. Die-Back, Guin and Root-Knot. 459 
water in the soil, and the remedy is drainage. Trees thus af- 
fected make an effort to grow and then the young growth shriv- 
els. Severe cutting back of the top to reduce evaporation until 
the roots can restore their feeding fibers is the only treatment 
of the tree, and its success depends upon the extent of the root 
injury. Sour sap may also be caused inthe branches by the 
occurrence of frost after the sap flow has actually started. Cut- 
ting back the diseased parts, as soon as discovered, to sound 
wood, is the proper treatment. 
Die-Back.—Dying back of twigs or branches may occur 
without parasitic invasion through root-weakness or partial fail- 
ure. It may be due to standing water or to lack of soil moisture, 
either of which will destroy the root-hairs and bring the tree into 
distress. The treatment is cutting back td sound wood and cor- 
recting the soil conditions, either by irrigation or drainage, as 
one or the other may be needed to advance vigorous growth in 
the tree. 
Guimmosis.—This is a convenient term to designate the gum- 
ming which is seen on many kinds of trees. As has been said 
of die-back, gumming may result from excess of water or of 
drouth in the soil, Gumming is, therefore, not considered in 
itself a disease, but rather an indication of conditions unfavora- 
ble to the thrifty growth of the tree. It has been usually found 
by investigation that trees in perfect condition of health, with 
the. moisture just enough and not excessive, are not troubled 
with gumming; but there are cases in which this statement does 
not wholly apply. There is very much in this connection which 
is not fully demonstrated as yet. Many treatments are pro- 
posed. It is a good thing to cleanly remove all the unhealthy 
bark—cutting clean to sound bark and covering the wound with 
paint or wax to exclude the air. Some report success with an 
antiseptic wash—diluted crude carbolic acid and the Bordeaux 
Mixture have both been used, and reported upon favorably. 
Root Knots—These are excrescences upon the roots or at 
the root crown of various trees and of grape-vines, and they have 
been a serious trouble in this State for a good many years. 
Althougi the knot has been studied by experts in plant pathol- 
ogy, no exact cause of the trouble has yet been found. A satis- 
factory treatment has, however, been discovered. If the knot 
has not increased in size sufficiently to seriously interfere with 
the growth of the tree it can be smoothly removed, the wound 
treated with the Bordeaux Mixture, and the knot will not reap- 
pear at the same place. Success has also been had with boring 
a hole into the knot and filling the hole with bluestone solu- 
tion. Bluestone can be used with least danger when the tree 
is dormant. 
