August, 1945 



Carter: Wetwood of Elms 



437 



per cent) is very small — less than the 

 probable error in a combustion analysis. 

 MacDougal (1932) reported that marsh 

 gas, composed mostly of methane, or any 

 other inflammable gas had not been found 

 in normal trees. 



No tests were made in the present in- 

 vestigation to determine whether the gas 

 from the wetwood-affected trees was toxic 

 to foliage of elms. Crocker ( 1931 ), Crock- 

 er, Zimmerman & Hitchcock (1932) and 

 Krone (1937) pointed out that natural 

 gas, which contains about 80 per cent 

 methane, is not highly toxic to trees and 

 other plants. 



Gas was produced in abundance when 

 the wetwood organism was grown in 

 nutrient broth plus dextrose. The carbon 

 dioxide content of six samples of this gas 

 was determined by absorption with N/5 

 sodium hydroxide and the hydrogen 

 content by passage of the gas through a 

 palladium tube. The samples contained 

 approximately 44.7 per cent carbon 

 dioxide and 2.4 per cent hydrogen. How- 

 ever, it was found that the amount of 

 carbon dioxide contained in the gas varied 

 with the age of the culture and with the 

 rate of fermentation. More carbon dioxide 

 was produced in young cultures, when 

 the rate of fermentation was most rapid, 

 than in old cultures. 



Sap Analysis 



Sap from the trunk wood of elms affect- 

 ed with wetwood was analyzed for cal- 

 cium, chlorides, copper, iron, magnesium, 

 manganese, phosphate, potassium, sulfates, 

 zinc, nitrates, nitrites, ammonia, starch, 

 reducing sugars, indole and erythrodex- 

 trin. Also, different quantities of distilled 

 water in which healthy tissue and wet- 

 wood tissue had been soaked were analyzed 

 for the materials listed above. The meth- 

 ods used in analyzing for these different 

 materials were those given in publications 

 of the Society of American Bacteriologists, 

 Committee on Bacteriological Technic 

 (1939), Merck and Compan\', Inc. 

 (1940) and Connors & Tiedjens '(1941). 

 Many of these methods were supplement- 

 ed by recommendations of Dr. O. W. 

 Rees, Chemist, Illinois State Geological 

 Survey. 



Sap that accumulates in large amounts 

 in elms affected with wetwood can be 



collected by tapping the trunks of affected 

 trees. In all healthy elms tapped during 

 this experiment, sap was not present in 

 the wood in sufficient quantities to be 

 collected. Analyses were made of distilled 

 water in which wood samples from healthy 

 trees and from wetwood-affected trees 

 had been soaked. Sapwood and heartwood 

 samples of both healthy and diseased trees 

 were tested separately'. The water in 

 which the wood had been soaked, and 

 which contained the water-soluble materi- 

 als of the wood, is referred to below as 

 leach. 



All analyses of sap and leach were run 

 in duplicate and most of them were re- 

 peated two or more times. Ash of the sap 

 of diseased elms was obtained by evaporat- 

 ing the liquid and burning out the organic 

 material over low heat. This ash was re- 

 suspended in distilled water and used as 

 a test material. Also, filtrate of the ash 

 suspension was used as a test material. 



The sap — untreated, filtered, and fil- 

 tered and autoclaved — and the ash suspen- 

 sion filtrate contained a moderate amount 

 of phosphate. In the ash suspension, phos- 

 phate was abundant. Only small amounts 

 of phosphate were present in the leaches 

 from wetwood and healthy heartwood. 

 Potassium was abundant in the sap — un- 

 treated, filtered, and filtered and auto- 

 claved — and in the ash suspension. There 

 was possibly a trace of potassium in the 

 leach from wetwood tissue but none in 

 the leaches from healthy sapwood and 

 heartwood. Magnesium was not present 

 in any materials tested except for possibly 

 a trace in the ash suspension. No nitrites 

 were found in sap from wetwood tissues 

 or in the leach from healthy heartwood. 

 There appeared to be traces of nitrites in 

 the leaches from healthy sapwood and 

 from wetwood tissues. In our analyses, 

 no calcium, chlorides, copper, iron, man- 

 ganese, zinc, nitrates, ammonia, starch, 

 indole or erythrodextrin were found in any 

 of the materials tested. The ash suspension 

 contained carbonates but it did not contain 

 bicarbonates or hydroxides. It would seem 

 from this fact that potassium and phos- 

 phorus were present as carbonates in the 

 materials tested. 



No reducing sugars were detected in 

 sap or in the leaches from wetwood tissues, 

 healthy sapwood or healthy heartwood. 

 There appeared to be traces of reducing 



