68 



tlirougbout the spring, tliroiigh tlie JioL <lr,y weaUior of early 

 J11I3, and the drought of July and August. lu early September, 

 two da3 s after the almost unbroken week of rain during the lat- 

 ter part of August, these chips were again examined, and on a 

 few of them whicli were composed entirely of bark, two or three 

 inches long and half as wide, many spore threads Avere found. 

 These, remember, from chips that had been lying on the ground 

 for more than five months through the hot summer drought. Pos- 

 sibly this may be regarded as an extreme case, but in any event 

 it clearly emj)hasized tlie necessity of extreme care in destroying 

 all diseased bark, chi]3S, etc., in all attempts to control the dis- 

 ease. Again, extreme cases of the sort mentioned are often the 

 very ones that must be guarded against. In certain instances a 

 gasoline torch has proved an efficient adjunct for the burning out 

 of the diseased spot and thus destroying the fungus, whether or 

 not followed b^^ the gouge and mallet. 



(5). Insects. 



Soon after beginning work on the diseasti in 1!)(I8, onr alten- 

 tion was irresistibly drawn to tlie evident intimate relation that 

 insects bore to the spread of the disease. It is singularly inter- 

 esting to note that practically ever3' person who has been work- 

 ing on the disease in the field for an}- length of time has, sooner 

 or later, been strongly impressed with this very apparent inter- 

 relationship between insects and the chestnut bark disease. Per- 

 sonalh', we have made many observations upon the topic, but ari 

 this Avork properly belongs to another Bureau of the U. S. Dept. 

 of Agriculture, we have limited our work to observations. Here 

 is a phase of the work tliat Ciuihl easily influence the plans of 

 control to a large extent if Ave knew absolutely the relation of 

 insects to the disease. It is gratifying to know that the Commis- 

 sion has an expert entomologist already at work on this particu- 

 lar part of the general pr()l)lem. 



(6). Immunity. 



From what is now known regarding the spread and virulence 

 of the Chestnut Bark Disease, there seems little immediate 

 promise of individual trees or variations of the American Sweet 

 Chestnut (Castauca ilentata) developing immunity. As this 

 species is the only forest tree of the genus in the country, it 



