446 



Illinois Natural History Survey Bulletin 



Vol. 23, Art. 4 



rium. Wilt was not produced by these in- 

 oculations, nor by inoculations of buds, 

 leaves, shoots or branches. Infection was 

 not obtained by patch grafting with dis- 

 colored inner bark taken from diseased 

 trees. 



5. Sap from wetwood caused young 

 trees to wilt when it was introduced into 

 their current-season wood. It appears that 

 grajash brown streaks in the current-sea- 

 son wood are caused by the discolored sap 

 and not by the wetwood organism. The 

 bacterium was not often isolated from 

 wilting branches. 



6. Trunk pressures in wetwood-affect- 

 ed elms commonly reached 5 to 30 pounds 

 per square inch, and were highest in trees 

 that did not flux. A pressure of 60 pounds 

 per square inch was recorded in one tree 

 in 1942. Pressures in wetwood-affected 

 elms began to develop in April and early 

 May, increased until August or Septem- 

 ber and then decreased until late Decem- 

 ber or January. Pressures were not detect- 

 ed in February and March. In artificially 

 infecteid greenhouse trees, pressures fol- 



lowed a diurnal cycle with a maximum 

 between 11:00 a.m. and 1:00 p.m. and 

 a minimum between 7 : 00 and 1 1 : 00 p.m. 



7. Gas from affected elms contained 

 methane, carbon dioxide, oxygen, hydro- 

 gen and nitrogen. 



8. Sap from affected elms contained 

 phosphates and potassium. 



9. The pH determinations showed the 

 sap and discolored wood of wetwood trees 

 to be alkaline, the wood of healthy trees 

 to be acid. 



10. The bacterium which causes wet- 

 wood is a fermenting facultative anaerobe 

 of the genus Erwinia. It is named Erwinia 

 nimipressuralis, new species. 



11. Control measures tested included 

 feeding with 10-8-6 fertilizer and urea, in- 

 stallation of drains in trunks, and the in- 

 jection of mercuric chloride, copper sul- 

 fate, silver nitrate, 8-hydroxyquinolin sul- 

 fate and Helione. Neither the use of fer- 

 tilizers nor the injection of any of the 

 chemicals appeared to be effective. The 

 installation of drains, however, gave at 

 least temporary control of flux. 



LITERATURE CITED 



Beilmann, August P. 



1935. The use of instruments in tree diagnosis. Natl. Shade Tree Conf. Proc. 11: 18-26. 



1940. An attempt to record internal tree-trunk pressures. Mo. Bot. Gard. Ann. 

 27(3) : 365-70. 



Burkholder, Walter H. 



1932. Carbohydrate fermentation by certain closely related species in the genus 

 Phytomonas. Phytopath. 22(8) : 699-707. 

 Conner, H. A., W. H. Peterson and A. J. Riker 



1937. The nitrogen metabolism of the crown gall and hairy root bacteria. Jour. Ag. 

 Res. 54(8) : 621-8. 

 Connors, Charles H., and Victor A. Tiedjens 



1941. Chemical gardening for the amateur. Wh. H. Wise and Company, New York. 

 225 pp. 



Cook, Mel. T. 



1918. Common diseases of shade and ornamental trees. N. J. Ag. Exp. Sta. Circ. 98. 

 27 pp. 



Crandall, Bowen S. 



1943. Bacterial infection and decay of the inner wood of winter-injured young London 

 plane trees. Phytopath. 33(10) : 963-4. 

 Crandall, Bowen S., Carl Hartley and R. W. Davidson 



1937. Wetwood. (Abstract.) Phytopath. 27(2) : 126. 

 Crocker, William 



1931. The effect of illuminating gas on trees. Natl. Shade Tree Conf. Proc. 7: 24-34. 

 Crocker, William, P. W. Zimmerman and A. E. Hitchcock 



1932. Ethylene-induced epinasty of leaves and the relation of gravity to it. Boycd 

 Thompson Inst. Contrib. 4(2) : 177-218. 



Dodge, A. W. 



1937. Slime flux. Arborist's News 2(7) : 1-2. 



