Relationship of Fall Watering Practice to Winter Injury of Conifers

Article Figures & Data

Table 1.

Water content of arborvitae tissue from plants subjected to different soil water treatments in Experiment 1 (1977-78 study).

Water treatment (ml water/pot)	Water content percentage (fresh wt—dry wt./fresh wt.×100)
Date evaluated
	8/29	9/10	9/26	10/6	10/17	10/27	11/4	11/11	11/22	12/2	2/2 7	4/14
400	69.0	64.0	66.3	63.7	60.7	65.3	60.0	55.3	58.5	56.1	54.9	55.5
100	60.0	59.7	60.3	59.7	58.7	63.0	60.3	58.3	57.7	57.7	55.0	55.9
100—400 Nov. 2	—	—	—	—	—	—	59.3	57.3	59.3	59.1	54.6	55.5
50	59.7	59.3	59.3	59.0	58.7	61.3	60.3	60.4	58.0	58.0	54.5	54.7
50—400 Nov. 2	—						61.3	59.7	60.4	59.7	52.1	57.4

Table 2.

Water content of arborvitae tissues from plants subjected to different soil water treatments in Experiment 2 (1978-79 study).

Water treatment (ml water/pot)	Water content percentage (fresh wt.—dry wt./fresh wt.×100)
Date evaluated
	9/1	9/27	10/6	10/13	10/23	10/31	11/7	12/12
400	65.5	60.0	61.0	59.8	60.0	54.4	56.3	53.3
100	59.9	56.5	54.7	54.3	57.9	54.1	52.9	51.0
100-400 Oct. 1	—	—	59.1	58.2	59.6	55.3	55.6	55.4
100-400 Oct. 15	—	—	—	—	59.7	55.7	56.3	53.9
100-400 Nov. 1	—	—	—	—	—	—	54.9	53.7
50	54.9	57.2	54.5	54.8	53.1	52.2	50.8	47.4
50-400 Oct. 1	—	—	52.1	55.1	56.8	55.3	56.0	53.2
50-400 Oct. 15	—	—	—	—	59.3	55.5	55.1	53.9
50-400 Nov. 1	—	—	—	—	—	—	56.5	52.7

Table 3.

Pressure chamber readings of water potential of arborvitae plants subjected to different soil water conditions. Experiment 2 (1978-79 study)

Table 4.

Cold hardiness level of arborvitae subjected to different soil water conditions

Cold hardiness level (expressed as lowest temperature ° C tolerated without severe injury)
Water Treatment ml/pot	Experiment 1 (1977 study)				Experiment 2 (1978 study)
Date tested
	10/6	10/21	11/2	10/2	10/16	11/3	11/13	12/14
400	–13	–18	–24	–9	–18	–27	—36^{^z}	-57^{^z}
100	–17	–18	–27	–12	–24	–24	–33	–57^{^z}
50	–10	–18	–24	–9	–18	–24	—36^{^z}	–48^{^y}
100-400 Oct. 1	—			—	–24	–27	–36^{^z}	–57^{^z}
100-400 Oct. 15					—	–24	–36	–57^{^z}
100-400 Nov. 1				—	—	—	-36^{^z}	-57^{^z}
50-400 Oct. 1				—	–18	–21	–36^{^z}	–57^{^z}
50-400 Oct. 15				—	—	–18	–36^{^z}	–57^{^z}
50-400 Nov. 1					—	—	–33	— 51^{^x}

Tab Average visual rating of Injury of arborvitae subjected to different soil water treatments

Soil water treatment (ml/pot)	Average visual rating of injury^{^z}
	Experiment 1 (1977-78 study)		Experiment 2 (1978-79 study)
	5/10/78	12/12/78	5/15/79
400	1.6	1.6	1.4
100	2.0	2.0	1.4
50	3.2	3.4	3.8
100-400 Oct. 1	—	1.4	1.4
100-400 Oct. 15	—	1.6	2.0
100-400 Nov. 1^{^z}	2.2	1.6	2.0
50-400 Oct. 1		3.2	3.0
50-400 Oct. 15	—	3.4	3.2
50-400 Nov. 1^{^y}	2.8	3.8	3.4

↵^z Code of visual ratings: 1 = dark green foliage —-no visual signs of injury; 2 = foliage lacks lustre — some tissue browning (10% brown); 3 = Moderate foliage injury 10-40% foliage brown; 4 = severe foliage injury — 40% foliage brown; and 5 = plants dead.
↵^y plants rewatered on November 2 in 1977-78 study