234 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 3 



(California), Rosellinia radiciperda (New Zealand), Ozonium, etc., 

 have been assigned as the cause. Some of the observed fungi un- 

 doubtedly follow previous injury by low temperature, wet soil, or other 

 causes interfering with root respiration. Even the undoubted para- 

 sites may be assisted in their attack by such conditions. Selby found 

 5t more frequent on clay soil in Ohio. It is a common trouble in 

 Oklahoma and Texas. 



Gummosis 



The ordinary cells of the peach are easily transformed into the gum 

 commonly found about injured peach tissues. Gummosis usually 

 begins in some wound where gum forming enzymes develop and may 

 bring about extensive degeneration. Bacteria (see work in U. S. 

 Dept. Agriculture and Brzezinski in Compt. Rend. 1902) as well as 

 several fungi have been found associated with gummosis and in some 

 cases definitely causing it. It is usually to be looked upon as the 

 indication of some other trouble and may be associated with brown 

 rot, borers, bark beetle, scale, excess of nitrogen, and especially frost, 

 which often leaves patches of bark separated from the wood where the 

 gummosis enzyme starts to work. 



Cankers, Knots and Constrictions 



Cankers may be formed by various peach fungi keeping open 

 w^ounds' which the tree is trying to heal. Constrictions indicated by 

 the yellow, rolled foliage from uncut bud-wrappings, label wire, etc.. 

 are often seen. I have seen a few cases like the above where the 

 constriction was due to the killing of the bark which was dried to the 

 wood and covered with small pycnidia filled with Pestalozzia like 

 spores. Other causes are : overgrowing the stock as when grafted on 

 sand cherry and American plum, attacks of Fhoma persicm, other 

 fungi, etc. 



A knot of swelling of twigs is described by Selby in Ohio (1898), 

 clubbed branches noted by Erwin Smith (1892), a tuberculosis at- 

 tributed to a species of Clostridium occurs in Europe, MacOwen 

 reports at the Cape of Good Hope (1899) knotlike growth followed 

 by death of the twigs bearing them, and a case of swollen and blis- 

 tered peach trees in England is reported in Gardeners Chronicle 

 1897. 



Shot Hole and Leaf Spot 



The cause of the Shot hole effect in leaves may be difficult to find 

 as the affected portion is cut away by the peach itself. Spray injuries 



