616 THE MONTHLY BULLETIN. 



In trimming out this bark he uses a farrier's knife such as is used in 

 trimming horses' hoofs. Where the killed areas of bark are so large 

 that all the diseased bark can not well be taken off, two slits are made 

 up the trunk, one on each side of the infection, for the purpose of con- 

 fining it to one section of the trunk. Another cut is made to allow the 

 gum to drain out. The entire surface is then covered with the Bordeaux 

 paste. Just how much bark it is necessary to take out and whether 

 slitting is necessary are questions that need to be further investigated. 

 It seems advisable with our present knowledge to cut the branches back 

 more or less severely on the side where the bark has been killed over a 

 very large area. If the area is small, no cutting back need be done. If 

 the bark is allowed to become entirely dead the greater part of the 

 way around, it is then usually a waste of time to try to save it. One 

 must expect the gum to run out freely for several weeks after treat- 

 ment, even while healing is going on. One should watch for the forma- 

 tion of new healthy tissue rather than the amount of gum that is exuded 

 after treatment. The gum that has already formed under the bark 

 beyond where any fungus is found will drain out. The gum itself, as 

 has been shown by inoculation, usually does not contain any infectious 

 principle. The infectious principle (the fungus) is in the diseased 

 bark or wood at the junction of the live and dead tissue. The formula 

 that is being recommended as a result of a number of experiments by 

 growers is as follows : 



Bordeaux Paste. 



1 pound of bluestone (copper sulphate) dissolved in 1 gallon 

 of water in a wooden or earthen vessel. This can best be done 

 by hanging it in a sack in the top of the water. 



2 pounds of unslaked lime, slaked in about one half gallon 

 of water. Some variation from these proportions may be made 

 without greatly changing the value of the paste. 



Stir together when cool, making a light blue mixture about the con- 

 sistency of whitewash. If the mixture turns to some other color before 

 being applied, it is an indication that something is wrong. Mix up fresh 

 each day or two, as the mixed paste tends to deteriorate with age. It 

 may be applied with a large brush as whitewash. (Figure 351). A 

 wash made of equal parts of lime and sulphur (self boiled) is also 

 being tried out. This may prove equally as good. Many other fungi- 

 cides are being tried. 



Summary. 



Lemon gummosis in at least two forms has been found to be readily 

 transmissible from diseased to healthy trees by inoculation. 



By series of many inoculations into healthy trees it has been found 

 that the grey fungus (Botrytis vulgaris) is capable of inducing one 

 form of gummosis, and that the brown rot fungus (Pythiacystis citroph- 

 thora) is capable of inducing the other. 



Both these fungi have been isolated from trees affected with gum- 

 mosis, and after inducing gummosis in healthy trees have been reiso- 

 lated from these inoculated trees. These fungi were found to be at the 



