. Bulletin. Natural history; Natural history. 434 Illinois Natural History Survey Bulletin Vol. 23. Art. 4 for the period November, 1942, to the end of February, 1944. The maximum pressure in this tree occurred in Septem- ber, 1943. Diseased elms under obser- vation in Hinsdale this same j'ear also produced maximum pressures in Septem- ber. The low pressure of pounds which occurred in June was recorded while the tree was fluxing through a crack in a branch crotch 3 feet above the gaugecock. To test the effect of drainage on fluxing, the gaugecock was left open from June 7 until the crotch
. Bulletin. Natural history; Natural history. 434 Illinois Natural History Survey Bulletin Vol. 23. Art. 4 for the period November, 1942, to the end of February, 1944. The maximum pressure in this tree occurred in Septem- ber, 1943. Diseased elms under obser- vation in Hinsdale this same j'ear also produced maximum pressures in Septem- ber. The low pressure of pounds which occurred in June was recorded while the tree was fluxing through a crack in a branch crotch 3 feet above the gaugecock. To test the effect of drainage on fluxing, the gaugecock was left open from June 7 until the crotch stopped fluxing on June 11. Then the gaugecock was closed, and fluxing began again on June 15. The gaugecock was reopened at once and the crotch stopped fluxing on June 17. There- after the gaugecock was kept closed, and the amount of fluxing was not sufficient from that time on to prevent the formation of callus. The crotch crack was sealed with callus on July 18, and fluxing ceased. Pressure in the trunk of this wetwood- infected tree was found to follow a diur- nal cycle as well as an annual cycle. Both pressure and air temperature readings dur- ing a period of 2 days and 1 night were re- corded on August 3—4 and August 12—13, 1943, fig. 29. On August 3, when the air temperature did not go much above the optimum temperature range for the wet- wood organism, the maximum pressure occurred at 1 :15 On August 4, 12 and 13, when the air temperature had risen above the optimum temperature for the organism by 9:00 , the maximum pressure occurred between 8 :30 and 11 :00 100. 100 wi 95 a. o UJ 90 uT 85 a. 80 75 70 READINGS AUGUST 3-4 PRESSURE IN THE TRUNK AIR TEMPERATURE Zl^..^^. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Illinois. Natural History Survey Division. Urbana, State of Illinois, Dept
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