THE MONTHLY BULLETIN. 277 



The eastern white pine forests are separated from the western five-needle pities by 

 the natural barrier of the Great Plains. There is little danger of the fungus jumping 

 this barrier except through shipments of stock, or more slowly through a chain of 

 cultivated or wild currants and gooseberries. It follows that protection of the 

 hitherto untouched western part of the country can only be effected by a careful 

 watch of its frontiers and rigid exclusion of all stock coming from the outside. 



CHESTNUT BARK DISEASE. 



One nf the most popular trees of the Eastern States is the American chestnut. 

 As a forest tree it yields large quantities of excellent lumber. As a much prized and 

 highly ornamental shade tree it graces parks and gardens, and in orchards it produces 

 sweet nuts in abundance which form a nourishing food. Estimates of the total value 

 of chestnut vary from 300 to 400 million dollars. The total value of chestnut 

 products (lumber, poles, ties, etc., and tanning extracts), not counting the nuts, in 

 the year 1011 reached almost $20,000,000. Virginia alone in the same year exported 

 $200,000 worth of nuts. Of the enemies of the American chestnut at that time little 

 \\:is known. The tree seemed to be fairly immune from serious diseases. 



In the year 1004 a disease, killing twigs and branches, was observed in the New 

 fork Zoological Park without at the time attracting much attention. In the follow- 

 in- year it had made such progess that serious alarm began to be felt. In 1011 it 

 had spread over at least ten eastern states and the damage was very conservatively 

 estimated at .$25,000,000. Huge as this figure seems, it is trifling compared to the 

 total value of the chestnut stand which now is in imminent danger of complete 

 destruction. 



The virulence of the attack and the rate of spread of the disease are without 

 parallel in the history of plant diseases. The disease is absolutely fatal. Local 

 attacks may. at great expense, be suppressed. Where the disease has once gained a 

 firm foothold, its eradication is as good as impossible. The United States Depart- 

 ment ..f Agriculture and the state of Pennsylvania have from an early date on 

 undertaken extensive .studies of the disease and have been active in its control, partly 

 in the suppression of local outbreaks, partly in preventing the spreading and estab- 

 lishment of new centers. 



The disease was first believed to be of American origin. Not until 1013, however, 

 was it found that the disease was indigenous to China and widely spread in Japan. 

 In both countries the actual damage to native chestnuts, though noticeable, does not 

 reach alarming proportions. There remains no doubt that the disease was actually 

 introduced from Japan into the I'nited States, where it found a particularly sus- 

 ceptible host in the American chestnut (Castanca dentata). 



The disease shows plainly from a distance. The first symptom of attack manifests 

 itself in discoloration, wilting and drooping of the foliage (Fig. 82), which persists 

 en the tree during the winter. After the winter storms have removed the leaves of 

 the stem or branch attacked, the latter stand out naked from the green foliage of the 

 still healthy part of the tree. An attack during the early part of summer will 

 prevent the burs from developing to their full size. A late attack finds the burs 

 fully developed. In this case the burs remain on the tree during winter, instead of 

 dropping off in fall (Fig. 83). Another symptom of the chestnut bark disease 

 consists" in the formation of suckers at the base of killed stems. It is the same 

 tendency of regeneration found so commonly in broad-leaf trees after felling or 

 girdling. In fact, the effect of the disease is the same as that of girdling. 



