THE MONTHLY BULLETIN. 279 



then keep it several years in alfalfa before planting the orchard. How- 

 ever, in view of the scattered nature of infections and the impatience 

 of planters, it does not seem worth while to insist on such a program. 



Treatment oP individual trees may have a certain value, but usually 

 will be tlisappointing and is* doubtfully worth while for orchard trees. 

 If the crown of an affected tree is uncovered and by a generous amount 

 of digging all diseased roots are removed, or the diseased bark scraped 

 off and the wood treated as recommended in my paper on wood decays, 

 and the place allowed to dry out well, the remaining roots Avill orow 

 freely, provided the tree has not been girdled by the fungus. By 

 repeating such treatment and by keeping the crown as dry as practicable, 

 it is entirely possible that a tree may be kept alive for many years. 



Treatment of Spots. We have insisted that two problems are 

 involved: 1st, checking the outward advance of the fungus .so that new 

 trees will not become affected, and, 2ud, treatment of area already 

 infected. 



Treating the margin of the spot has been practiced, I understand, in 

 German forests by digging a ditch about the affected area so as to 

 enclose all the fungus. The fungus travels along the roots and a ditch 

 makes a space which it has no way to pass. We have some experiments 

 under way to test this method. Our orchardists object to an open ditch, 

 so we allowed the ditches to be refilled. One spot ditched was in an 

 orange orchard in good, mellow soil, trees good and more than ten 

 years old. There were two dead trees and two infected at the root 

 but with the tops still fine. The ditch was made 3 to 34 feet deep, no 

 wider than necessary for digging. It seemed to have cut all the roots'. 

 Infected roots could be readily recognized. As finished it was believed 

 that no diseased orange roots crossed outside the ditch. A layer of 

 tarred building paper of good quality was put against one side of the 

 ditch to prevent new roots from crossing back into the diseased area. 



After a little more than two years the ditch was reopened. The build- 

 ing paper was worthless for stopping the roots, as they grew through 

 it very readily. The rest of the experiment was highly encouraging. 

 In repeated cases a root from which a piece had been cut out could be 

 recognized unmistakably on the two sides of the ditch. The piece 

 within the diseased area would be in an advanced condition of decay 

 with the fungus, while the end toward the unaffected tree and outside 

 the diseased area would be entirely unattacked and putting out numer- 

 ous new roots. There could be no reason to doubt that if the ditch 

 had not been made the fungus would surely have followed the root and 

 there would have been no hope of saving the tree. Around this area, 

 which included four diseased trees, no less than five good trees were 

 saved from infection. If once opening the ditch will save the sound 

 trees from infection for two years, there is no reason why the thing 

 can not be done again in the same place and the spot permanently 

 restrained to its present area. 



Several points in the work should be noted. In one case unintention- 

 ally a diseased piece of root was thrown back into the ditch. The new 

 roots which had grown out from the healthy side had come in contact 

 with this and were already diseased, but this infection had not gone 

 far back toward the good tree. I believe we succeeded in removing all • 

 of this infection. 



