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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., Beede, R., Moore, J.M., Weinberger, G. and Menezes, J., Jr. 1983. Water use requirements and physiological response to water stress in pistachio. Annual report of the California Pistachio Commission, Crop Year 1982 - 1983, pgs. 53-57.

Goldhamer, D.A., Kjelgren, R., Beede, R., Moore, J.M., Menezes, J., Jr., and Weinberger, G. 1984. Physiological response of pistachio to severe water stress. Annual report of the California Pistachio Commission, Crop Year 1983 - 1984, pgs. 44-47.

Goldhamer, D.A., Kjelgren, R., Beede, R., Williams, L., Moore, M.J., Lane, J., Weinberger, G. and J. Menezes, 1985. Water use requirements of pistachio trees and response to water stress. Annual report of the California Pistachio Commission, Crop Year 1984 - 1985, pgs. 85-92.

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.

Goldhamer, D.A. 2005. Irrigation Management chapter of University of California Pistachio Production Manual (2005). Edited by L. Ferguson. pgs. 103-116.

Contributors:

Bob Beede
Dave Goldhamer
Terry Prichard
Blake Sanden
Larry Schwankl