Nutrient removal by Valencia orange fruit from citrus orchards in Calqomia

C. K. LABANAUSKAS ' M. F. HANDY

TABLE 1. EFFECTS OF ROOTSTOCK ON ANNUAL YIELD AND These data show that relatively small sequent reduction in both fruit yield and PHYSICAL MEASUREMENTS OF VALENCIA ORANGES quality. Citrus growers, as a preventative amounts of nutrients applied to the soil Rootstocks* measure, tend to maintain their groves are removed by citrus fruit. The larger Sweet Rough Mean for1 amounts of these nutrients tied up in plant under fertility programs which are ex- Components orange lemon both rootstccks cessive. parts, particularly those in the leaf tissue, Wt of oranges/tree$ (kg) 90.4 96.0 97.2 Many papers have been published con- Number of fruit/tree 647.0 649.0 648.0 are eventually returned to the soil. For the Weiaht/fruit (9) 152.0 148.0 150.0 cerning nutritional requirements of pro- Equitorial diameter (cm) 6.4 6.3 6.4 most part, phosphorus, calcium, magne- Juice per fruit (ml) 85.0 77.0 81.0 ducing citrus trees, and from this work Dry weight of peel/fruit (9) 17.0 18.0 17.5 sium, zinc, manganese, copper, and iron leaf tissue analysis has gained wide ac- will be adsorbed by the soil particles and * Each value is a mean of 96 individual measurements. ceptance in determining an orchard's nu- t Each value is a mean of 192 individual measurements for 3 are not easily displaced from the soil. Con- tritional status. Several papers show the years, 1960, 1961, 1962. $ Field box of oranges weighs 24 kg. versely, these elements may not always be amounts of nutrients removed from an readily available to the plant. Availability orchard by citrus fruit, but the results of most of these cations to a plant is highly presented are averages of many cultivars year period. In June, 1960, 1961, and dependent upon soil hydrogen ion concen- and different locations. They show that 1962, 100 random fruits per tree were tration. Nitrogen compounds, being water potassium, calcium, nitrogen, and phos- measured for size. Eight outside fruits per phorus are elements removed in greatest tree from four trees per plot were picked solubLe, move readily in the soil and are quantity from the soil by citrus fruit. A -two fruits from each quadrant-using quite easily leached out, usually in the highly productive orange grove in Flor- a sizing ring to provide an annually rep- form of nitrates, although in some in- ida may annually remove as much as 28.6 resentative size common to all trees in the stances leaching losses of ammonium have kg (60.2 lb) of potassium, 36.3 kg (80 eight differential treatment experiment. been reported. It is imperative that nutri- lb) of nitrogen, 11.4 kg (25.0 lb) of cal- Fruits from each of the four trees in each ents be applied only as needed, since cium, 4.6 kg (10.3 lb) of magnesium, and plot were composited to make a sample larger applications may be considered as 2.3 kg (5.0 lb) of phosphorus per metric of 32 fruit. The primary objective in this "soil-polluting," and may find their way ton. experiment was the evaluation of effects into underground water supplies used for No published information is available of factorial foliar applications of manga- human consumption. showing the amounts of nutrients re- nese, zinc, and urea on yield and fruit moved from California orchards by Va- quality of Valencia oranges-and on N IMPORTANT FACTOR in efficient cit- lencia orange fruit. Such data have a nutrient concentrations in the leaves, A rus production is the maintenance significant potential for guidance in nu- peel, and juice. The physical and chemi- of an adequate nutrient balance in the trient management of citrus groves every- cal measurements of the fruit were used plant. Leaf chlorosis, premature defolia- where. Indiscriminate use (or oversup- to quantitate the nutrients removed by tion, fruit drop, and twig die-back may ply) of fertilizers may be thought to be the fruit from the soil. These data are be due to nutrient deficiencies. These of benefit to the plant, but it involves the presented in tables 1 and 2. physical abnormalities, any or all of risk of soil and water pollution. Under the specified field conditions at which may result from nutrient deficien- An experiment was established in Ven- this location, nitrogen, potassium, cal- cies in the plant, may contribute to a sub- tura County on a 20-year-old Valencia cium, phosphorus, and magnesium, were orange orchard, half on sweet orange and the elements removed in greatest quan- CALIFORNIA AGRICULTURE half on rough lemon rootstocks, using 64 tity (in that order) from the soil by Va- Progress Reports of Agricultural Research. published monthly by the University of Oali- four-tree plots per year during a three- lencia fruit Only small amounts of mi- fornia Division of Agricultural Sciences. William W. Paul ...... Manager TABLE 2. NUTRIENTS REMOVED BY VALENCIA ORANGE FRUIT Agricultural Publications Nutrient removed Jerry Lester ...... Editor Eleanore Browning ...... Assistant Editor Raatdack NP K Ca Ma Zn Mn Cu 8 Fe California Agriculture Mg/fruit$ Articles published herein may be republished or reprinted provided no advertisement for a Sweet orange* 268 27 286 114 25 0.19 0.10 0.08 1.10 0.39 commercial product is implied or imprinted. Rough lemon* 287 24 251 120 25 0.20 0.10 0.09 1.11 0.41 Please credit: University of California Avgt 277 25 268 117 25 0.19 0.10 0.08 1.10 0.39 Division of Agricultural Sciences. California Anriculturs will be sent free uuon Kg/metric ton fresh fruit$ request addkessed to: hditor Califofha 0.16 0.0013 0.0007 0.0005 0.0072 0.0025 Agrfculture, Agricultural Publikions, Uni- Sweet orange* 1.76 0.18 1.88 0.75 versity of California, Berkeley, California Rough lemon* 1.94 0.16 1.70 0.81 0.17 0.0013 0.0007 0.0006 0.0074 0.0028 adwn Avst 1.85 0.17 1.79 0.78 0.17 0.0013 0.0007 0.0005 0.0023 0.0026 To simplify the information in California Kg/haS Andculture it is sometimes necessarv to use trade names of-products or eiuipment. No Avg (both rootstockst) 4.00 42.90 18.72 4.00 0.030 0.016 0.005 0.176 0.062 endorsement of named products is intended - nor is criticism implied of similar products which are-not mentioned. * Each value based on 96 determinations. t Each value based on 192 determinations for 1960, 1961, 1962; 250 freedha. 141 $Conversion factors, metric to avoir.: mg to oz = 3.53 X 10-5; kg/metric ton to Ib/ton z 2.0; kg/ha to Ib/acre = 0.89.

CALI FOR N I A A G R I C U 1 T U RE, D E C EM B E R, 1 9 72 3 cronutrients were removed. The concen- tained in Florida show that higher C. K. Labanauskas is Professor of Hor- trations of nutrients in the fruit from this amounts of nitrogen, calcium, and boron, ticultural Sciences, and M. F. Handy is area were about the same magnitude as and lower amounts of zinc and manga- Staff Research Associate in the Depart- macro- and micro-nutrients found in the nese were removed by fruit in California. ment of Plant Sciences, College of Bio- peel and juice of fruit harvested from The amounts of phosphorus, potassium, logical and Agricultural Sciences, Uni- many other citrus-producing areas in magnesium, copper, and iron were about versity of California, Riverside. California. Based on fresh weight- of fruit, the same in California as those reported comparison of these values with those ob- in Florida.

Control of PYTHIUM ROOT ROT IN CARNATIONS

TABLE 1. CONTROL OF PYTHIUM VEXANS ON CARNATION PLANTS TABLE 2. EFFECT AND CONTROL OF PYTHIUM VEXANS AS MEASURED BY PLANT GROWTH ON CARNATION PLANTS

~ ~ ~~~ Rate of Tops Roots Rate of Equivalent Tops Roots Treatment Active Equivalent concentraticn Treatment concentration concentration Height Dry Wt Dry ,.,t Net Wt concentraticn Net wt Dry wt Dry wt inches gr gr gr gr gr gr Infested mix 46.1 27.33 5.96 .76 Infested mix PPM per cu ydt 45 6.7 1.00 Infested mix Infested mix + etharol 50 4% oz* 64 8.6 .91 + diaroben Infested + diazoben 25 1Va ozt: 64.5 9.1 1.55 weekly lOOppm 4oz/100gol 61.5 63.53 10.16 .74 Infested mix + diaroben 25 1% 01 72.5 10.8 1.71 Infested mix + PCNB +25 Vaoz + etharol 50 ppm 41/a or/cu yd 53.6 51.55 9.92 .79 Non-infested mix 68 9.8 1.26 Infested mix nraavlene 4I r--r,----- * 30% material. oxide 58.7 60.17 12.21 .B8 Based weight of moist planting mix at Ib/cu ft. t on 60 Non-infested mix 60.1 61.26 12.49 .95 t 35% material.

fected, this study was initiated to deter- cating the disease was controlled. A de- R. D. RAABE ' J. H. HURLIMANN mine the effect of this fungus on the crease in the size of the root system was growth of carnation plants. interpreted as the result of a slight tox- U.C. mix was infested with fungus icity from a high rate of application. Soil grown in pure culture on autoclaved treated with diazoben and diazoben plus These tests showed that when Pythium millet seed. Prior to use, some of the in- PCNB produced better plants than the vexans (isolated from carnation roots) was fested mix was treated with ethazol [5- non-infested mix, suggesting that there introduced into soil mixes, it reduced the ethoxy - 3 - trichloromethyl - 1,2,4-thiadia- may have been some contamination of the top growth and yield of Red Sim carna- zole] at 50 parts per million (ppm) active non-infested mix after planting. The fact ingredient, some was treated with diazo- that treatments with PCNB added to tions. No other symptoms were visible on ben [p- (dimethylamino) benzene-diazo diazoben resulted in better plants than the plants. Control measures using ethazol sodium sulfonate] at 25 ppm active and treatments with diazoben alone suggests as a preplant at 50 ppm, diazoben as a some was treated with diazoben plus that Rhizoctonia might also have been preplant at 25 ppm, or diazoben as a PCNB (pentachloronitro benzene) each introduced as a contaminant. drench at 100 ppm at weekly or biweekly at 25 ppm active. The mixes were put in Another experiment was then started intervals also gave control. The ethazol pots and 10 pots of each treatment were using similarly infested U.C. mix. Some preplant and diazoben drenches at weekly planted with Red Sim carnation plants. of thp infested mix was treated with or biweekly intervals may be slightly toxic. In addition, 10 plants were planted in ethazol at 50 ppm active. Some was fumi- Additional experiments on control are in infested mix to which no fungicide had gated with propylene oxide to kill the progress. been added, and 10 plants were planted fungus and in this way check the effect of in non-infested U.C. mix. Approximately the millet seed in the mix. Fifteen plants three months later, the plants were har- cach of Peterson's Red Sim were planted vested and the weights of the tops were in pots for each treatment. In addition, HE WATER MOLD FUNGI (Pythium determined. The tops and the roots were 30 plants were planted in infested mix and Phytophthora sp.) are known oven-dried and weighed. The results are and 15 oE these were drenched with toT attack many plants and cause damage given in table 1. ethazol weekly at the rate of 100 pprn ranging from slight injury to death of In this experiment it was found that all active. Fifteen were also grown in the in- the plants. Phytophthora sp. have been treated plants grew better tops than those fested mix, and 15 were grownirrnon- reported as damaging carnations but lit- grown in the infested mix. All of the root infested mix. After two months, no differ- tle has been reported regarding the ef- systems except the ethazol treatment were ences could be detected between the plants fects of infection of these plants by larger than those from the infested mix. growing in treated and non-treated mixes, Pythium sp. Since Pythium vexans has The tops of the plants grown in the mix except the plants in the latter were shorter been isolated from roots of carnation treated with ethazol weighed more than and did not have as many side branches plants not appearing to be adversely af- the the tops from the infested mix, indi- (see photo 1).At this time the heights

4 CALIFORNIA AGRICULTURE, DECEMBER, 1972