Summer Irrigation of Established Oak Trees

Article Figures & Data

Table 1.

Tree condition

Area	Good-Fair	Serious decline or dead	Total trees	%Serious decline or dead
1988
Near irrigation	24	6	30	20.0
Non-irrigated	57	78	135	57.8
X² = 12.55
P < .01
1992
Near irrigation	22	8	30	26.7
Non-irrigated	37	98	135	72.6
X=² 20.58
P <.01

Table 2.

Drip irrigation trial

Irrigation	No new shoot growth	New shoot growth	Total trees	% New growth
4 weeks after irrigation
Drip	4	8	12	66.7
None	12	0	12	0
X² = 9.19
P <.01
5 weeks after irrigation
Drip	1	11	12	91.7
None	10	2	12	16.7
X² = 10.74
P <.01
Change in Vigor from 1988 to 1992
	Improved growth	No change or decline	Total trees	% no change
Drip	10	2	12	16.7
None	1	11	12	91.7
X² = 10.74
P <.01