TIMELY HINT 118 



There are other galls and gall-like growths on plants that may 

 be mistaken occasionally by the nontechnical observer for crown 

 gall. A careful study with a good lens or microscope, however, will 

 reveal differences. Among these are galls on roots of apple and 

 pear trees caused by the woolly aphis. These are small, quite 

 irregular, and usually abundant on the roots of trees infested 

 with this pest. The small insect can often be seen on them. The 

 nematode gall is another peculiar outgrowth occurring on roots. 

 These are irregular in size and shape. They are mostly quite 

 herbaceous in texture, and when youg are whitish in color. These 

 are caused by small worms called nematodes which may sometimes 

 be seen within the gall. They are often abundant on the roots 



Fig. 1. Ciown gall, hairy root type, on root of apple trees from shipment into State of Arizona. 

 A. W. Morrill, Fifth Annual Report, Arizonn Commission of Agr. and Hort. 



of tomato plants and are also found on many other plants. Nitrogen 

 nodules should also be mentioned here as a form of root gall, though 

 a beneficial one. They are well known to most growers and occur 

 on the roots of plants of the legume or pea family. They are also 

 found on a few other plants, including members of the Elaeagnaceae, 

 of which the buffalo berry and Russian oleaster are members. The 

 horticultural inspector, at least, should be able to recognize imme- 

 diately these different galls. 



Professor Tourney, who worked on crown gall at this station 

 some years ago, stated that when the gall first begins its development 

 there is a pushing outward of a small area of the true cambium, or 

 living tissue of the plant, which is later transformed into large mis- 



