47 



(iuiis ((M»k |il;i(<' l;is( siiiiiiiirr in llic lliidson Ki\ci- \';illcv \\;iS 

 ('\i<lcii( I V iilioiil (lie liiiic w Im'Ii I li(i asc().s|M)re slagi* was just 1»C'- 

 (•(»iiiiii<; al)uii(hiiil. 1 1 is :iii iiiiporfant matter tlioii to (k'tonniiic 

 (lie spore sla.nc mihI I lie au<'ii( y rcspoiisildo for the spread of the 

 I'liiiuiis Im'Ioit wc can hope lo a(l\ise an cniciciit and effective con- 

 (i-ol. I'(»r ('xain|d(', sndi incfanlionai'V mcasnrcs as (he peelinj; 

 (•r h>,iis before alh)\\iii<; them (o he moved eonhl hi.' limited to the 

 time of year when thi« was necessary ami thus ohviate a j^reat 

 cost. 



Likewise (he pi'ohlem as to li()\v (lie i>resent ei)i(lemieal char- 

 act(;rs exhibited by the disease have come about is as far from 

 solution as it Avas six years n^o. The speaker has recently col- 

 lected and examined a fungus indis(ini;uishable from the chest- 

 nut canker disease fungns on dead chestnut bark in several 

 places in Virginia. No case of this fungus attacking living 

 trees "was found in the short preliminary examination made near 

 L^nchbnrg, although several specimens were collected on dead 

 bark of stumps from which trees were cut a1)out two years ago. 

 Also a fungus found in I'ennsylvania on wliite, red and black 

 oak has great similarily to the canker disease fungus. The pos- 

 sibility of having several strains of the same fungus identical as 

 to microscopic characters, some saprophytic and others causing 

 a virulent disease, is at once puzzling. One of two things has 

 evidently happened, either the host plant has, under existing 

 conditions, been altered in its physiological process enough to 

 change its susceptibility to this heretofore saprophytic fungus, 

 or the fungus has developed a parasitic habit independent of 

 any change in the host. Possibly, of course, both factors may 

 have combined to bring about this disease-condition. Prelim- 

 inary investigations carried on by the speaker seem to point to 

 the fact that the susceptibility of the chestnut tree to this fungus 

 depends upon drought conditions; that is a low water content in 

 (he tree. This requires confirmarion hoAvever by further detailed 

 ex])eriment. Weather conditions causing winter injury as sug- 

 gested by Dr. Clinton may quite possibly be of importance also 

 in this connection, and accurate data concerning past weather 

 conditions and experiments to determine the effect of low temper- 

 ature on the chestnut tree in connection with the production of 

 susceptibility is highly important. 



