scholarly journals FERTILIZER EFFECTS ON EARLY GROWTH AND YIELD OF 'HAMLIN' ORANGE TREES

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 595b-595
Author(s):  
Thomas A. Obreza ◽  
Robert E. Rouse
Keyword(s):  
Maximum Rate ◽  
Fruit Yield ◽  
Tree Canopy ◽  
Poncirus Trifoliata ◽  
Soluble Solids ◽  
Growth And Yield ◽  
Fertilizer Rate ◽  
Cross Sectional ◽  
Canopy Volume ◽  
K Fertilizer

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.

scholarly journals Fertilizer Effects on Early Growth and Yield of `Hamlin' Orange Trees

HortScience ◽  
1993 ◽  
Vol 28 (2) ◽  
pp. 111-114 ◽  
Author(s):  
Thomas A. Obreza ◽  
Robert E. Rouse
Keyword(s):  
Maximum Rate ◽  
Fruit Yield ◽  
Tree Canopy ◽  
Water Soluble ◽  
Soluble Solids ◽  
Growth And Yield ◽  
Fertilizer Rate ◽  
Cross Sectional ◽  
Solids Concentration ◽  
Canopy Volume

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.

Growth and yield of clonal guavas in south-eastern Queensland

1986 ◽  
Vol 26 (5) ◽  
pp. 619
Author(s):  
KR Chapman ◽  
B Paxton ◽  
DH Maggs
Keyword(s):  
Fruit Size ◽  
Tree Height ◽  
Tree Canopy ◽  
Tree Size ◽  
Growth And Yield ◽  
Marketable Yield ◽  
Cross Sectional ◽  
South Eastern ◽  
Canopy Volume ◽  
Highly Correlated

Five processing guava clones (GA6- 1, GA7- 12, GA8-30, GA9-35, GA11-56) were tested over 3 cropping years at Nambour, in coastal south-eastern Queensland. Mean marketable yield for the first crop at 2 years of age was 45 kg/tree or 36.23 t/ha at a density of 805 trees/ha. GA11-56, the most acceptable clone for processing, also gave the highest marketable yields of 627, 71.65 and 72.53 t/ha for the first 3 crops. Yield per unit cross sectional area of trunk was a more simple and useful index of yield efficiency than more complex parameters including a fruitfulness index and multiple regressions with yield of north-south canopy spread, number of primary branches and combinations of these and trunk girth. Similarly, trunk - - girth provided at least as good an estimate of tree size as the vigour index. Tree dimension measurements which included east-west canopy spread, north-south canopy spread, tree height, stem height, number of primary branches, crown height, crown radius, tree canopy volume, canopy surface area and an index of crown weight provided no consistent indication of tree size. They were not highly correlated with either accumulated or final yield of the guava. The GA11-56 clone because of its yield, fruit size and other desirable processing characteristics was the only clone that could be recommended for commercial plantings.

scholarly journals Orchard Groundcover Management Impacts on Apple Tree Growth and Yield, and Nutrient Availability and Uptake

1994 ◽  
Vol 119 (2) ◽  
pp. 209-215 ◽  
Author(s):  
Ian A. Merwin ◽  
Warren C. Stiles
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Fruit Yield ◽  
Growth And Yield ◽  
Meadow Vole ◽  
Cross Sectional ◽  
Phytophthora Root Rot ◽  
K Fertilizer ◽  
Leaf N

This study compared various conventional and alternative orchard groundcover management systems (GMSs)—including a crownvetch “living mulch” (CNVCH), close-mowed (MWSOD) and chemically growth-regulated (GRSOD) sodgrasses, pre-emergence (NDPQT) and two widths of postemergence (GLY1.5 and GLY2.5) herbicides, hay-straw mulch (STMCH), and monthly rototillage (tilled)—during 6 years in a newly established apple (Malus domestica Borkh.) planting. Trunk cross-sectional area and fruit yield were higher in STMCH, GLY, and NDPQT, intermediate in tilled, and lower in GRSOD, MWSOD, and CNVCH treatments after 5 years. Despite N and K fertilizer applications, extractable soil N and leaf N concentrations were reduced under MWSOD and GRSOD, and soil K, P, and B concentrations were greater under STMCH. Leaf K concentrations were usually highest in STMCH trees, even when heavily cropped; leaf K declined below the sufficiency range in GLY, NDPQT, and tilled trees as they began to bear fruit. Leaf Ca was marginally deficient in all trees and was unaffected by GMS. Foliar Mn, Zn, and B concentrations declined rapidly in all treatments during 2 years without micronutrient fertilizers. Leaf Cu was higher in herbicide and tilled treatments where seasonal soil water content was intermediate (22% to 27%) and lower where soil was very wet or dry for most of the 1988 growing season. Multiple regression analysis indicated that leaf N and B and soil organic matter in 1990, and mean soil water content during the unusually dry Summer 1988, were the best predictors of fruit yield in 1990. Phytophthora root rot and meadow vole depredation were serious problems in STMCH and CNVCH trees. GMSs greatly affected tree establishment, nutrition, and yield; each system involves tradeoffs among important short- and long-term impacts on the orchard agroecosystem.

scholarly journals Effects of Fertilizer Rate and Form on Vegetative Growth and Yield of Southern Highbush Blueberry in Pine Bark Culture

2009 ◽  
Vol 19 (1) ◽  
pp. 152-157 ◽  
Author(s):  
J.G. Williamson ◽  
E.P. Miller
Keyword(s):  
Root Systems ◽  
Fruit Yield ◽  
Pine Bark ◽  
Growth And Yield ◽  
Highbush Blueberry ◽  
Fertilizer Rate ◽  
Liquid Fertilizer ◽  
Berry Weight ◽  
Canopy Volume ◽  
Southern Highbush

Growth and yield of ‘Misty’ and ‘Star’ southern highbush blueberry (Vaccinium corymbosum hybrid) plants that were grown in pine bark culture were evaluated under several rates of granular or liquid fertilizers. Granular fertilizer resulted in larger canopy volumes and slightly greater annual fruit yield than liquid fertilizer. In 2003 and 2004, canopy growth increased linearly as fertilizer rate increased up to the highest rate tested [81 g nitrogen (N), 11.8 g phosphorus (P), and 44.6 g potassium (K) per plant per year]. Similarly, a positive relationship was found for fruit yield and fertilizer rate during all 3 years. Berry yield was positively correlated with canopy size, and there was no relationship between fertilizer rate and berry yield per canopy volume, indicating that yield and canopy volume increased proportionally with increased fertilizer rate. Mean ‘Star’ berry weight was greater for granular fertilizer treatments than for liquid fertilizer treatments, but mean berry weight of ‘Misty’ was unaffected by fertilizer form. At the end of the experiment, visual examination of eight plants excavated by hand indicated that root systems of blueberry plants were primarily located in the pine bark layer with very few roots penetrating into the underlying soil. Limited water and nutrient holding capacities of pine bark, coupled with frequent irrigations to the shallow root systems in pine bark culture, probably resulted in considerable nutrient leaching and a high fertilizer requirement.

scholarly journals Effect of Organic Manures and Chemical Fertilizers on the Growth, Yield and Quality Traits of Summer Squash (Cucurbita pepo L.)” cv. Punjab ChappanKaddu

2021 ◽  
pp. 142-152
Author(s):  
Amandeep Kaur ◽  
Puja Rattan
Keyword(s):  
Cucurbita Pepo ◽  
Male Flower ◽  
Fruit Yield ◽  
Chemical Fertilizer ◽  
Soluble Solids ◽  
Growth And Yield ◽  
Recommended Dose ◽  
Chemical Fertilizers ◽  
Organic Manures ◽  
Summer Squash

The present investigation was conducted during 2019 at DAV University, Jalandhar, to find out the effect of organic manures and chemical fertilizers on the growth and yield of summer squash (Cucurbita pepo L.) cv. Punjab Chappan Kaddu. The experiment consisted of eleven treatments and three replications. Out of these, an application of 25% of the recommended dose of chemical fertilizer + vermi-compost 15t/ha (T8) had a beneficial effect on minimum days to the first female flower (74.67 days), minimum days to the first fruit set (76.33), minimum days to the first fruit harvest (78.33). The maximum plant height (122.85cm) was recorded in 25% of the recommended dose of chemical fertilizer + FYM 25t/ha (T5). 75% of the recommended dose of chemical fertilizer + EM (Effective Micro-organism) Bokashi 2.5q/ha (T9) resulted in minimum days to male flower appearance. The maximum sex ratio (0.38), was obtained with the application of 50% of the recommended dose of chemical fertilizer + EM Bokashi 3q/ha (T10). The maximum number of pickings (26) and number of fruit per plant (9.85) were obtained with the application of 50% of the recommended dose of chemical fertilizer + EM Bokashi 3q/ha (T10). The maximum fruit yield per plant (2.20 kg), fruit yield per plot (26.26 kg), fruit yield per ha (405.57q) were recorded with the application of 50% of the recommended dose of chemical fertilizer + vermi-compost 15t/ha (T7). The maximum Total Soluble Solids (TSS) (2.40B°) were recorded with the application of 75% of the recommended dose of chemical fertilizer + FYM 20t/ha (T3) while, the ascorbic acid was maximum (52.50 mg/100g) when 25% of the recommended dose of chemical fertilizer + vermi-compost 15t/ha (T8) were applied. The highest net returns and benefit: cost (4.5) were obtained when 50% of recommended dose of chemical fertilizer + FYM 25t/ha (T4) was applied.

scholarly journals ‘Ray Ruby’ Grapefruit Affected by Huanglongbing II. Planting Density, Soil, and Foliar Nutrient Management

HortScience ◽  
2020 ◽  
Vol 55 (9) ◽  
pp. 1420-1432
Author(s):  
Dinesh Phuyal ◽  
Thiago Assis Rodrigues Nogueira ◽  
Arun D. Jani ◽  
Davie M. Kadyampakeni ◽  
Kelly T. Morgan ◽  
...  
Keyword(s):  
Growth Parameters ◽  
Quantitative Polymerase Chain Reaction ◽  
High Density ◽  
Fruit Yield ◽  
Soluble Solids ◽  
Planting Density ◽  
Nutrient Concentrations ◽  
Trunk Diameter ◽  
Canopy Volume ◽  
Foliar Nutrient

Since the arrival of Huanglongbing (HLB) disease in Florida, several management approaches, including modification of orchard architecture design and nutritional therapy, have been explored. High-density plantings anticipate early economic returns from HLB-affected orchards. With no cure available for HLB, balanced nutrient application through soil and foliar spraying can mitigate the disease. A 2-year study was conducted to investigate the effects of three grapefruit (Citrus paradisi) planting densities [single-row (300 and 440 trees per ha), and double-row high-density (975 trees per ha)], two controlled-release fertilizer (CRF) blends, and foliar-applied micronutrients (FAM) (a blend of B, Mn, and Zn at 0, 1.5, 3, and 6 times the recommended rates) on grapefruit growth and fruit yield, physiological parameters, and foliar nutrient concentrations in an HLB-affected orchard. All the trees tested positive for HLB based on real-time quantitative polymerase chain reaction (qPCR) test. The highest planting density resulted in the lowest trunk diameter and canopy volume. Despite lower yield per tree in 2019–20, 975 trees per ha planting induced the greatest fruit and solid yields per ha. Also, the fruit produced from 975 trees per ha planting tended to be acidic with the deposition of more soluble solids. Use of CRF with higher micronutrients increased canopy volume with the expense of reduced fruit number in 2019–20. FAM did not affect cycle threshold (Ct) value and tree growth parameters. Fruit yield, photosynthesis rate, and stomatal conductance (gS) decreased, and all leaf nutrient concentrations except B increased in 2019–20 with all FAM rates tested. In conclusion, our study showed that high-density planting optimizes yield under HLB-endemic conditions. In addition, supplemental soil and foliar micronutrient application do not enhance yield of HLB-affected trees over a 2-year timeframe, warranting further research for confirmation of results.

scholarly journals Correlation of trunk cross sectional area with fruit yield, quality and leaf nutrient status in plum under North West Himalayan region of India

2019 ◽  
Vol 14 (1) ◽  
pp. 26-32
Author(s):  
Dinesh Kumar ◽  
K K Srivastava ◽  
S R Singh
Keyword(s):  
Nutrient Status ◽  
Reducing Sugar ◽  
Total Sugar ◽  
Cross Sectional Area ◽  
Fruit Yield ◽  
Sectional Area ◽  
Cross Sectional ◽  
North West ◽  
Canopy Volume ◽  
Yield Quality

An experiment was conducted to study the correlation of trunk cross sectional area (TCSA) with fruit yield, quality and leaf nutrient status in plum at ICAR-Central Institute for Temperate Horticulture, Srinagar, Jammu and Kashmir during 2013-14. The TCSA (110.45, 118.23, 123.45, 131.67, 139.25, 146.82, 152.37 and 161.26 cm2) was based on their trunk girth at 15 cm above the ground. Maximum canopy volume (23.14m3 and fruit number 128/ tree) were recorded when TCSA was highest (161.26cm2). Maximum fruit weight (58.85g) was recorded with 123.45cm2 TCSA. Fruit yield and productivity efficiency (59.47kg/ tree and 0.29kg/ cm2) were recorded with 152.37cm2 TCSA. Fruit size (47.45 x 44.12mm), pulp weight (57.54g) and pulp/stone ratio (43.92) were recorded with 123.45cm2 TCSA. Maximum TSS (19.450B), total sugar (13.98%) and reducing sugar (11.46%) were recorded with 161.26 cm2 TCSA. Non-reducing sugar (2.53%) was recorded with 118.23cm2 TCSA. Higher leaf nitrogen, phosphorus and potassium content (2.38, 0.19 and 1.95%) was observed with 161.26 cm2 TCSA. A positive and significant correlation was noticed between TCSA and canopy volume (0.995), fruit number (0.992), yield (0.968), pulp/stone ratio (0.903), TSS (0.977), total sugar (0.937), reducing sugar (0.920), non-reducing sugar (0.048), leaf N (0.971), leaf P (0.977) and leaf K (0.997) value in plum variety Santa Rosa under North West Himalayan region of India.

scholarly journals Impacts of Vaccinium arboreum Rootstocks on Vegetative Growth and Yield in Two Southern Highbush Blueberry Cultivars

HortScience ◽  
2020 ◽  
Vol 55 (1) ◽  
pp. 40-45
Author(s):  
Rebecca L. Darnell ◽  
Jeffrey G. Williamson ◽  
Deanna C. Bayo ◽  
Philip F. Harmon
Keyword(s):  
Pine Bark ◽  
Soluble Solids ◽  
Growth And Yield ◽  
Soil Conditions ◽  
Highbush Blueberry ◽  
Leaf Scorch ◽  
Canopy Volume ◽  
Southern Highbush ◽  
Vaccinium Arboreum ◽  
Bacterial Leaf Scorch

Vaccinium arboreum Marsh is a small tree adapted to low-organic matter soils and is one of the few ericaceous species that tolerates soil pH greater than 6.0. It has a deep root system and is more drought tolerant than cultivated blueberry. The use of V. arboreum as a rootstock for commercial blueberry production has been studied previously in young blueberry plantings. The objective of the current study was to expand on earlier work and evaluate growth, productivity, and tolerance to bacterial leaf scorch (Xylella fastidiosa) in established plantings of own-rooted vs. grafted southern highbush blueberry (SHB). Two field plantings of grafted and own-rooted ‘Meadowlark’ and ‘Farthing’ SHB were established in May 2011: one at the University of Florida–Institute of Food and Agricultural Sciences (UF-IFAS) Plant Science Research and Education Unit in Citra, FL, and the other at a commercial blueberry farm in Archer, FL. At both sites, four rootstock–scion combinations were grown in either pine bark-amended or nonamended soil. Canopy volume was greater in grafted compared with own-rooted ‘Meadowlark’ at both locations throughout the 4 years of the study (2015–18), whereas canopy volume in ‘Farthing’ was not consistently different. For both cultivars and both locations, canopy volume was greater on amended compared with nonamended soil. Although canopy growth was not consistently increased in the grafted compared with own-rooted plants, yield was greater in grafted plants of both cultivars at both locations. Cumulative yield over the 4 years was similar between grafted plants grown on both amended and nonamended soil, and was significantly greater than yield of own-rooted plants on nonamended soil, suggesting the use of this rootstock may decrease the requirement for pine bark amendment. In general, grafted plants produced larger berries, with no negative impacts on fruit soluble solids, titratable acidity, or firmness. ‘Meadowlark’—an SHB cultivar that exhibits high sensitivity to bacterial leaf scorch—displayed decreased development of bacterial leaf scorch symptoms when grafted onto V. arboreum compared with own-rooted plants. These results indicate the potential benefits of grafting SHB onto V. arboreum rootstock, particularly under marginal soil conditions. However, a complete economic analysis that also takes into account any differences in longevity between the two systems must be done to determine whether the benefits of using grafting are feasible financially for the grower.

scholarly journals Bell Pepper (Capsicum annum L.) Crop as Affected by Shade Level: Fruit Yield, Quality, and Postharvest Attributes, and Incidence of Phytophthora Blight (caused by Phytophthora capsici Leon.)

HortScience ◽  
2014 ◽  
Vol 49 (7) ◽  
pp. 891-900 ◽  
Author(s):  
Juan Carlos Díaz-Pérez
Keyword(s):  
Phytophthora Capsici ◽  
Net Photosynthesis ◽  
Fruit Yield ◽  
Bell Pepper ◽  
Soluble Solids ◽  
Growth And Yield ◽  
Phytophthora Blight ◽  
Ir Radiation ◽  
Capsicum Annum ◽  
Yield Quality

High temperatures can be detrimental to bell pepper, resulting in reduced fruit yield and increased incidences of fruit disorders such as sunscald and blossom-end rot. Shade nets are used to modify the crop microenvironment to improve plant growth and yield. The objectives were to evaluate effects of shade level on fruit yield, quality, and postharvest attributes and the incidence of Phytophthora blight (caused by Phytophthora capsici Leon.) in bell pepper (Capsicum annum L.). Experiments were conducted in Tifton, GA, in 2008 (with cv. Heritage) and 2009 and 2010 (with cvs. Camelot, Lafayette, Sirius, and Stiletto). Bell pepper plants were grown under shade levels of 0% (unshaded, as a control), 30%, 47%, 63%, and 80%. Shade level affected fruit yield, quality, postharvest attributes, and incidence of Phytophthora blight in plants. Total marketable (Fancy and US1) fruit yield increased with increasing shade level to a maximum at 35% shade and then decreased with further increments in shade level. Relative to unshaded plants, marketable yields were improved by 119% (2008) and 43% (2009 and 2010) at 35% shade level. US2 and cull (sunscald) fruit number declined with increasing shade level. ‘Camelot’ produced among the greatest number and yield of marketable fruit; ‘Sirius’ had the heaviest fruit and greatest number of culls. Fruit nitrogen (N), phosphorus (P), and potassium (K) concentrations increased and aluminum (Al), molybdenum (Mo), and nickel (Ni) decreased with increasing shade level. ‘Lafayette’ had the highest fruit concentration of N, calcium (Ca), sulfur (S), manganese (Mn), and zinc (Zn). Fruit soluble solids and percent of fruit dry weight decreased with increasing shade level; fruit water loss rate and bacterial soft rot incidence were unaffected. Fruit skin a* and b* values decreased in yellow fruit cultivars (‘Lafayette’ and ‘Sirius’) with increased shade level. Incidences of Phytophthora blight in plants and fruit sunscald decreased with shade level. Beneficial effects of shading on bell pepper were associated with a reduction in irradiation, air temperature, and soil temperature under shaded conditions resulting in amelioration of heat stress in the plants. Optimal shade level for maximal fruit yield was that which maximized the cooling effect resulting from reduction of infrared (IR) radiation and minimized the decrease in net photosynthesis resulting from reduction in photosynthetically active radiation (PAR).

scholarly journals Foliar Applications of Essential Nutrients on Growth and Yield of ‘Valencia’ Sweet Orange Infected with Huanglongbing

HortScience ◽  
2016 ◽  
Vol 51 (12) ◽  
pp. 1482-1493 ◽  
Author(s):  
Kelly T. Morgan ◽  
Robert E. Rouse ◽  
Robert C. Ebel
Keyword(s):  
Disease Incidence ◽  
Dry Weight ◽  
Poncirus Trifoliata ◽  
Growth And Yield ◽  
Nutrient Deficiencies ◽  
Citrus Paradisi ◽  
Essential Nutrients ◽  
Canopy Volume ◽  
Foliar Concentration ◽  
Citrus Trees

Huanglongbing (HLB) causes citrus root systems to decline, which in turn contributes to deficiencies of essential nutrients followed by decline of the canopy and yield. This study was conducted on a 6-year-old ‘Valencia’ [Citrus sinensis (L.) Osb.] on Swingle rootstock (Citrus paradisi Macf. × Poncirus trifoliata (L.) Raf.) trees in a commercial grove near Immokalee, FL, to evaluate the effects of foliar applications of selected essential nutrients (N, K, Mn, Zn, B, and Mg) on growth and productivity of citrus trees infected with Candidatus Liberibacter asiaticus (CLas), the pathogen putatively associated with HLB in Florida. Mn, Zn, B, and Mg were applied in all experiments to drip at 0×, 0.5×, 1.0×, and 2.0×/spray of what has been traditionally recommended in Florida to correct deficiencies. Treatments were applied foliarly 3×/year with the sprays occurring during each growth flush for 5 years (2010–14). Thus, the 0×, 0.5×, 1.0×, and 2.0×/spray treatments resulted in 0×, 1.5×, 3.0×, and 6.0×/year to correct deficiencies. MnS04 and ZnSO4 were applied with or without KNO3 and in separate experiments were compared with Mn3(PO3)2 and Zn3(PO3)2, respectively. Disease incidence, foliar nutrient content, canopy volume, and yield were measured. At the beginning of the experiment, foliar N, P, Ca, Mg, Cu, and B were in the sufficient range and K, Mn, Zn, and Fe were slightly low. Disease incidence was very high with 83% and 98% of trees testing positive for CLas in 2010 and 2014, respectively. Nutrients that are not mobile or have limited mobility in plants, namely Mn, Zn, and B, demonstrated an increase in foliar concentration immediately after spray and in the annual averages. Foliar K increased from the deficient to the sufficient level by KNO3 sprays, but the mobile nutrients N and Mg did not show an increase in foliar levels, indicating that intraplant transport occurs in the presence of HLB. Foliar KNO3 application had a stronger effect on growth than yield. Yield was most strongly affected by application of MnSO4 where yield of the 3×/year treatment was 45% higher than that of the unsprayed control, but yield declined by 25% for the 6×/year treatment. Yield within 95% of the maximum occurred with foliar Mn concentrations of 70–100 µg·g−1 dry weight when Mn was applied as MnSO4, which is at the high end of the traditionally recommended 25–100 µg·g−1 dry weight range. The phosphite form of Mn [Mn3(PO3)2] depressed yield by an average of 25% across all application concentrations. Zn, B, and Mg did not significantly impact yield. Canopy volume demonstrated concave relationships across application concentrations for MnSO4 and ZnSO4 without KNO3 and Mn3(PO3)2, Zn3(PO3)2, Boron, and MgSO4 with KNO3, with the minimum occurring near the 3×/year application concentration. These data indicate a complex interaction in the amount of nutrients applied and their corresponding effects on foliar concentration, growth, and yield for HLB-affected trees. The results of this study at least partially explain the current confusion among scientists and the commercial industry in how to manage nutrition of HLB-affected citrus trees. The traditionally recommended approaches to correcting nutrient deficiencies need to be reconsidered for citrus with HLB.

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