01 Jul 2021
Citrus Seedlings

Effects of Low pH on Photosynthesis, Related Physiological Parameters, and Nutrient Profiles of Citrus

Seedlings of “Xuegan” (Citrus sinensis) and “Sour pummelo” (Citrus grandis) were irrigated daily with a nutrient solution at a pH of 2.5, 3, 4, 5, or 6 for 9 months. Thereafter, the following responses were investigated: seedling growth; root, stem, and leaf concentrations of nutrient elements; leaf gas exchange, pigment concentration, ribulose-1,5-bisphosphate carboxylase/oxygenase activity and chlorophyll a fluorescence; relative water content, total soluble protein level, H2O2 production and electrolyte leakage in roots and leaves.

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01 Jul 2021

Citrus Fertilizer Management on Calcareous Soils

Soils in the south Florida flatwoods are underlain by calcium carbonate (CaCO3) that has accumulated through marine deposition over thousands of years. In most flatwoods, the CaCO3 lies below the profile and the overlying surface soil is usually acidic. However, CaCO3 also can occur at the surface, either naturally or as a result of earth-moving operations that have mixed the soil. The resultant soil is called calcareous. Soils also can become calcareous through long-term irrigation with water from the Floridan aquifer. This water contains small amounts of dissolved CaCO3 that can accumulate with time.

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29 Jun 2021

Manipulation of citrus flowering and fruiting by pruning

Selective pruning of citrus trees is needed to manipulate the partitioning of carbohydrates between various tree parts. In well-managed citrus orchards proper pruning practices will likely have the most significant impact on optimizing yield and fruit size. Inferior flowering wood is removed at specific phenological stages (as soon as possible after harvest in winter or as early in spring as possible). Smaller heading-back and thinning cuts are made throughout the canopy to weaken the trees’ regrowth vigor and to open trees to light, in an attempt to balance fruiting and regrowth.

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25 May 2021
HLB

CRISPR/Cas technology could enable early diagnosis of devastating citrus disease

Scientists from Penn State and the U.S. Department of Agriculture have developed a diagnostic test that enables early detection of Huanglongbing (HLB) by detecting the presence of the bacterium that causes the disease, i.e. Candidatus Liberibacter asiaticus (CLas). Early detection of CLas is vital in controlling the spread of HLB because trees that have been infected by CLas can serve as a disease reservoir for years before symptoms are visible.

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25 May 2021
HLB-antimicrobial peptide

A stable antimicrobial peptide with dual functions of treating and preventing citrus Huanglongbing

Researchers at the University of California have identified stable antimicrobial peptides (SAMPs) that can help to control the spread of Huanglongbing (HLB), also known as citrus greening disease. These peptides work in two ways: They inhibit the growth of Candidatus Liberibacter asiaticus (CLas) – the bacterium causing the disease – in trees that are HLB-positive and it helps to induce immunity in healthy trees.

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28 Apr 2021
Trapping 2021

Trapping for Asian Citrus Psyllid in Southern Africa: Feb / Mar 2021

The article describes how the presence of the Asian Citrus Psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Liviidae), in parts of Africa, most recently trapped in southwestern Tanzania and Kenya, is increasing the risk to citriculture in Southern Africa. ACP is an effective vector of Huanglongbing (HLB), which is a destructive citrus greening disease and is associated with the gram negative α-Proteobacteria Candidatus Liberibacter asiaticus (Las).

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28 Apr 2021
Orange Blossom

Effects of gibberellin treatment during flowering induction period on global gene expression and the transcription of flowering-control genes in Citrus buds

As we enter the flower induction stage different factor control the amount of flowering for the next season. Gibberellic acid (GA) is a strong inhibitor for the flowering genes in Citrus. The aim of the study was to determine to what length GA has got an influence. GA was applied on citrus bud and the genetics analyzed and more Leafy mRNA were transcribed in these buds.

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28 Apr 2021
Lane Late Citrus

Response of Navel Lane Late citrus trees to regulated deficit irrigation: Yield components and fruit composition

The aim of this study was to determine how regulated deficit irrigation (RDI) would affect the yield and fruit quality parameters at harvest for lane late Navel during the summer month / fruit growth phase 2. The final fruit size of all RDI treatments were smaller compared to the control, however, The first treatment of 50% ET0 had the best internal quality fruit with higher total soluble solids and acids. The latter treatment had a 19% yield reduction due to fruit size.

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25 Mar 2021
Citrus and Avocado

Timing Citrus and Avocado Foliar Nutrient Applications to Increase Fruit Set and Size

The goal of this research was to identify the role essential nutrients play in the physiology of tree crops, and then to apply the nutrient as a foliar fertilizer to stimulate a specific metabolic process at phenological stages when nutrient demand is high. This approach has proven successful. A single winter prebloom foliar application of nitrogen as low-biuret urea [0.16 kg N/tree (0.35 lb N/tree)] to 30-year-old ‘Washington’ navel orange (Citrus sinensis L. Osbeck) trees during flower initiation significantly increased yield and fruit number per tree for each of 3 consecutive years (P ≤ 0.05).

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25 Mar 2021
Citrus Greening

Citrus Greening: Management Strategies and their Economic Impact

Citrus huanglongbing (HLB), or greening, is the most destructive citrus disease worldwide and is threatening the sustainability of the industry in major citrus-growing regions. Various treatments have been proposed in the literature to manage the disease. We review such literature and conduct an economic analysis based on the reported treatment effects on fruit yield and quality to identify cost-effective management strategies.

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