240 NEBRASKA STATE HORTICULTURAL SOCIETY. 



atid partially disintegrated before these sporophores appear, and although 

 the life of the tree is generally doomed it may often be prolonged by 

 proper care. When orchardists recognize the fact that wounds should 

 be protected to prevent infection, there will be less trouble from wood- 

 destroying fungi. 



The broom-like tufts of branches which appear on the silver fir, 

 cedar, birches, cherry and other trees are popularly called witches' 

 brooms. In the majority of cases a rust fungus is the cause of the 

 abnormal proliferation, and the resulting branches generally stand more 

 or less erect, giving the characteristic broom-like effect. Insects may 

 in some cases be the cause of witches' brooms, but there are numerous 

 instances in which the casual organism has not yet been observed. The 

 witches' broom of our common hackberry is due either to an insect alone 

 or to an insect and a fungus working together. CoQkscomb-like growths 

 are closely related to witches' brooms in their manner of formation. In 

 growths of this sort on the gooseberry a louse and a mildew are quite 

 constantly present. 



While the formation of rosettes is the normal form of growth in 

 many plants, such as the dandelion, shepherd's purse, lettuce, and others, 

 the appearance of rosettes or the assumption of the rosette habit is a 

 sure indication of disease in several cases. Very good examples of this 

 symptom are to be observed in the "rosette disease" of the potato and 

 In the "peach rosette." Both of these diseases are at present confined 

 to the eastern ahd southern part of the United States. 



There are many diseases in which the outflow of a slimy, gummy, or 

 resinous substance is a characteristic symptom. In the so-called "slime- 

 flux" of deciduous trees the exudation is semi-fluid in nature and does 

 not set into a solid substance with the accumulation of the excretion. 

 This symptom may indicate a parasitic organism or it may be due to 

 deep-seated physiological disturbances induced by other factors. In con- 

 iferous trees in which an excretion of resin is a normal phenomenon, 

 we often find an abnormal increase as a result of disease. One of the 

 first symptoms attending the presence of wood-destroying fungi in our 

 forest evergreens is this abnormal production of pitch or resin. This 

 symptom is frequently noticeable before the sporophores of the fungus 

 make their appearance on the surface of the trunk. The production of 

 a clear or amber-colored secretion which accumulates upon the surface 

 of trunk, branches or even small twigs is characteristic of the "gum- 

 mosis" of cherries, and other stone fruits. This material generally sets 

 into more or less solid, nodular or flattened masses, and the fruit 

 itself often shows numerous "gummiperlen." In peaches and plums the 

 fruit from affected trees often shows a splitting apart of the halves 

 of the pit or stone. In general, however, cherry trees and peach trees 

 suffer more from gummosis than any other stone fruits. In some cases 

 gummosis is induced by wounds, in others it is a symptom attending 

 the presence of a fungus parasite, while in many instances it Is due 



