Florida Agricultural Experiment Station


as this is bound to occur as a result of the liberation of the gum
already formed under the bark.
 In treating trees attacked by either gummosis or psorosis,
 first cut off all dead branches and all those badly weakened by
 the disease. Next cut off all gum masses that may be present
 and remove all loose, scaling bark. Then carefully scrape off the
 dark, outer bark over all the affected parts of the trunk or limb
 to be treated. The scraping should be just deep enough to remove
 almost all the green layer that is found just beneath the outer-
 most dark-colored, corky layer and should not extend deeper
 than about a third of the way through the bark; otherwise the
 bark is likely to die. It is also extremely important to scrape
 the bark for a distance of from at least 4 to 6 inches above and
 below and from 3 to 4 inches laterally beyond the margin of the
 affected bark in case the lesion does not extend more or less com-
 pletely around the trunk or branch. The scraping of the bark
 in advance of the lesion can be done more lightly.
 Discolored areas that appear in the bark about the gumming
 cracks when the bark is scraped, in the case of gummosis, should
 be disregarded unless the bark is dead clear down to the wood
 or has been loosened by gum formation beneath it, in which case
 the dead area of bark may be cut out. The latter treatment in
 the case of gum pockets, however, is by no means necessary since
 the loosened bark will eventually be sloughed off after the scrap-
 ing treatment by the callus formation developed from the margin
 of the living bark. In cutting out gum pockets the excisions
 should be narrowed or slightly pointed at the upper and lower
 ends in order to secure the most rapid healing.
 After the bark has been thoroughly scraped as directed, the
 scraped area should be painted with some good, safe disinfect-
 ant paste or wash, as discussed later. All areas of exposed wood
 should then be painted with some good waterproof wound dress-
 ing to prevent the entrance of wood-boring insects and decay-
 producing fungi. The application of a fungicidal paste or wash
 to the freshly scraped bark is of value in checking the develop-
 ment of the organism causing the disease, in preventing subse-
 quent infection, and in stimulating the drying up and sloughing
 off of the outer layer of scraped bark. Of the various disin-
 fectants thus far tested, the lime-sulphur or lime and sulphur
compounds appear to be the most effective in stimulating the
bark sloughing process, while thick carbolineums, paints and