FUNGI AS CONTRIBUTORY CAUSES OF WINDFALL 711 



sented. Since the study emphasizes fungous activity as a secondary 

 cause of windfall, special attention was given the diagnostic methods 

 for this determination. The first factor of importance is the rotting 

 of the roots. Either heart rot or sap rot found weakening the resist- 

 ance of the roots to the overthrow force of the wind is considered a 

 good indication of the cause of windfall. In connection with this, it 

 was found that almost invariably the root-rotted trees which were wind- 

 thrown showed the main infected roots to be broken off rather short 

 near the butt of the tree, and not pulled out entire with masses of earth 

 clinging to them, as in the case of sound-rooted windfalls. The proof 

 of the determination that fungi cause windfall is not always easily 

 determined in fungous infected stands, since many sound trees within 

 such an area are overthrown by the weight of falling trees or by the 

 loosening of the soil and root system through the uprooting of neigh- 

 boring trees. The windfall area studied on the Honeysuckle sale area 

 previously mentioned presents conditions which are capable of being 

 used in comparing the relative results of wind action upon two similar 

 portions of a stand," one infected with root and butt rot, the other hav- 

 ing but a slight amount of either. The portion of the stand suffering 

 windfall is located in a slight depression of the valley floor bordering 

 the Little North Fork River. This area was found to be poorly 

 drained, and as a consequence root fungi were well established in the 

 trees. An examination of the area disclosed a majority of the wind- 

 fall trees with rotted and broken roots. The area used as a contrast 

 fall area and is a portion of the same stand. The site is similar — along 

 the bottom land bordering the Little North Fork River — but is favored 

 with a slight slope toward the river, thus insuring better drainage. 

 The trees on this site were of a slightly younger age class, and upon 

 examination, following the cutting operations, it was found that butt 

 rot existed in a lesser degree and very little root rot was present. 

 These trees all withstood the storm which overthrew the stand ui)on 

 the other less favorable area. A conclusion is reached that the better 

 drained site, having very little root and butt rot, composed of a slightly 

 younger and therefore presumably sounder age class, and occupying 

 a similar position on the valley floor in respect to the path of the wind, 

 was, by reason of its sounder condition, better able to withstand the 

 overthrow force of the wind. The exposure, tree heights, crown size, 

 etc., were practically the same for the two areas, so that no other sec- 

 ondary cause of windfall than fungi could be attributed. The data 

 previously presented from the I'ricst River region also favor this con- 

 clusion. 



