J. AMER. SOC. HORT. SCI. 118(6):910-915. 1993. Economic Analysis of Integrated Crop Management Practices of ‘Navel’ Oranges Etaferahu Takele 1 Soil and Environmental Sciences Department, University of California, Riverside, CA 92521 John A. Menge 2 Plant Pathology Department, University of California, Riverside, CA 92521 John E. Pehrson, Jr. 3 Lindcove Research and Extension Center, 22963 Carson Ave., Exeter, CA 9321 1 Jewell L. Meyer 4 Soil and Environmental Sciences Department, University of California, Riverside, CA 92521 Charles W. Coggins, Jr. 5 Botany and Plant Sciences Department, University of California, Riverside, CA 92521 Mary Lu Arpaia 6 Botany and Plant Sciences Department, University of California, Riverside, CA 92521 J. Daniel Hare 7 Entomology Department, University of California, Riverside, CA 92521 Darwin R. Atkin 8 Lindcove Research and Extension Center, 22943 Carson Ave., Exeter, CA 93211 Carol Adams 9 Statistics Department, University of California, Riverside, CA 92521 Additional index words. citrus sinensis, costs, integrated practices, productivity, returns Abstract. The effect of various integrated crop management practices on productivity (fruit yield, grade, and sire) and returns of ‘Washington Navel’ oranges [Citrus sinensis (L.) Osbeck] was determined in the San Joaquin Valley of California. Seventy-two combinations of treatments comprised of three irrigation levels [80%, 100%, and 120% evapotranspiration demand (ETc)], three N fertilizer levels (low, medium, and high based on 2.3%, 2.5%, and 2.7% leaf N, respectively), gibberellic acid (±), miticide (±), and fungicide-nematicide (±) were included in the analysis. Using a partial budgeting procedure, returns after costs were calculated for each treatment combiition. Costs of treatments, harvesting, packing, and processing were subtracted from the value of the crop. The value of the crop was calculated as the sum of returns of crop in each size and grade category. The overall result indicated that returns after costs were higher for the +fungicide- nematicide treatment and also were generally more with increased irrigation. The combination of 120% ETc, +fungicide- nematicide, medium or high N, -miticide, and -gibberellin showed the highest return of all treatment combinations. Second highest returns were obtained with high N or with miticide and gibberellin used together. Several extensive studies evaluating the effect of certain inputs on citrus growth and productivity have been conducted in Califor- nia and throughout the world. Some of those studies included irrigation (Marsh, 1973), fertilization (Embleton et al., 1978), and the use of various growth regulators (Coggins and Hield, 1968). Received for publication 13 July 1992. Accepted for publication 9 Apr. 1993. Supported in part by grants from the Univ. of California Statewide Integrated Pest Management Project and the Citrus Research Board. Mention of a trademark, proprietary product, or vendor does not constitute a guarantee or warranty of the product by the Univ. of California and does not imply its approval to the exclusion of other products or vendors that may be suitable. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this fact. 1 Extention farm management specialist. 2 Plant pathologist. However, no previous study has addressed the interactive effects of such treatments on productivity and grower returns. The objec- tive of this study was to do so in a ‘Washington Navel’ orange grove in which the interaction of contemporary grove management practices would be studied in one large-scale field experiment. We wanted to identify practices that maximize productivity and prof- its. We also calculated the effects of varied water prices on profitability when various management practices were used. Materials and Methods 3 Extension subtropical horticulture specialist, Retired. 4 Extension irrigation and soils specialist, Emeritus. 5 Plant physiologist. 6 Extension subtropical horticulture specialist. 7 Associate entomologist. 8 Staff research associate. 9 Principal statistician. A multidisciplinary, multiyear experiment was initiated in 1985 in the southern San Joaquin Valley of California on a 35-year-old parent ‘Washington Navel’ orange grove grown on rough lemon (Citrus jambhiri Lush) rootstock. The design was a randomized complete block with split-split-split plots consisting of a 3 × 2 × 2 × 3 × 2 factorial treatment design; i.e., three irrigation treatments [80%, 100%, and 120% of calculated daily evapotrans- piration demand (ETc)], two fungicide-nematicide treatments (±), two miticide treatments (±), three N fertilizer levels (N1 = low, N2 910 J. AMER. SOC. HORT. SCI. 118(6):910-915. 1993.