18 A DISEASE OF THE WHITE ASH. 



REMEDIES. 



The white ash is becoming more valuable as a lumber tree, and it is 

 being grown extensively as an ornamental tree in parks and grounds. 

 In limited areas it will pay to adopt measures which will tend to pre- 

 vent the disease described in the foregoing pages, or at least to recog- 

 nize diseased trees and use them for lumber, so as to save the parts 

 still sound. A disease such as the white rot of the ash is a difficult 

 one to combat after a tree is once badly diseased, for the fungus 

 grows in the interior of the trunk, where it can not be reached. Trees 

 which grow in forest tracts should be cut down when badly diseased, 

 so as to prevent the spread of fungus spores. That a persistent cut- 

 ting out of diseased trees will in a comparatively short period reduce 

 the number of newly infected trees has been demonstrated repeatedly 

 in European forests, where it is now often impossible to find many 

 well-known forms of disease which were formerly comparatively 

 common. 



In parks and grounds diseased trees, when they appear healthy 

 otherwise, need not necessarily be cut down, for the trees may remain 

 alive and vigorous even when the heartwood is partially decayed. 

 The only danger is that trees weakened in that way are liable to be 

 broken off by windstorms. A diseased tree can be recognized as 

 soon as the white punks or sporophores appear at a knot hole. As 

 soon as a punk appears it can be cut out, and some of the diseased wood 

 with it. The hole should then be tilled with tar oil and left open for 

 a time. Tar oil should be added from time to time, as a good deal will 

 soak into the decayed wood, and thereby arrest the further growth of 

 the fungus to some extent. If the hole made by removing the punk 

 is a large one it should be covered with tar paper, so that no opening 

 is left for water or dust to enter. 



A sure method of combating this disease is by a careful system of 

 pruning and the coating of all wounds with an antiseptic substance. 

 Vigorously growing ash trees heal wounds rapidly, and after three or 

 four years any ordinary-sized wound will be completely occluded. In 

 treating trees planted in parks or gardens the pruning had best be 

 done in the winter. Care should be taken to cut all branches as close to 

 the trunk as possible, and after trimming the ragged edges of a cut 

 the whole surface should be coated. Ordinary gas tar is the best sub- 

 stance for this purpose. If too hard it should be heated so as to be 

 fairly liquid and then applied with a brush. The gas tar, especially 

 when warm, penetrates for a considerable distance into the wood and 

 prevents the development of the ash fungus. It forms an air-tight 

 and water-tight cover which is not destroyed by weathering, and which 

 at the same time is objectionable to insects. 



Where the coating of wounds is carried on with care it will be 

 entirely practicable and possible to prex^ent this ash disease. 



