California Agriculture
California Agriculture
California Agriculture
University of California
California Agriculture

R. Scott Johnson Ph.D.

Photo of R. Scott Johnson Ph.D.
CE Pomologist, Emeritus
Kearney Agricultural Research & Extension Center
9240 S. Riverbend Ave.
Parlier, CA 93648 Create VCard

Also in:
Department of Plant Sciences



B.S., Biology, University of Utah, SLC, UT, 1977
Ph.D., Pomology, Cornell University, Ithaca, NY, 1982

Research Statement

I am the Extension Specialist for apples, kiwifruit, fresh shipping peaches, nectarines and plums. My responsibilities include the coordination of research and extension activities for these commodities by acting as a liaison between Farm Advisors and the Pomology Department and between the fresh fruit industry and the University of California.

My research has focused on improving the efficiency of cultural practices in stone fruit production. Under this general objective are four areas that I have concentrated on:

1. Reduction of tree size with dwarfing rootstocks, pruning  and other cultural practices.

2. Fertilization strategies (nitrogen, zinc and other nutrients) for good fruit size and quality and minimal environmental contamination.

3. Irrigation management to maximize productivity and fruit quality but conserve water when possible.

4. Thinning strategies including chemical and mechanical approaches and studies of fruit growth physiology.

The objective of all these studies is to improve the efficiency of a grower's operations by reducing his inputs of labor, fertilizer and water without adversely affecting yield and fruit quality.


Irrigation, fertilization, fruit thinning, rootstocks and fruit growth of peach, plum, nectarine, apple and kiwifruit; Davis campus specialist

Areas of Expertise (click to see all ANR academics with this expertise)


Peer Reviewed

  • Johnson, S.; Andersen, R.; Autio, W.; Beckman, T.; Black, B.; Byers, P.; Cline, J.; Chavez-Gonzalez, C.; Cowgill, W.; Godin, R.; Greene, G.; Kaps, M.; Kamas, J.; Larsen, H.; Lindstrom, T.; Miller, D.; Newell, M.; Ophardt, D.; Ouellette, D.; Parra-Quezada, R.; Pokharel, R.; Reighard, G.; Robinson, T.; Schupp, J.; Stein, L.; Taylor, K.; Walsh, C.; Ward, D.; Warmund, M.; Whiting, M. (2011). "Performance of the 2002 NC-140 Cooperative Peach Rootstock Planting." Journal of the American Pomological Society 65(1): 17-25.
  • Johnson, S.; Newell, M.; Reighard, G. L.; Robinson, T. L.; Taylor, K.; Ward, D. (2011). "Weather conditions affect fruit, harvest date and soluble solids content of 'Cresthaven' peaches." Acta Horticulturae 903: 1063-1068.
  • Baugher, T. Auxt; Schupp, J.; Ellis, K.; Remcheck, J.; Winzeler, E.; Duncan, R.; Johnson, S.; Lewis, K.; Reighard, G.; Henderson, G.; Norton, M.; Dhaddey, A.; Heinemann, P. (2010). "String Blossom Thinner Designed for Variable Tree Forms Increases Crop Load Management Efficiency in Trials in Four United States Peach-growing Regions." Horttechnology 20(2): 409-414.
  • Johnson, S.; Phene, B.C. (2008). "Fruit quality disorders in an early maturing peach cultivar caused by postharvest water stress." Acta Horticulturae 792: 385-390.
  • Bassi, D.; Layne, D. R. (2008). Nutrient and water requirements of peach trees. The Peach: Botany, Production and Uses. Oxfordshire, UK, CAB International.: 303-331.
  • Lopez, Gerardo; Johnson, R. Scott; DeJong, Theodore M. (2007). "High spring temperatures decrease peach fruit size." California Agriculture 61(1): 31-34.
  • Sanchez, E. E.; Weinbaum, S. A.; Johnson, R. S. (2006). "Comparative movement of labelled nitrogen and zinc in 1-year-old peach Prunus persica (L.) Batsch trees following late-season foliar application." Journal of Horticultural Science & Biotechnology 81(5): 839-844.
  • Johnson, R.S.; Andris, H.; Day, K.; Beede, R. (2006). "Using dormant shoots to determine the nutritional status of peach trees." Acta Horticulturae 721: 285-290.
  • Day, Kevin R.; Johnson, R. Scott; DeJong, Theodore M. (2005). "Orchard system configurations increase efficiency, improve profits in peaches and nectarines." California Agriculture 59(2): 75-79.
  • DeJong, Theodore M.; Johnson, R. Scott; Doyle, James F.; Ramming, David (2005). "Research yields size controlling rootstocks for peach production." California Agriculture 59(2): 80-83.
  • Johnson, R. Scott; Williams, Larry E.; Ayars, James E.; Trout, Tom J. (2005). "Weighing lysimeters aid study of water relations in tree and vine crops." California Agriculture 59(2): 133-136.
  • Johnson, R. Scott; Ayars, J. E.; Hsiao, Ted (2004). "Improving a model for predicting peach tree evapotranspiration." Acta Horticulturae 664: 341-346.
  • DeJong, T.; Ramming, D.; Johnson, S.; Doyle, J. (2004). Peach and nectarine rootstock named 'K146-43'. United States Plant Patent No. PP15,228. U.S.A. 2004.
  • DeJong, T.; Ramming, D.; Johnson, S.; Doyle, J. (2004). Peach and nectarine rootstock named 'P30-136'. United States Plant Patent No. PP15,225. U.S.A. 2004.
  • Ayars, J. E.; Johnson, R. S.; Phene, C. J.; Trout, T. J.; Clark, D. A.; Mead, R. M. (2003). "Water use by drip-irrigated late-season peaches." Irrigation Science 22(3-4): 187-194.
  • Johnson, R. Scott; Ayars, Jim; Hsaio, Ted (2002). "Modeling young peach tree evapotranspiration." Acta Horticulturae 584: 107-113.
  • Johnson, R. Scott; Rosecrance, Rich; Weinbaum, Steve; Andris, Harry; Wang, Jinzheng (2001). "Can we approach complete dependence on foliar-applied urea nitrogen in an early-maturing peach?" Journal of American Society for Horticultural Science 126(3): 364-370.
  • Johnson, R. Scott; Andris, Harry L. (2001). "Combining low biuret urea with foliar zinc sulfate sprays to fertilize peach and nectarine trees in the fall." Acta Horticulturae 564: 321-327.
  • Johnson, R. S.; Ayars, J.; Trout, T.; Mead, R.; Phene, C. (2000). "Crop coefficients for mature peach trees are well correlated with midday canopy light interception." Acta Horticulturae 537: 455-460.
  • Handley, D. F.; Johnson, R. S. (2000). "Late summer irrigation of water-stressed peach trees reduces fruit doubles and deep sutures." Hortscience 35(4): 771-771.
  • Perry, R.; Reighard, G.; D., Ferree.; J., Barden; Beckman, T.; Brown, G.; Cummins, J.; Durner, E.; Greene, G.; Johnson, S.; Layne, R.; Morrison, F.; Meyers, S.; Okie, W. R.; Rom, C.; Rom, R.; Taylor, B.; Walker, D.; Warmund, M.; Yu, K. (2000). "Performance of the 1984 NC-140 cooperative peach rootstock planting." Journal of American Pomological Society 54(1): 6-10.
  • Johnson, R. S.; Handley, D. F. (2000). "Using water stress to control vegetative growth and productivity of temperate fruit trees." Hortscience 35(6): 1048-1050.
  • Rosecrance, R. C.; Johnson, R. S.; Weinbaum, S. A. (1998). "Foliar uptake of urea-N by nectarine leaves: A reassessment." Hortscience 33(1): 158-158.
  • Rosecrance, R. C.; Johnson, R. S.; Weinbaum, S. A. (1998). "The effect of timing of post-harvest foliar urea sprays on nitrogen absorption and partitioning in peach and nectarine trees." Journal of Horticultural Science & Biotechnology 73(6): 856-861.
  • Daane, Kent M.; Johnson, R. Scott; Michailides, Themis J.; Crisosto, Carlos H.; Dlott, Jeff W.; Ramirez, Hugh T.; Yokota, Glenn Y. (1995). "Excess nitrogen raises nectarine susceptibility to disease and insects." California Agriculture 49(4): 13-18.
  • Johnson, R. S.; Handley, D. F.; Day, K. R. (1994). "Postharvest water stress of an early maturing plum." Journal of Horticultural Science 69(6): 1035-1041.
  • DeJong, Theodore M.; Day, Kevin R.; Doyle, James F.; Johnson, R. S. (1994). "The Kearney Agricultural Center perpendicular "V" (KAC-V) orchard system for peaches and nectarines." Horttechnology 4(4): 362-367.
  • Girona, J.; Mata, M.; Goldhamer, D. A.; Johnson, R. S.; Dejong, T. M. (1993). "Patterns of soil and tree water status and leaf functioning during regulated deficit irrigation scheduling in peach." Journal of the American Society for Horticultural Science 118(5): 580-586.
  • Weinbaum, Steven A.; Johnson, R. Scott; DeJong, Theodore M. (1992). "Causes and consequences of overfertilization in orchards." Horttechnology 2(1): 112-121.
  • Johnson, R. S.; Handley, D. F.; Dejong, T. M. (1992). "Long-term response of early maturing peach trees to postharvest water deficits." Journal of the American Society for Horticultural Science 117(6): 881-886.
  • Johnson, R. S.; Lakso, A. N. (1991). "Approaches to modeling light interception in orchards." Hortscience 26(8): 1002-1004.
  • Johnson, R. S.; Rasmussen, John M. (1990). "Peach thinning optimization model." Acta Horticulturae 276: 247-255.
  • Johnson, R. S.; Handley, D. F. (1989). "Thinning response of early, mid-season, and late-season peaches." Journal of the American Society for Horticultural Science 114(6): 852-855.

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