works from the interior to the 

 exterior. In this way zones of the diseased regions are formed 

 exteriorly (ring scale). The wood attacked by the ring scale un- 

 dergoes a peculiar disintegration. There are formed in the de- 

 caying wood numerous small, isolated patches of the white my- 



