644 INSECTS AFFECTING VEGETATION 



form of long irregular "horns," or strings, at first greenish to bright 

 yellow in color, becoming darker with age. In this illustration the 

 typical appearance of the pustules in damp weather and the projec- 

 tion of the spores of the fungus in the form of horns, or threads, are 

 shown. These threads may be especially conspicuous near the edges of 

 diseased areas. If the spot is on the trunk or a large limb with very 

 thick bark there is no obvious change in the appearance of the bark 

 itself, but the pustules of the fungus show in the cracks of the bark 

 and, on account of the destruction of the layers beneath, the bark 

 often sounds hollow when tapped. A patch usually grows fast 

 enough to girdle the branch or trunk that it is on during the first 

 summer. 



The damage may not be immediately apparent, since the water 

 supply from the roots continues to pass up through the compara- 

 tively uninjured wood to the leaves, but when in the following spring 

 the new leaves are put out they are usually stunted and soon wither. 

 The imperfectly developed leaves often persist on the dead branches 

 throughout the summer. 



The great damage which the disease has done thus becomes most 

 apparent in the last week of May or the first week in June, giving 

 rise to the false but common idea that the fungus does its work at 

 this time of the year, when in reality the harm is done during the 

 previous summer. If the first attack is on the trunk, of course the 

 entire tree dies. If, on the other hand, the small branches are first 

 involved, the tree may live for several years. 



States have suffered from a disease during the past twenty years, 

 since, as already stated, that is a totally different thing from the bark 

 disease. 



Where the bark disease is already firmly established and has at- 

 tacked 50 per cent or more of the chestnut trees, as in the vicinity of 

 the city of New York, it is probably too late to try to do anything, 

 but where the disease is just appearing there is no reason to doubt 

 that strict quarantine methods will apply as well to this as to any 

 other disease, whether of plants or animals. The question to settle is 

 simply which is more costly to use the methods recommended or to 

 lose the tree. The people concerned must decide. (F. B. 141.) 



The Extent of the Bark Disease. The bark disease of the chest- 

 nut has spread rapidly from Long Island, where it was first observed, 

 and is now reported from Connecticut, Massachusetts, Vermont, New 

 York as far north as Poughkeepsie, New Jersey, Pennsylvania, and 

 possibly Delaware. It is no exaggeration to say that it is at present 

 the most threatening forest-tree disease in America. Unless some- 

 thing now unforeseen occurs to check its spread, the complete de- 

 struction of the chestnut orchards and forests of the country, or at 

 least of the Atlantic States, is only a question of a few years' time. 



Observations made by the writer during the past year indicate 

 that all varieties and species of the genus Castanea are subject to the 

 disease except the Japanese varieties (Castanea crenata).^ All of the 

 latter that have been observed in the field or tested by inoculations 

 have been found immune. This fact can hardly fail to be of fundtv- 



