DISEASES OF THE CHESTNUT AND OTHER TREES 75 



the appearance of the bark itself, but the pustules show in the 

 cracks and the bark often sounds hollow when tapped. After 

 smooth-barked limbs or trunks are girdled the fungus continues to 

 grow extensively through the bark, sometimes covering the entire 

 surface with reddish-brown pustules. These pustules produce 

 mostly winter spores (ascospores), although occasionally the long 

 strings of summer spores (conidia) are also produced, even on bark 

 that has been dead at least a year. 



After a branch or trunk is girdled, the leaves above change 

 color and sooner or later wither. Such branches have a very char- 

 acteristic appearance and can hardly be mistaken for anything 

 else, except in certain localties where the work of twig-girdling in- 

 sects may produce a similar appearance in the spring. In case 

 girdling by the fungus is completed late in the season, the leaves 

 of the following spring assume a yellowish or pale appearance and 

 do not develop to their full size. If the girdling is completed 

 between spring and midsummer the leaves may attain their full 

 size and then turn a somewhat characteristic reddish-brown color, 

 which can easily be detected at a long distance. Later this leaf 

 coloration changes to a more brownish tinge and the leaves are com- 

 monly persistent for a considerable time. The chestnut burs on a 

 spring-girdled branch may or may not attain full size, according 

 to whether the girdling by the disease was completed late or early 

 in the spring. These burs commonly persist on the tree during the 

 following winter, thus producing the only symptom which is at all 

 conspicuous from a distance during the leafless season. The great 

 damage which the disease has done in late summer thus becomes 

 most evident at the beginning of the next season, and that done in 

 the spring becomes evident later in the season, giving rise to 

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

 time of year that the leaves change color, when in reality the 

 harm was done much earlier. 



Perhaps the most easily seen as well as the longest persistent 

 symptom of the bark disease is the prompt development of sprouts, 

 or " suckers," on the trunk of the tree and at its base, or some- 

 what less frequently on the smaller branches. Sprouts may 

 appear below every girdling lesion on a tree, and there are usually 

 many such lesions. These sprouts are usually very luxuriant and 



