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- Author or Editor: Robert E. Rouse x
Tre-Hold, a commercially available sprout inhibitor containing ethylnaphthaleneacetate (NAA) for newly planted citrus trees in orchards was effective to prevent axillary bud growth on rootstock seedlings in the nursery. Tre-Hold applied at formulated concentration (1×), three-fourths (3/4×), and one-half (1/2×) to field-grown and container-grown greenhouse seedlings prevented sprouting. It was possible to control dormancy of individual buds without affecting adjacent buds. When applied to green citrus tissue, no phytotoxicity occurred. Full concentration of Tre-Hold was found to prevent scion bud healing of container-grown trees when the seedling was treated before budding. Application a few days before unwrapping and after the scion bud had healed did not affect bud healing or budling growth.
Juice quality from 4-year-old `Valencia' sweetorange (C. sinensis (L.) Osbeck) nucellar seedling clones VS-F-55-28-X-E, VS-SPB-1-14-19-X-E, old-line clones V-10-12-7-X-E, V-51-3-3-(STG-64G-4)-X-E, and `Rohde Red Valencia' RRV-472-3-26-(STG-31-18)-X-E, RRV-472-11-43-(STG-19-2)-X-E were compared for percentage juice per fruit, “Brix, acid, °Brix/acid ratio, soluble solids per standard 40.9 kg field box, and juice color score. Rootstocks were sour orange, Smooth Flat Seville, Cleopatra mandarin, Sun Chu Sha, calamandarin, Valencia seedling, P. myoliare × Ridge Pineapple X73-26, Duncan grapefruit, Carrizo, Benton and C-35 citranges, Swingle and F-80-18 citrumelos, Rangpur lime × Troyer citrange, P. trifoliata, and Vangasay lemon. V-10-12-7 had the most juice. RRV-472-11-43 had less acid than the other clones. VS-SPB-1-4-19 had highest ratio and RRV-472-3-26 the lowest. Soluble solids per box were lowest for RRV-472-3-26. Juice color score was highest for the two `Rohde Red Valencia' clones and lowest for V-10-12-7. Rootstock affected all juice quality factors except juice color score.
The Minolta chlorophyll meter SPAD-502 (Minolta Camera Company, 101 Williams Drive, NJ 07446, USA) has been found to be a quick, accurate, simple, and nondestructive way to determine chlorophyll content in citrus leaves and a standard curve had been developed. The SPAD-502 chlorophyll meter was used to measure chlorophyll content in citrus leaves of ten varieties on three rootstocks. Leaf mineral analysis was then determined on these leaves for N, P, K, Mg, Mn, Zn, Fe, Cu and Ca. Correlation r values were generally low and not significant for most nutrient elements but were highest for Fe and Ca. The relationship of leaf nutrient levels and chlorophyll meter readings are not understood. The usefulness of the SPAD chlorophyll meter for determining mineral content in citrus leaves is not yet known.
The citrus industry of the world is immense. Citrus-producing regions extend around the world and are located on both sides of the equator from approximately lat.35°N to lat.35°S. Citrus is produced under a wide variety of climatic conditions, including the humid tropics, arid subtropics, and intermediate climates. Citrus areas such as Florida, Texas, and Brazil have conditions intermediate to tropical and subtropical climates, whereas California, Arizona, Australia, and the Mediterranean countries have semiarid subtropical climates. The true size of this citrus industry is basically unknown because no documented statistics are available from numerous production areas that supply only local markets.
Controlled-release N (CRN) fertilizer is receiving interest as a possible nutrient best management practice (BMP) for Florida citrus production, but grower acceptance will be limited until cost decreases and familiarity with CRN materials increases. The objective of this study was to compare long-term citrus production resulting from N fertilizer programs containing isobutylidene diurea (IBDU) or methylene urea (MU) with a conventional water-soluble N fertilizer program to determine the magnitude of horticultural utility provided by CRN. We applied N to a newly planted `Hamlin' orange (Citrus sinensis L. Osbeck) orchard using three sources (100% ammonium nitrate (AN); a 50/50 mixture of AN/IBDU; a 60/40 mixture of AN/MU) at four rates (0.25, 0.5, 1.0, and 2.0 or 1.5 times the recommended annual rate) in factorial combination, and continued for 7 years. During this period, AN was applied 31 times vs. about 15 times for CRN-containing fertilizers. We measured fruit yield, juice quality, and total soluble solids (TSS) yield in years 4 through 7 and found that they generally were not affected by N source, especially when year-to-year variation was taken into account. In year 7, fruit and TSS yields of well-fertilized trees reached 153 and 9.2 kg/tree, respectively. Maximum 4-year cumulative fruit and TSS yields (486 and 27.6 kg/tree, respectively) occurred at an N rate of 200 kg/ha. Maximum juice quality occurred at 180 kg N/ha. We feel the CRN materials tested could be used successfully in a nutritional BMP program that would maintain high yields while potentially decreasing N loss to the environment.
Live oak (Quercus virginiana Mill.) traditionally has been propagated by seed because vegetative propagation has not been successful on a commercial scale (Flemer, 1962; Maynard and Bassuk, 1987; Morgan and McWilliams, 1976). However, as a result of seedling variability, live oaks offered for sale exhibited varied growth forms with variable quality.
A 2-year establishment study of perennial peanut (Arachis glabrata Benth.) planted in row middles of a 1-year-old citrus grove was initiated in southwest Florida. The effect of herbicide and fertilizer treatment combinations on perennial peanut density was measured. Treatments were Fluazifop-p-butyl (Fusilade 2000 1E) herbicide, K-Mag fertilizer, Fluazifop-p-butyl + K-Mag + N, and a nontreated control. Four replications were arranged in a randomized complete-block design. After 2 years, there were no significant differences in plant density between treatments (96% cover) and the control (89% cover). Applications of Fluazifop-p-butyl in years one and two were effective in controlling grassy weeds such as common bermudagrass [Cynodon dactylon (L.) Pers]. In this experiment. initiated 1 year after planting, perennial peanut without inputs (herbicide, fertilizer) was able to suppress common bermudagrass and to obtain a high level (89%) ground cover in 3 years (1991–94).
The growth response of young `Hamlin' orange (Citrus sinensis L. Osbeck) on Carrizo citrange (C. sinensis × Poncirus trifoliatu L. Raf.) trees to N-P-K fertilizer rates under field conditions in southwestern Florida was studied to determine the minimum fertilizer required to bring trees into maximum early production. The highest 8N-1.8P-6.6K fertilizer rate was 2.72,5.45, and 8.17 kg/tree in 1989,1990, and 1991, respectively. Additional fertilizer treatments equaled 50%, 25%, or 13% of the maximum rate. Fertilizer sources contained either all water-soluble N (applied more frequently) or 40% to 50% controlled-release N (applied less frequently), and they did not affect fruit yield or quality. The response of trunk cross-sectional area, tree canopy volume, and fruit yield to fertilizer rate was described by a linear plateau model. The model predicted a fruit yield of 22.6 kg/tree at the estimated critical fertilizer rate of 48% of maximum. Fruit yield at the 50% maximum rate averaged 21.2 kg/tree. As fertilizer rate increased, total soluble solids concentration (TSS) in juice and the TSS: acid ratio decreased, but weight per fruit and TSS per tree increased. A fruit yield >21 kg/31-month-old tree indicated vigorous growth.
The growth response of newly-planted 'Hamlin' orange (“Citrus sinensis L. Osbeck) on Carrizo citrange (C. sinensis × Poncirus trifoliata L. Raf.) trees to N-P-K fertilizer rates was studied to determine the minimum fertilizer required to bring trees into maximum early production. The highest fertilizer rate applied was 2.72, 5.45, and 8.17 kg·tree-1 of an 8-1.8-6.6 N-P-K fertilizer in 1989, 1990, and 1991, respectively. Additional fertilizer treatments equalled 50, 25, or 13% of the maximum rate. The response of trunk cross-sectional area, tree canopy volume, and fruit yield to fertilizer rate was described by a linear plateau model. The model predicted a fruit yield of 22.6 kg·tree-1 at the estimated critical rate of 48% of maximum. Fruit yield at 50% of maximum rate averaged 21.2 kg·tree. As fertilizer rate increased, total soluble solids (TSS) in juice and ratio (TSS:acid) decreased, but weight per fruit and TSS per tree increased. A fruit yield above 21 kg·tree-1 from 31-month-old trees was indicative of vigorous growth.