t'iisilv waslied down over the surface of the hark h_v rains, perhaps 

 to lodge in a wonuhoh' «»r oilier wound in the hark, where they can 

 develop into uiinute plants. Frnui these isolatt^l tiees as ceu*(^r:-., 

 the spores of these new plants ran readily he dislrihuted to surround- 

 ing trees hy s(piirr(ds, hirds, insects, etc. 



It is not yet definitely determined what agc-ney is most concerned 

 in distrihuting the spores, hut it appears ])rohahle that insects are 

 closely connected witli the |»i(»gi-ess of the disease. The sticky spores 

 are easily carried upon the legs and bodies of beetles and moths. So 

 far as is known at ])resent, in order to cause an infection, the spores 

 must enter a wouml or an abrasiciii in th' Itark. hence the boring in- 

 sects are esftecially harntrnl on acconni of the holes they make through 

 which the sj)ores may eiuer. These holes are moist, and some of tlie 

 spores which wash down the trunk are likely to enter these damp 

 chambers and germinate. Ants, which are fouml crawling all ovei- 

 trees, are known (o have eaten the sjioi-es from the surface of the 

 fruiting bodies, and may ihtis have Ix'come etfe<-iive agents for spread- 

 ing the disease fiom tree, to tree in an infected locality. Several 

 other species of insects which affect chestnut trees appear abnormally 

 abundant, and their relation to the spread of the disease is now 

 being studied. Birds, as a factor in spreading the disease over longer 

 distances, liav(; already been mentioned, but they are possibly also 

 effective in spreading the disease locally from tree to tree, by carry- 

 ing the sticky spores on their feet from infected branches to those 

 that are healthy. Woodpe-ckers, nuthatches, and other birds which 

 bore into the bark for insects have been observed visiting the blight 

 cankers. The wind blows numy of the spores about, either mixed 

 with dust or as fragments of broken "s])ore horns." The winter 

 spores are forced out of the pustules into tlie aii- and the wind also 

 is a factor in their distribution. When the suiiiiik r sjiores are in the 

 ''horn" stage, or when fragments of a horn are carried to other ti-ees, 

 the gelatinous mass is readily dissolved by Hie first rain, and the 

 spores washed down to lower jxisi lions on the tree where new infec- 

 ti(»ns are started. 



Infection appeal's to take ]dace only ilnongli a wound in ilie 

 bark. The fungus feeds on the iniu'r and middle bark and usually 

 quickly girdles the trunk or branch on which it grows. A cankta- 

 three inches in diameter has been observed lo develoj) in five weeks. 

 Small trees may die in a single season, and large ones are killed in 

 from two to four seasons after the blight attacks them. In the mean- 

 time, half, or jierhaps nearly all, the nearby chestnut trees may be 

 expected to show the disease al some stale of (hn-eloiiment. 



Diseased logs, cord wood, bark, etc., hauled along public highways 

 or on railroads, may carry the sjiores to new localities. Shipment 

 and planting of disea.sed chestnut nuiserv stock is another wav in 



