N't*. «. DEPARTMENT OF AGRICULTURE. 221 



tory. vyhile there is a diilerence in trees and in soil this is largely 

 theoretical; 'it is never safe to fill in about a tree more than a 

 foot and the danger rapidly increases with the depth of the filling. 

 The injury may not be marked for several years. That it is not 

 more frequently caused is chiedy due to the fact that, owing to the 

 spread of roots and the inclination of the surface, some parts are 

 left unchanged or so slightly changed that root action is not ma- 

 terially alfected. There is much barbarous treatment of trees be- 

 sides cutting off their roots and surfacing about them with asphalt 

 and pavement blocks, where everything must be sacrificed to the 

 rigid level of the engineer. In case material changes in grade and 

 level are necessary, it will be, in the long run, more satisfactory to 

 remove old trees entirely and reset them, or, if they are too large, 

 to destroy them and start anew with young trees. 



3. Many of the inquiries are, naturally, respecting fungi and 

 fungus diseases of cultivated plants. They range over the whole 

 field of that voluminous subject. Some of them are simple and 

 easy, so far as determination of the fungus and the disease are 

 concerned, such as wheat rust, for instance; one soon learns to dis- 

 tinguish this at sight. A patch of rusted wheat, particularly in 

 the fall, is apt to suggest the "work of the Hessian fly, and, indeed, 

 they are frequently associated, but not probably as to cause and 

 effect; they are, presumably, independent. Kemedy for such dis- 

 eases is quite a different and a much more difficult matter, chiefly 

 because of the practical ditficulties connected with their applica- 

 tion. The expense incurred in the direct application of fungicides 

 is frequently prohibitive. Preventive measures are to be sought 

 for, and these take a wide range and often call for a nicety of knowl- 

 edge and a closeness of observation not appreciated by farmers who 

 are generally slow to change old practices. The conditions sur- 

 rounding growing plants should be the best which can be made for 

 producing a rapid, continuous and vigorous growth. Such healthy, 

 active plants have a measure of resistance to fungus attack which 

 is not possessed by weaklings. 



One must sometimes choose between a variety of vigorous growth 

 and productiveness, though of somewhat inferior quality, and one 

 which is of weaker growth and less productive, though of superior 

 quality, the former being not subject to fungus injury while the 

 latter suffers seriousl}'. Coupled with this must be proper atten- 

 tion to crop rotation, since fungus germs tend to accumulate in a 

 soil or its plant refuse under continuous cultivation of one crop, 

 and can be removed only by periodically introducing some new 

 kind of crop. Burning or removing refuse is a great aid in securing 

 immunity from injurious fungi. The particular case which called 

 out these recommendations was one in which the celery blight wa* 



