Brent A. Holtz Ph.D.
2101 East Earhart Avenue, Suite 200
Stockton, CA 95206
Dr. Brent Holtz has been a Pomology Farm Advisor for the University of California for 27 years and County Director in San Joaquin County’s UC Cooperative Extension office for 10 years. Brent was raised on an almond ranch in the Northern San Joaquin Valley, attending schools in California: Modesto Junior College (A.A.), California Polytechnic State University, San Luis Obispo (B.S.), and earned both M.S. and Ph.D. degrees in Plant Pathology from the University of California, Berkeley. Following graduation in 1993, Dr. Holtz was a post-doctoral research associate with Dr. Themis Michailides at the University of California, Davis, before becoming a Pomology Farm Advisor in Madera County in 1994.
Brent's research and education programs are focused on growing almonds in a sustainable manner in the San Joaquin Valley of California, helping deciduous tree fruit growers in production agriculture find more environmentally friendly ways to produce their crops without compromising product quality or price. Brent is currently leading a research effort on whole almond orchard recycling where removed orchards are ground-up and incorporated into the soil to increase soil organic matter and soil water holding capacity. Brent is currently serving on San Joaquin County’s Agricultural Advisory Board and the San Joaquin Farm Bureau Federation Board of Directors.
- Finalist, Fresno, CA
Presented by Friends of Agriculture, 2002
- Proclamation of Achievement Award
Presented by Madera County Board of Supervisors, 2002
- National Achievement Award, Albuquerque, New Mexico,
Presented by National Association of County Agricultural Agents, 2001
SpecialtyPomology, deciduous tree fruits and nuts, plant pathology
Areas of Expertise (click to see all ANR academics with this expertise)
- Plants and Their Systems
- Plant Product Quality and Utility (Preharvest)
- Pathogens and Nematodes Affecting Plants
- Integrated Pest Management Systems
- Natural Resources and Environment
- Soil, Plant, Water, Nutrient Relationships
Emad Jahanzad, Brent A. Holtz,Cameron A. Zuber, David Doll, Kelsey M. Brewer, Sean Hogan, Amélie CM. Gaudin 2020. Orchard Recycling Improves Climate Change Adaptation and Mitigation Potential of Almond Production Systems. PLoS ONE 15(3): e0229588. https://doi.org/10.1371/journal.pone.0229588, is a peer-reviewed open access scientific journal published by the Public Library of Science, ISSN 1932-6203, LCCN 2006214532
G.T. Browne; N.J. Ott; A.T. Poret-Peterson; B. Lampinen; S.G. Metcalf; M.A. Yaghmour; B. Holtz; M. Culumber; G. Brar; and D. Doll. (2018). Anaerobic soil disinfestation as an alternative to soil fumigation for management of Prunus replant disease: effects on tree growth and yield. ISHS 2018, DOI 10.17660, Acta Horticulturae 1219: 287-294.
Holland, Leslie; Nouri, Mohamed Taieb; Crespo, Maria; Holtz, Brent; Yaghmour, Mohammad; Doll, David; Trouillas, Florent. (2018). First report of Collophora hispanica and C. paarla causing branch cankers of almond in California. Plant Disease. APS Journals. 102:8, 1663. 3/6/2018. https://doi.org/10.1094/PDIS-09-17-1518-PDN
Holtz, B.; Browne, G.T.; Doll, D.; Culumber, M.; Yaghmour, M.A.; Jahanzad, E.; Lampinen, B.; Gaudin., A. (2018). Whole almond orchard recycling and the effect on second generation tree growth, yield, light interception, and soil fertility. Acta Horticulturae. ISHS. 1219, 265-271.
Holtz, Brent A. (2017). Almond Orchard Recycling: The Slasher could improve soil fertility, Resource: engineering and technology for a sustainable world. Resource: engineering and technology for a sustainable world. American Society of Agricultural and Biological Engineers (ASABE). 24:4, 8-11. www.asabe.org/Resource
Haviland, David R.; Bentley, Walter J.; Siegel, Joel P; Holtz, Brent A.; Daane, Kent M.; Higbee, Bradley S.(2016). Navel Orangeworm and Obliquebanded Leafroller, in Pistachio Production Manual. University of California, Agriculture and Natural Resources, Publication.L. Ferguson and D. Haviland. 3545, 197-210.
Klonsky, Karen M.; DeMoura, Richard L.; Beede, Robert H.; Holtz, Brent A.; and Ferguson, Louise. (2016). Production Costs, in Pistachio Production Manual. University of California, Agriculture and Natural Resources, Publication.L. Ferguson and D. Haviland. 3545, pages 11-16.
Holtz, Brent A.; Parfitt, Dan E.; Ferguson, Louise (2016). Rootstock Production and Propagation, in Pistachio Production Manual. University of California, Agriculture and Natural Resources, Publication.L. Ferguson and D. Haviland. 3545, pages 75-82.
Holtz, Brent; Teviotdale, Beth L. (2016). Soilborne Diseases, in Pistachio Production Manual. University of California, Agriculture and Natural Resources, Publication.L. Ferguson and D. Haviland. 3545, 257-264.
Holtz, Brent A.; Doll, David A.; Browne, Greg. (2016). Whole orchard recycling and the effect on second generation tree growth, soil carbon, and fertility. Acta Horticulturae. International Society of Horticultural Science. 1112, 315-319.
Kallsen, C.E.; Parfitt, D.E.; and Holtz, B.A. (2014). Comparisons of bloom and harvest dates, alternate bearing index and and nut quality parameters of ‘Golden Hills’ and ‘Lost Hills’ pistachio cultivars to ‘Kerman.’ Proceedings of the sixth international symposium on Almonds and Pistachios. Acta Horticulturae. 1028, 279-284.
Holtz, Brent A.; Doll, David; Browne, Greg (2014). Orchard carbon and nutrient recycling. Proceedings of the sixth international symposium on Almonds and Pistachios. Acta Horticulturae. 1028, 347-350.
Browne, G.T.; Lampinen, B.D.; Holtz, B.A.; Doll, D.A; Upadhyaya, S.K.; Schmidt, L.S.; Bhat, R.G.; Udompetaikul, V.; Coates, R.W.; Hanson, B.D.; Klonsky, K.M.; Gao, S.; Wang, D.; Gerik, J.S.; and Johnson, R.S. (2013). Managing the almond and stone fruit replant disease complex with less soil fumigant. California Agriculture. 67:3545, 128-138. July-September. californiaagriculture.ucanr.edu
Parfitt, D.; Kallsen, C.; Holtz, B.; and Maranto, J. (2010). ‘Randy’ male pistachio. HortScience. 45:7, 1113–1115.
Kallsen, C.E.; Parfitt, D.E.; Maranto, J.; and Holtz, B.A. (2009). New pistachio varieties show promise for California cultivation. . California Agriculture. 63, 18-23. http://CaliforniaAgriculture.ucop.edu
Parfitt, D.; Kallsen, C.; Holtz, B.; and Maranto, J. (2008). “Lost Hills”: a new pistachio cultivar. Hort Science. 43:1, 247-249.
Adaskaveg, J.E.; Driever, G.F.; Gubler, W.D.; Forster, H.; Holtz, B.; Wade, L.M. (2008). Detection of Erwinia amylovora strains with reduced sensitivity to currently registered antibiotics and management of fire blight of pome fruits using Kasugamycin in integrated strategies. Acta Horticulturae. 793, 375-382. http://www.ishs.org
Holtz, B.A.; Martin-Duvall, T.; Adaskaveg, J.E.; and Lindow, S.E. (2008). Efficacy of bactericides and biological antagonists for the control of fire blight of apple in the San Joaquin Valley of California. Acta Horticulturae. 793, 445-450. http://www.ishs.org
Lindow, S.E.; Holtz, B.A.; Elkins, R.E. (2008). Improved biological control of fire blight of pear and apple by introduction of antagonistic bacteria to unopened flowers. Acta Horticulturae. 793, 451-456. http://www.ishs.org
Kallsen, C.; Parfitt, D.; and Holtz, B. (2007). Early differences in the intensity of alternate bearing among selected pistachio genotypes. Hort Science. 42:7, 1740-1743.
Adaskaveg, J.; Gubler, D.; Forster, H; Erickson, E.; Hoffman, E.; and Holtz, B. (2006). Evaluation of new bactericides for control of fire blight of pears caused by Erwinia amylovora. . Acta Horticulturae. 704, 277-282.
Holtz, B.A; and Hoffman, E.W. (2006). Predicting the occurrence of fire blight using leaf wetness in the San Joaquin Valley of California. Acta Horticulturae. 704, 187-190.
Bentley, W.; Pickel, C.; Hasey, J.; Coviello, R.; Viveros, M.; Holtz, B.; Andris, H.; Duncan, R.; Johnson, M.; and Van Sickle, G. (2006). Seasonal guide to environmentally responsible pest management practices in peaches and nectarines. UC ANR publication. 21625.
Ma, Z.; Yoshimura, M. A.; Holtz, B. A.; and Michailides, T. J. (2005). Characterization and PCR-based detection of benzimidazole-resistant isolates of Monilinia laxa in California. Pest Management Science. 61, 449-457.
Holtz, B. A.; Caesar-TonThat, and; T. McKenry, M.V. (2005). Wood chipping almond brush and its effect on soil and petiole nutrients, soil aggregation, water infiltration, and nematode and basidiomycete population, Options Méditerranénnes Série A., M. Cordeiro. 63, 247-256.
Holtz, B.A.; McKenry, M.V.; and Caesar-TonThat, T.C. 2004. Wood chipping almond brush and its effect on the almond rhizosphere, soil aggregation, and soil nutrients. Acta Horticulturae 638:127-134, ISSN:0567-7572, ISBN: 90 6605 707 6.
Holtz, B. A.; and Caesar-TonThat, T. (2004). Wood chipping almond brush to reduce air pollution as a sustainable alternative to burning that enhances soil quality and microbial diversity. Emerging Concepts in Plant Health Management. R. Caesar. Research Signpost. 159-185.
Holtz, B.; Lindow, S.E.; Teviotdale, B.L.; and Hoffman, E.W. 2002. Enhancing flower colonization of the biological control agent Pseudomonas fluorescens strain A506, and the efficacy of Apogee and Serenade, for fire blight control in the San Joaquin Valley of California. Acta Horticulturae 590:319-324.
Buchner, R.P.; Connell, J.H.; Holtz, B. A.; Olsen, J.L.; Olson, W.H.; and Reil, W. 2002. Leading edge of plant protection for walnut, almond, pecan, hazel, and pistachio production. HortTechnology 12(4):613-614.
Holtz, B. A. 2002. Pistachio Seedling blight. Pages 70-71 in Compendium of Nut Crop Diseases in Temperate Zones. Edited by Teviotdale, B. L., Michailides, T. J., and Pscheidt, J. W., Eds. American Phytopathological Society (APS) Press, St. Paul, MN.
Holtz, B. A. 2002. Plant protection for pistachio. HortTechnology 12(4):626-632.
Holtz, B.A.; Teviotdale, B.L.; and Hoffman, E.W. 2002. Predicting the occurrence of fire blight in the San Joaquin Valley of California. Acta Horticulturae 590:167-174.
Zeng, Q.; Brown, P. H.; and Holtz, B. A. 2001. Potassium fertilization affects soil K, leaf K concentration, and nut yield and quality of mature pistachio trees. HortScience 36(1):85-89.
Kallsen, C. E., Holtz, B. A., Villaruz, L., and Wylie, C. 2000. Leaf zinc and copper concentrations of mature pistachio trees in response to fertigation. HortTechnology 10(1):172-176.
Hong, C. X., Michailides, T. J., and Holtz, B. A. 2000. Mycoflora of stone fruit mummies in California orchards. Plant Dis. 84:417-422.
Holtz, B. A.; Teviotdale, B.; Turini, T. 1999. Comparison of models to predict the occurrence of fire blight in the San Joaquin Valley of California. Acta Horticulturae 489:437-444.
Zeng, D. Q.; Brown, P. H.; and Holtz, B. A. 1999. Effects of potassium fertilization on soil potassium distribution and balance in pistachio orchards. Better Crops 83(4):24-26, http://www.ppi-ppic.org.
Zeng, D. Q.; Brown, P. H.; and Holtz, B. A. (1999) Potassium fertilization and diagnostic criteria for pistachio trees. Better Crops 83(3):10-12, http://www.ppi-ppic.org.
Holtz, B. A.; Michailides, T. J.; and Hong, C. X. (1998). Development of apothecia from stone fruit infected and stromatized by Monilinia fructicola in California. Plant Dis. 82:1375-1380.
Hong, C. X.; Michailides, T. J.; and Holtz, B. A. 1998. Effects of wounding, inoculum density, and biological control agents on post harvest brown rot of stone fruits. Plant Dis. 82:1210-1216.
Klonsky, K.; Beede, B.; Ferguson, L.; Freeman, M.; Hendricks, L.; Holtz, B.; Kallsen, C.; Sibbett, S.; Livingston, P. (1998). Sample costs to establish a pistachio orchard and produce pistachios. Acta Horticulturae 470: 481-492.
Hong, C.X.; Holtz, B. A.; Morgan, D.P.; and Michailides, T. J. (1997). Significance of thinned fruit as a source of the secondary inoculum of Monilinia fructicola in California nectarine orchards. Plant Dis. 81:519-524.
Holtz, B.A.; Michailides, T.J.; Ferguson, L.; Hancock, J.G.; and Weinhold, A.R. (1996). First Report of Rhizoctonia solani (AG-4) on Pistachio Rootstock Seedlings in California. Plant Dis. 80(11):1303.
Free, S. J.; Holtz, B. A.; and Michailides, T. J. (1996). Mating behavior in field populations of Monilinia fructicola in California. Mycologia 88(2):208-211.
Holtz, B. A.; Karu, A. E.; and Weinhold, A. R. (1994). Enzyme immunoassay for detection of Thielaviopsis basicola. Phytopathology 84:977-983.
Holtz, B. A.; and Weinhold, A. R. (1994). Populations of Thielaviopsis basicola in San Joaquin Valley field soils and the relationship between inoculum density and disease severity of cotton seedlings. Plant Dis. 78:986-990.
California Agriculture Article Contributions
ANR Workgroup Associations
- Almond - Member
- Pest Management in ANR - Member
- Pistachio - Member
- Plant Pathology - Member
- Waste Management and Compost - Member