Timothy K. Hartz

Extension Specialist/Agronomist
Department of Plant Sciences
University of California
103 Asmundson Hall
Davis, CA  95616
email: tkhartz@ucdavis.edu


B.S.     Biology, Chemistry, Bowling Green State University, Ohio, 1973
M.S.    Horticulture, Colorado State University, 1977
Ph.D.   Horticulture, Virginia Polytechnic Institute and State University, 1980

Extension Specialist, University of California
Support the statewide vegetable industry through applied research and education programs.  Areas of emphasis include: drip irrigation and fertigation management, soil fertility, soil organic matter management, and non-point source pollution abatement.

Assistant General Manager, Chiquita Melon Packers (a subsidiary of Chiquita Brands).
Directed field production and postharvest handling for melon operations in Texas, California, and Mexico.  Served as technical consultant for related Chiquita subsidiaries throughout Latin America.

Extension Specialist, Texas A&M University
Provided technical support to the vegetable industry of the Rio Grande Valley through research and education programs.  Areas of emphasis included drip irrigation management, plasticulture techniques, and alternative pest control.

Instructor, Department of Horticulture, Virginia Polytechnic Institute and State University
            Taught undergraduate courses in plant propagation and greenhouse management.


Johnstone, P.R., T.K. Hartz and D.M. May.  2008.  Calcium fertigation ineffective at increasing fruit yield and quality of muskmelon and honeydew in California.  HortTechnology 18:685-689.

Hartz, T.K., P.R. Johnstone, R.F. Smith and M.D. Cahn.  2007.  Soil calcium status unrelated to tipburn of romaine lettuce.  HortScience 42:1681-1684.

Hartz, T.K., P.R. Johnstone, E. Williams and R.F. Smith.  2007.  Establishing lettuce leaf nutrient optimum ranges through DRIS analysis.  HortScience 42:143-146.

Hartz, T.K.  2006.  Vegetable production best management practices to minimize nutrient loss.  HortTechnology 16:398-403.

Hartz, T.K. and P.R. Johnstone.  2006.  Nitrogen availability from high-nitrogen-containing organic fertilizers.  HortTechnology 16:39-42.

Hartz, T.K. and P.R. Johnstone.  2006.  Relationship between soil phosphorus availability and phosphorus loss potential in runoff and drainage.  Comm. Soil Sci. Plant Anal. 37:1525-1536.

Hartz, T.K., P.R. Johnstone, E.M. Miyao and R.M. Davis.  2005.  Mustard cover crops are ineffective in suppressing soilborne disease or improving processing tomato yield.  HortScience 40:2016-2019.

Hartz, T.K., P.R. Johnstone, D.M. Francis and E. M. Miyao.  2005.  Processing tomato yield and fruit quality improved with potassium fertigation.  HortScience 40:1862-1867.

Johnstone, P.R., T.K. Hartz, M.D. Cahn and M.R. Johnstone.  2005.  Lettuce response to phosphorus fertilization in high phosphorus soils.  HortScience 40:1499-1503.

Johnstone, P.R., T.K. Hartz, M. LeStrange, J.J. Nunez and E.M. Miyao.  2005.  Managing fruit soluble solids with late-season deficit irrigation in drip-irrigated processing tomato production.  HortScience 40:1857-1861.

Hartz, T.K., P.R. Johnstone and J.J. Nunez.  2004.  Production environment and nitrogen fertility affect carrot cracking.  HortScience 40:611-615.

Hartz, T.K.  2003.  The assessment of soil and crop nutrient status in the development of efficient fertilizer recommendations.  Acta Hort. 627:231-240.

Martini, E.A., J.S. Buyer, D.C. Bryant, T.K. Hartz, and R.F. Dension.  2003.  Yield increases during organic transition: improving soil quality or increasing experience?  Field Crops Research 86:255-266.

Hartz, T.K.  2002.  Sustainable vegetable production in California: current status and future prospects.  HortScience 37:1015-1022.

Hartz, T.K., C. Giannini, R.O. Miller and E.M. Miyao.  2002.  Estimating soil K availability for processing tomato production.  Commun. Soil Sci. Plant Anal. 33:1389-1400.

Breschini, S.J. and T.K. Hartz.  2002.  Drip irrigation management affects celery yield and quality.  HortScience 37:894-897.

Breschini, S.J. and T.K. Hartz.  2002.  Presidedress soil nitrate testing reduces nitrogen fertilizer use and nitrate leaching hazard in lettuce production.  HortScience 37:1061-1064


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