346 OHIO EXPERIMENT STATION: BULLETIN 214 
ROOT DISEASES AND ROOT-ROT FUNGI OF ORCHARDS 
Diseases upon the roots of herbaceous plants are very commonly 
due to soil infesting parasites. As explained under that topic, the 
soil conditions may be favorable to certain parasitic organisms or 
without being especially suited to them soils become infested with 
fungi which tend to remain indefinitely and become a source of loss 
in crops and effort. See lettuce rosette, tobacco root-rot, potato 
dry-rot and root-rot of violet. 
The root-rots of woody growths are commonly more or less 
truly wood invading fungi of the semi-parasitic type and become of 
interest to foresters as wellas orchardists. A partial exception to this 
wood-invading character of these root-rot fungi is found in a recently 
discovered development of the tobacco and violet root-rot fungus, 
Thielavia basicola Zopf., upon catalpa seedlings in nursery. However, 
since even tree seedlings in their early stages have not developed their 
woody tissues to any great extent, they are susceptible to the same 
root parasites as are found on herbs. ‘This will likely explain cases 
like that cited on catalpa and the trouble may pass as the seedlings 
become older. Yet it must be confessed that this still raises a ques- 
tion as to the effect of the general parasitism of even Thielavia upon 
the rootlets of trees like catalpa. 
In forest woodlots, root-rots are likely to become of increasing 
effect. Wherever these tend to limit the reproduction of certain 
species in the woodlot, they will be injurious. In this respect they 
may prove an added reason for the rotation of conifers with decid- 
uous growths. In coppice or cut-over lands such as prevail in the 
charcoal furnace districts of Ohio, the roots and stumps of the 
parent stem must be an eventual menace to the'new growths which 
spring up about them. The exposure to the wood fungi which 
become timber or heart-rot sorts will be very great in all such cases. 
The gradual invasion of the new growths must often occur when 
these approach a size that gives a considerable heartwood cylinder. 
These are the great sources of trouble in coppice reproduction of 
timber trees. 
Root-rots in orchard plantings are known more especially when 
these are made following oak and other species somewhat after the 
manner of coppice conditions. The rhizomorphic development of 
these root-rots is difficult to determine but is usually referred to 
Agaricus melleus (Armillaria mellea). See root-rots of apple, 
peach, etc. 
An especial feature to be noted in root-rots of all sorts are the 
soil conditions as toexcess moisture and aeration of the soil. In 
silty or clay soils of close texture and coagulable nature, with excess 
moisture, serious conditions arise. Any traces of root-rot fungus 
