asphaltum paint containing 0.2 per- 

 cent phenol-mercury nitrate, a power- 

 ful fungicide. 



One might want to treat the wound 

 caused by pruning dead and undesir- 

 able branches from a tree. Many hard- 

 ware stores and paint stores sell tree 

 paint or tree wound dressing, which 

 usually is obtainable in either plastic 

 or liquid form and practically always 

 has an asphalt-base paint. 



Ordinary asphalt roofing paint is 

 satisfactory, but it is not antiseptic. 



Some fungi develop in the wood of 

 living trees and cause wilt and dieback 

 of the tops. They are difficult to con- 

 trol; for the most part, no adequate 

 means of combating them have been 

 developed. Verticillium wilt of elm and 

 of maple, however, can sometimes be 

 overcome by fertilizing the affected 

 trees, improving the condition of the 

 soil in which they are rooted, and 

 watering heavily during dry spells. 



Some kinds of fungi require more 

 than one kind of plant to complete 

 their life cycle. For example, one kind 

 of gall that develops on the common 

 redcedar is caused by a rust fungus. To 

 develop, the fungus spores produced 

 on the galls must be transmitted to an 

 apple or closely related tree, on which 

 they cause leaf and fruit spot. The 



Yearbook of Agriculture 1949 



spores are then carried back, by the 

 winds or otherwise, to redcedars, 

 which they infect. The rust fungi that 

 have such a life history generally can 

 be controlled by spraying, but some- 

 times one can avoid such diseases by 

 eliminating one of the host plants. 



Along the northeastern seaboard, ash 

 rust sometimes becomes epidemic; the 

 fungus that causes it develops on 

 marshgrass, which sometimes is used 

 as a mulch in orchards. 



DECAY OF THE WOOD of limbs and 

 trunk can be combated by removing 

 the affected parts or removal of the 

 decayed wood. Sometimes the cavities 

 made in removing decayed wood are 

 filled with concrete or other materials ; 

 sometimes they are left open. 



Wood decay fungi often gain en- 

 trance through wounds that expose 

 sapwood or heartwood. Avoidance, in- 

 sofar as possible, of wounding and 

 painting of accidental wounds and 

 pruning cuts over 1/2 inches in di- 

 ameter will assist in the prevention of 

 wood decay. 



CURTIS MAY is a principal pathol- 

 ogist in the Division of Forest Path- 

 ology, Bureau of Plant Industry, Soils, 

 and Agricultural Engineering, United 

 States Department of Agriculture. 



THE PHOTOGRAPHS in the next section were chosen to summarize the main 

 points in this book and to awaken interest in the purposes and pleasures of trees 

 and forests: 



Our forests are diverse in types, ex- 

 tent, and uses. 



They are a living part of every Amer- 

 can's life, whether he lives in Puerto 

 Rico, North Dakota, Alaska, whether 

 in Maine or Hawaii. 



They provide paper, recreation, 

 furniture, foods, feeds, protection from 

 wind and flood, homes for birds and 

 other wildlife, and so many other 

 products and comforts that no man has 

 counted them all. 



Forests protect hillsides and moun- 



tainsides and make on them living res- 

 ervoirs of water. 



Trees and forests, however, are not 

 something only on a far mountain. The 

 trees at our own doors are neighbors, 

 friends, and helpers. 



These trees, these forests, need care. 



We are making great strides in car- 

 ing for our trees and forests. We have 

 new machines, uses, cutting methods, 

 knowledge of breeding trees, improve- 

 ments in watershed practices, fire fight- 

 ing, planting, marketing, and more. 



