Boron, Manganese, and Zinc Sorption and Leaf Uptake on Citrus Cultivated on a Sandy Soil

Solute fate in soil-plant continuum could either be soil or leaf uptake or leaching beyond the rooting zone. An adsorption coefficient (KD) is an important chemical property to describe the interaction between the solute and soil, affecting the solute movement in soils from one point to another. Boron (B), manganese (Mn), and zinc (Zn) uptake are evident in the leaves as a constituent of photosynthesis and other plant body-building mechanisms for growth and development. This study investigates the availability of micronutrients (B, Mn, and Zn) to citrus trees through modified application methods and rates. Leaf samples were collected from experimental plots arranged in a randomized complete block design, with 4 micronutrient treatments: control, foliar ×1, foliar ×2, and soil ×1. Boron, Mn, and Zn rates were 1.12, 10.08, and 5.60 kg ha−1, respectively. Composite soil samples were randomly collected at 5 points, and a 1-point adsorption study was conducted in 4 soil depths at an increment of 15 cm from the soil surface. Adsorption coefficient (KD) for Mn and B was 22 and 3 times higher at 0–15 cm than at soil depth of 15–60 cm. The adsorption coefficient (KD) for Zn was 2.5 times greater at 0–15 cm than 15–30 cm soil depth, while there was little or no sorption at 30–60 cm. Leaf Mn and Zn concentrations showed that foliar spray was 2 times higher than the soil application method, while B showed that the soil application method was 2 times higher than foliar application method for 2 seasons sampling events. Thus, the behavior of B, Mn, and Zn in the soil via adsorption coefficient (KD) reflects the availability of B, Mn, and Zn in the citrus leaves

Integrated Water, Nutrient, and Pesticide Management of Huanglongbing-Affected Sweet Oranges on Florida Sandy Soils—A Review

Citrus greening (huanglonbing (HLB)) disease has drastically reduced citrus fruit production in Florida over the last two decades. Scientists have developed sustainable nutrient management practices to live with the disease and continue fruit production. Best pesticide management practices have been devised to reduce the spread of HLB by Asian citrus psyllid (ACP). However, soil application of excessive nutrients and the use of soil drench application of pesticides to huanglongbing-infected citrus groves have been a serious environmental concern since the recent development of resistance to some pesticides. It is important to understand the consequences of applying pesticides and nutrients beyond the recommended application rates with an inappropriate method for citrus growth and development. Alternatively, foliar sprays of some nutrients proved effective to meet plants’ requirements, and foliar sprays of effective insecticide products could provide an adequate mode of action for group rotation to minimize insecticide resistance by ACP and other pests. Sustainability in citrus production systems should include best management practices that improve pesticide and nutrient efficiency by including the total maximum daily load exiting the grove to reduce pesticide and nutrient exports into waterbodies

Comparative Response of Huanglongbing-Affected Sweet Orange Trees to Nitrogen and Zinc Fertilization under Microsprinkler Irrigation

WOS: 000584155100001Nitrogen and micronutrients have a key role in many citrus plant enzyme reactions. Although enough micronutrients may be present in the soil, deficiency can develop due to soil depletion or the formation of insoluble compounds. the objectives of this study were to (1) determine the adsorption, distribution, and availability of Zn in a sandy soil; (2) compare the effectiveness of foliar and soil application methods of Zn on Huanglongbing [HLB] affected trees; (3) compare foliar application rates of Zn for HLB-affected trees; (4) determine the effect of N rates on yield, soil inorganic N distribution patterns, and tree growth parameters. Tree rows were supplied with three N rates of 168, 224 and 280 kg.N.ha(-1) and Zn at single and double recommended rates (recommended rate = 5.6 kg.Zn.ha(-1)) using foliar and soil application methods, in a split-plot experimental design. the results show that Zn concentration in the 0-15 cm soil depth was three times higher than the 30-45 and 45-60 cm soil depths during the study. An adsorption study revealed high Zn (K-D = 6.5) sorption coefficients at 0-15 cm soil depth, while 30-45 and 45-60 cm depths showed little sorption. Leaf Zn concentration for foliar spray was two times higher than the soil application method. A nitrogen level of 224 kg N ha(-1) improved canopy volume when compared to other N levels at the expense of reduced fruit weight. Foliar Zn application at 5.6 or 11.2 kg ha(-1) and N rate at 224 kg ha(-1) appear to be adequate for improving the performance of HLB-affected citrus trees.UF/IFAS Citrus Initiative; USDA NIFA Hatch Project [FLA-CRC-005593]; USDA MAC APHIS Agreement [AP19PPQST00C116]UF/IFAS Citrus Initiative, USDA NIFA Hatch Project No. FLA-CRC-005593 and USDA MAC APHIS Agreement No. AP19PPQS&T00C116