424 



Illinois Natural History Survey Bulletin 



Vol. 23, Art. 4 



a sterilized cork stopper. Two of the 

 eight trees were used as checks. One check 

 tree was injected with 50 ml. of sterile 

 nutrient broth plus dextrose and the other 

 was untreated. 



Presence of infection of trunk wood in 

 the inoculated trees was determined by 

 culturing wood samples obtained with an 

 increment borer. One of the six trees 



puniila L., 2 to 3 inches d. b. h., grown in 

 a greenhouse pit, were used for a second 

 experiment which, like the first, was begun 

 in 1941. Three of these eight trees were 

 inoculated, each with 50 ml. of inoculum 

 — culture of fermenting bacteria in nutri- 

 ent broth plus dextrose — on October 10, 

 1941. This inoculum was injected by the 

 use of the hand syringe method described 



Fig. 23. — Apparatus used for injecting bacterial suspension and other materials into the 

 trunks of elms. The materia! is injected into the tree through a hole bored in the trunk to within 

 about 1 inch of the bark on the opposite side. 



inoculated with bacteria was sampled 

 April 21, 1942, two were sampled Novem- 

 ber 13, 1942, and three were sampled 

 April 10, 1943. The untreated tree was 

 sampled November 13, 1942, and the tree 

 injected with sterile nutrient broth plus 

 dextrose was sampled April 10, 1943. The 

 trunk wood samples obtained w^th an in- 

 crement borer from the six inoculated 

 trees showed dark brown streaks in the 

 heartwood. This discoloration was com- 

 parable to the streaking in elms naturally 

 infected wnth wetwood. Fermenting bac- 

 teria which produced both acid and gas in 

 nutrient broth plus dextrose were isolated 

 from the wetwood tissues of these six in- 

 oculated trees. These bacterial isolates 

 were similar to the original inoculum. The 

 untreated tree and the tree injected wnth 

 nutrient broth plus dextrose showed no 

 dark brown discoloration in the heart- 

 wood typical of wetwood. Fermenting 

 bacteria were not isolated from wood of 

 these two check trees. None of the eight 

 trees had wilted by February, 1945, when 

 they were removed from the greenhouse. 

 Siberian Elm, Greenhouse Inocu- 

 lations. — Eight Siberian elms, Ulmus 



above. As a check, another tree was in- 

 jected with nutrient broth plus dextrose. 

 The four remaining trees were untreated. 

 The four untreated trees and one of 

 the three inoculated trees were cut up and 

 examined on April 13, 1942. In three of 

 the four untreated trees, the 1938 and all 

 older wood was light brown, while the 



1939 and all younger wood was white. 

 Brown heartwood and white sapwood are 

 believed to be normal for healthy Siberian 

 elm. Bacteria were not isolated from the 

 trunk wood of these three trees. The 

 other untreated tree was fluxing through 

 cracks in crotches and through a crack 

 in the trunk. The trunkwood showed 

 normal w^hite 1942 and 1941 wood. The 



1940 wood was gray and water-soaked 

 and turned light brown upon exposure to 

 air. The 1939 and older wood was dark 

 brown and showed an infection of wet- 

 wood. Fermenting bacteria, which pro- 

 duced both gas and acid, were isolated 

 from the dark brown 1939 wood but not 

 from the grayish, water-soaked 1940 wood 

 or the white 1941 and "1942 wood. 



The inoculated tree which was exam- 

 ined on April 13, 1942, had normal white 



