Sap-Flow Flux, Flurus umbilicalis, a disease frequently occurring in plants and trees, when the alburnum, or sap-wood, is wounded during the spring; and which consis s of a saccharine, mucilaginous fluid, resembling honey-dew. This affection occasions great trouble, especially when vines in hot-houses are pruned too late in the season ; for the whole branch is liable to bleed to death, in con-sequnce of the loss of the sap, which ought to supply the young buds with nutriment, and expand their foliage.
There are some perennial plants, such as the cow-parsley, or Hera-cleam sphondylium, L. the roots of which, if the stems be severely wounded, or entirely cut off, when they have attained a certain height, are liable to decay in consequence of this flux, or loss of the umbilical fluid. - Hence Dr. Darwin observes, it has been recommended to mow down, early in the spring, thistles, and such other noxious weeds as are troublesome, on account of their rapid increase; because many of them will perish, and the rest will be considerably weakened by the great discharge of sap that flows from their wounds at that season.
With respect to trees, there is another period of sap-flow, that occurs when the new buds are forming, after Midsummer. It is therefore very injurious to wound trees at that period ; and, as their vegetation is thus endangered, different applications have been recommended- by gardeners. Dr. Darwin is of opinion, that a bit of sponge, if bound upon the end of the cut branch, or upon the wound, by means of some elastic bandage, will be the most certain remedy to save them ; or, a wire may be substituted for the sponge, if twisted so tightly round the end of the maimed branch, as to check the circulation of the juices, and consequently to destroy the part above the ligature.