2014 



ENCYCLOPEDIA OP PRACTICAL HORTICULTURE 



Toadstool Disease. See Root Rot, this 

 section. 



Trunk Rot 



ScMzophyllum commune 



The trunk or main branches rot, with 

 a production of small, white bracket toad- 

 stools on the surface of the affected wood. 

 This fungus does not affect sound trunks, 

 but follows deep wounds, bruises, heavy 

 cutting, sunburn or other injuries. The 

 wood of the English walnut is particularly 

 susceptible to this form of decay. 



All severe cuts or wounds should be 

 carefully covered with grafting wax to 

 allow healing ever without decay. In 

 top-grafting walnut trees this should be 

 given special attention or serious decay 

 may follow. 



Wilt. See Seedling Root Rot, this sec- 

 tion. 



Yellows 



Spindling, yellow shoots develop which 

 usually die back from the tip. All degrees 

 of the trouble may occur from slightly 

 unnatural yellowing and slenderness of 

 the normal shoots to the production of 

 masses of small, yellow shoots, with con- 

 tinual dying back. This disease appears 

 to be the same which affects the peach 

 (which see), and also to some extent the 

 pecan, apple, and many other trees. It 

 is probably due to a climatic or soil con- 

 dition rather than to any parasite. Con- 

 ditions which result in sour sap and sim- 

 ilar troubles in the stone fruits seem to 

 be related to this disease, and it is very 

 likely due to a disturbance of the dormant 

 or resting condition through which these 

 trees normally pass during the winter. 

 Also seems to be connected with lack of 

 rain or irrigation late in the season. 



R. E. Smith, 

 California Experiment Station Bulletin 218. 



WALNUT PESTS 



Blister Mite. See Erinose, this section. 

 California Tussock Moth. See Apple 

 Pests. 



Erinose 



Blister-like swellings appear on the 

 leaves, sometimes becoming very abun- 



dant. This trouble is caused by an insect 

 so minute that it is not visible to the eye. 

 Not serious or requiring treatment. 



Frosted Scale. See Apricot Pests. 

 Greedy Scale. See Apple Pests. 

 Pear Thrips. See Pear Pests. 

 Red Scale. See Grape Pests. 

 Red Spider. See Apple Pests. 

 San Jose Scale. See Apple Pests. 

 Walnut Aphis, European. See Walnut 

 Callipterus, this section, also Aphids. 



Walnut Callipterus 



Ghromaphis juglandicola Kalt. 

 H. P. Wilson 



This is a little green plant louse about 

 one-eighteenth inch long which feeds on 

 the leaves of walnuts throughout the sum- 

 mer. The life history has never been 

 worked out, but we believe that it is about 

 the same as other species of this group. 

 The winter is spent in the egg stage on 

 the twigs about the buds. As the buds 

 are turning green in the spring little 

 greenish-yellow lice issue from the eggs 

 and, crawling to the opening buds, feed 

 on the expanding leaves. Towards late 

 spring winged individuals appear and mi- 

 grate to other trees, where they produce 

 living young. During the summer and 

 until late fall viviparous females are pro- 



Fig. 1. Mouse Injury to Nut Tree. 



— H. A. Qossard 



