Pistachios
Irrigation management for Pistachio trees under drought conditions
Multiyear pistachio deficit irrigation research (Goldhamer and Beede, 2004) (Goldhamer, 2005) shows that significant irrigation water (approximately 10 inches during the season) can be saved by strategically irrigating pistachios.
Critical periods when pistachio should NOT be under-irrigated are: (1) from nut filling to hull slip (Stage 3: July 1 to Sept. 15 in the San Joaquin Valley), and (2) from bloom to end of shell expansion (Stage 1: Apr. 1 to May 15 in the San Joaquin Valley).
Deficit irrigation of pistachio CAN be practiced during the following periods: (1) 50% reduction in irrigation during shell hardening (Stage 2: May 16 - June 30 in the San Joaquin Valley), and (2) 70 - 75% reduction in irrigation during the postharvest period (Oct. 1 - Nov. 15 in the San Joaquin Valley).
San Joaquin Valley pistachio water use for normal and proposed Regulated Deficit Irrigation (RDI) regimes. Irrigation schedule early in the season must take into account stored winter rainfall.
Growth Stage |
Approximate Phenology |
Period | Reference Water Use ET (inches) |
Crop Coefficiant K |
Normal Crop ET In period (inches) |
Proposed RDI Level (%) |
Proposed RDI Crop ET (inches) |
Stage 1 |
Bloom
|
Apr. 1-15
|
2.36
|
.07
|
.17
|
100
|
.17
|
Leafout
|
Apr. 16-30
|
2.36
|
.43
|
1.01
|
100
|
1.01
|
|
Shell Expansion
|
May 1-15
|
3.19
|
.68
|
2.17
|
100
|
2.17
|
|
Stage 2 |
Shell Hardeining
|
May 16-31
|
3.40
|
.93
|
3.16
|
50
|
1.58
|
Shell Hardeining
|
June 1-15
|
3.84
|
1.09
|
4.19
|
50
|
2.09
|
|
Shell Hardeining
|
June 16-30
|
3.84
|
1.17
|
4.49
|
50
|
2.25
|
|
Stage 3 |
Nut Filling
|
July 1-15
|
4.13
|
1.19
|
4.92
|
100
|
4.92
|
Nut Filling
|
July 16-31
|
4.41
|
1.19
|
5.25
|
100
|
5.25
|
|
Nut Fill/Shell Split
|
Aug 1-15
|
3.54
|
1.19
|
4.21
|
100
|
4.21
|
|
Shell Splitting
|
Aug 16-31
|
3.78
|
1.12
|
4.23
|
100
|
4.23
|
|
Hull Slip
|
Sept 1-15
|
2.66
|
.99
|
2.63
|
100
|
2.63
|
|
Harvest
|
Sept 16-31
|
2.66
|
.87
|
2.31
|
25
|
.57
|
|
Postharvest |
Postharvest
|
Oct 1-15
|
1.71
|
.67
|
1.15
|
25
|
.29
|
Postharvest
|
Oct 16-31
|
1.83
|
.50
|
.91
|
25
|
.23
|
|
Postharvest
|
Nov 1-15
|
.8
|
.35
|
.28
|
25
|
.07
|
|
Totals (in.)
|
41.10
|
31.70
|
Source: Goldhammer, 2005
List of References
Goldhamer, D.A and B. H. Beede. 2004. Regulated deficit irrigation effects on yield, nut quality and water-use efficiency of mature pistachio trees. Journal of Horticultural Science & Biotechnology (2004) 79 (4) 538-545.
Contributors:
Bob Beede
Dave Goldhamer
Terry Prichard
Blake Sanden
Larry Schwankl