Ute Albrecht

• PhD
• Associate Professor, Plant Physiology at University of Florida

The devastating citrus disease Huanglongbing (HLB), associated with bacterial pathogens of the genus Candidatus Liberibacter, has spread across many citrus production areas worldwide causing devastating economic losses. In Florida, infection rates in most commercial citrus orchards approach 100 percent by the time trees are 3-4 years old. Most scio...

Huanglongbing (HLB) is one of the most destructive bacterial diseases of citrus. No resistant cultivars have been identified, although tolerance has been observed in the genus Poncirus and some of its hybrids with Citrus that are commonly used as rootstocks. In this study we exploited this tolerance by comparing five different tolerant hybrids with...

This study examines the effects of organic amendments and weed management on the nutritional status and the performance of young ‘Valencia’ sweet orange (Citrus sinensis) trees grafted on the rootstock US-802 (Citrus maxima × Poncirus trifoliata) in a commercial southwest Florida production environment.

This study aimed to evaluate the effect of combining cover crops and herbicide treatment on the performance of mature HLB-affected citrus trees.

The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is an invasive citrus pest that vectors the phloem-dwelling bacterium, Candidatus Liberibacter asiaticus (CLas), which is a putative causal agent of citrus greening disease known as Huanglongbing (HLB). In Florida, the D. citri–CLas pathosystem complex is at present consider...

Florida citrus production has declined by over 90% since the bacterial disease huanglongbing (HLB) was found in the state. In the absence of an effective cure, growers are adopting more frequent fertilization and irrigation practices to improve tree health and prolong the life span of their orchards. However, Florida’s soils under citrus production...

In the winter season, citrus nursery production faces challenges including shorter days, lower light levels, and lower temperatures that delay vegetative budbreak and scion shoot growth. With the goal of improving the production cycle in the citrus nursery, we investigated the effect of supplemental LED light on the production of bud-grafted citrus...

The use of individual protective covers (IPCs) to protect newly planted citrus trees from Huanglongbing (HLB) infection is being widely adopted in Florida, an HLB-endemic citrus-producing area. It is known that IPCs positively influence most horticultural traits, increasing tree growth, flush expansion, and leaf size, enabling trees to sustain bala...

Health and quality of the root system are imperative to ensure the successful establishment of a citrus tree after transplant from the nursery into the field. Containerized citrus production in enclosed nurseries restricts root growth and can result in root circling and intertwining. This may hinder root expansion and result in root girdling after...

The use of individual protective covers (IPCs) to protect newly planted citrus trees from HLB infection is being widely adopted in Florida, an HLB endemic citrus producing area. It is known that IPCs positively influence most horticultural traits, increasing tree growth, flush expansion, and leaf size enabling trees to sustain a balanced carbohydra...

Citrus is commercially propagated via grafting, which ensures trees have consistent fruit traits combined with favorable traits from the rootstock such as soil adaptability, vigor, and resistance to soil pathogens. Graft incompatibility can occur when the scion and rootstock are not able to form a permanent, healthy union. Understanding and prevent...

Trunk injection of antibiotics has re-emerged as a strategy to mitigate citrus huanglongbing (HLB), a devastating disease associated with the bacterium Candidatus Liberibacter asiaticus (CLas). Despite commercial adoption in Florida, no studies have examined how oxytetracycline (OTC) injection may impact active plant-associated microbial communitie...

In the original publication [...]

Huanglongbing (HLB), which is associated with the phloem-limited bacteria Candidatus Liberibacter asiaticus (CLas), is a devastating disease that affects citrus trees worldwide. Because of the pervasiveness of the bacteria and psyllid vector, the disease is considered endemic in Florida. Although the effects of CLas on tree growth and physiology ha...

Huanglongbing (HLB) is a major disease of citrus associated with phloem-limited bacteria in the genus Candidatus Liberibacter that affects all known citrus species and relatives, with many commercial cultivars being greatly damaged. Testing cultivar tolerance to HLB in field conditions is difficult because of the erratic spread of the bacteria, sci...

The biggest threat to the $9 billion citrus industry in Florida is the bacterial disease known as Huanglongbing (HLB) or citrus greening. The most common methods for applying liquid agrochemicals to manage HLB in agricultural fields are foliar sprays and soil drenches. These techniques are often accompanied by off-target losses and have not proven...

Huanglongbing (HLB), an important citrus disease, causes many physiological and anatomical changes such as phloem dysfunction, imbalance in carbohydrate partitioning, decrease in leaf chlorophyll, and nutritional imbalances in the affected trees, ultimately resulting in tree decline. In Florida, HLB is associated with phloem-limited bacteria Candid...

Key message Trunk injection causes injury to trees and best practices must be established for use of this technology to manage vascular diseases such as huanglongbing. Abstract Trunk injection is a technique for applying plant protection compounds that has demonstrated efficacy for management of huanglongbing (HLB), a bacterial disease which has d...

The bacterial pathogen associated with citrus huanglongbing (HLB) resides in the phloem of affected trees. The widespread abundance of the vector in Florida, the Asian citrus psyllid ( Diaphorina citri ), and the location of the pathogen in the tree vascular tissue limits the efficacy of foliar-applied therapies. Trunk injection is a crop protectio...

Background: While the rootstock genotype (belowground part of a plant) can impact rhizosphere microbial communities, few studies have examined the relationships between rootstock genotype-based recruitment of active rhizosphere bacterial communities and the availability of root nutrients for plant uptake. Rootstocks are developed to provide resist...

The citrus industry in Florida faces a destructive endemic disease, known as huanglongbing (HLB), associated with Candidatus Liberibacter asiaticus (CLas), a phloem-limited bacterium, and transmitted by the Asian citrus psyllid (ACP). Rootstocks are regarded as critical to keep citrus production commercially viable and help trees cope with the dise...

Huanglongbing (HLB, a.k.a. citrus greening disease) has reduced Florida citrus production and acreage substantially since its discovery in 2005. Most commercially important citrus scion cultivars such as sweet oranges are susceptible to the disease and no cure is available at present. This has increased the demand for HLB-tolerant rootstocks to ret...

Huanglongbing (HLB) is a devastating bacterial disease associated with Candidatus Liberibacter asiaticus. The location of the pathogen within the vasculature of the tree has left growers with limited options for the effective management of the disease. Trunk injection is a crop protection technique that applies therapeutics directly into the xylem...

Traditional foliar spray and soil drench applications of crop protection compounds have been ineffective at managing huanglongbing (HLB) in citrus. Trunk injection is a technique that delivers crop protection compounds directly into the tree vasculature, which optimizes compound availability while minimizing drift, runoff, and damage to non-target...

Trunk injection is a targeted delivery of pesticides, insecticides, nutrients, or other plant protection materials into the stem or trunk of woody plants as an alternative to spraying or soil drenching. Trunk injection has historically been used for disease and pest management of high-value forest tree species or ornamental plants when aerial appli...

Grapefruit (Citrus × paradisi) is the second most cultivated citrus species in Florida and the first in the Indian River District. In the past decades, citriculture has been exposed to one of the greatest challenges, huanglonbing (HLB). It is essential to understand the mechanisms involved on how cultivars respond to the environment and the uptake...

Nutrient assessment of plants, a key aspect of agricultural crop management and varietal development programs, traditionally is time demanding and labor-intensive. This study proposes a novel methodology to determine leaf nutrient concentrations of citrus trees by using unmanned aerial vehicle (UAV) multispectral imagery and artificial intelligence...

Grafting a scion onto a rootstock results in physical and physiological changes in plant growth and development, which can affect tree vigor, productivity, and tolerance to stress and disease. Huanglongbing (HLB) is one of the most destructive citrus diseases and has become endemic in Florida since its introduction in 2005. It is associated with th...

The devastating citrus disease huanglongbing (HLB) associated with the phloem-limited bacteria Candidatus Liberibacter asiaticus (CLas) has caused a more than 70% reduction in citrus production since its discovery in Florida in 2005. Most citrus scion cultivars are sensitive to HLB, whereas some cultivars used as rootstocks are tolerant. Using such...

This new 8-page article presents an overview on the use of trunk injection for the targeted delivery of protection materials to agricultural crops to manage pests and diseases. Different methods of injection are described along with the underlying plant physiological principles, possible implications on the tree, and other concerns and consideratio...

Citrus crops have a long history of cultivation as grafted trees on selected rootstock cultivars, but all current rootstocks have significant limitations and traditional methods of rootstock breeding take at least 2–3 decades to develop and field test new rootstocks. Citrus production in the United States, and other parts of the world, is impaired...

Following the discovery of Asian citrus psyllid (ACP) in 1998 and Huanglongbing (HLB) in 2005, this destructive disease associated with the phloem-limited bacterium Candidatus Liberibacter asiaticus (CLas) now affects most mature citrus trees in Florida. Despite the endemic presence of ACP and HLB, Florida citrus growers continue to plant new trees...

Psyllid exclusion is the most effective strategy to keep citrus trees free from HLB. Individual protective covers (IPCs) are a novel strategy based on psyllid exclusion of individual trees using a protective mesh bag. This new 3-page publication summarizes the knowledge we have accrued from our 3-year-long field studies using the IPC system and pro...

Key message Plant biostimulants did not improve citrus health and productivity in an HLB-endemic environment after two years, but fulvic acids increased concentrations of some nutrients and influenced the rhizosphere microbial community. Abstract Fibrous root loss is one of the main factors associated with citrus tree decline due to Huanglongbing...

Identifying and quantifying the number and size of stomata on leaf surfaces is useful for a wide range of plant ecophysiological studies, specifically those related to water-use efficiency of different plant species or agricultural crops. The time-consuming nature of manually counting and measuring stomata have limited the utility of manual methods...

Most of the commercially important citrus scion cultivars are susceptible to Huanglongbing (HLB), which is the most devastating disease the citrus industry has ever faced. Because the rootstock can influence the performance of the scion in various ways, including disease and pest tolerance, use of superior rootstocks can assist citrus growers with...

Huanglongbing (HLB) is a devastating disease of citrus that is found in most citrus production areas around the world. The bacterium associated with HLB resides in and damages the phloem, restricting the movement of photosynthates throughout the plant and leading to tree decline. Considerable root loss can be observed in affected trees even when fe...

Health, growth, fruit production, and fruit quality of citrus crops are severely affected by tree infection with Candidatus Liberibacter asiaticus (CLas) and subsequent development of the disease huanglongbing (HLB). The use of HLB-tolerant rootstocks is one strategy that is used to ameliorate the effects of HLB in commercial production. Although t...

Huanglongbing (HLB) is the most devastating citrus disease in the world. Almost all commercial citrus varieties are susceptible to the causal bacterium, Candidatus Liberibacter asiaticus (CLas), which is transmitted by the Asian citrus psyllid (ACP). Currently, there are no effective management strategies to control HLB. HLB‐tolerant traits have be...

Modern citrus nursery production makes use of potted-tree propagation in greenhouses. Supplemental lighting is one method by which nursery tree growth and profitability may be significantly improved, but limited specific information is available. Five replicated experiments were conducted to determine the utility and effects of increasing daylength...

There is increased interest by the agricultural industry in microbial amendments that leverage natural beneficial interactions between plants and soil microbes to improve crop production. However, translating fundamental knowledge from laboratory experiments into efficient field application often has mixed results, and there is less clarity about t...

This new 5-page article presents an overview of the use of antibiotics in agriculture. Several of the most severe bacterial diseases of tree fruit and other crops are discussed and their integrated management, which includes the use of antibiotics, is described. Antibiotic use for plant disease protection is compared with the use of antibiotics in...

The rootstock plays a large role in modern citrus production because of its influence on tolerance to adverse abiotic and biotic soil-borne stresses, and on the general horticultural characteristics of the grafted scion. In recent years, rootstock has received increased attention as a management strategy to alleviate the devastating effects of the...

Key message In a grafted citrus tree, the leaf and root metabolic composition and the response to the phloem-limited pathogenic bacterium Candidatus Liberibacter asiaticus are influenced by the rootstock. Abstract Eleven different citrus rootstock varieties were investigated for their influence on the grafted tree response to Candidatus Liberibact...

Six new hybrid rootstocks, ‘US-1279’, ‘US-1281’, ‘US-1282’, ‘US-1283’, ‘US-1284’, and ‘US-1516’, were released from the U.S. Department of Agriculture (USDA) citrus breeding program to provide improved tree tolerance to huanglongbing (HLB), the most destructive disease facing the citrus industry in the United States and many other parts of the worl...

Cilantro ( Coriandrum sativum L.), also called coriander, is an herbaceous, annual plant that is cultivated worldwide for its leaves and seeds. Cilantro has a strong propensity to bolt quickly in hot weather and under long-day (LD) conditions, which affects the flavor and renders the crop unmarketable. High incidence of preharvest bolting in open-f...

Huánglóngbìng (HLB), citrus greening, is one of the most destructive diseases of citrus plants worldwide. In North America, HLB is caused by the phloem-limited bacterium Candidatus Liberibacter asiaticus and is transmitted by the Asian citrus psyllid, Diaphorina citri. No cure exists at present, and the use of antibiotics for the control of HLB has...

The large number of different rootstock varieties currently available for citrus production in Florida is unprecedented. This new 4-page article, chapter 4 of the forthcoming UF/IFAS Citrus Nursery Production Guide, provides information on rootstock uses in Florida, rootstock propagation, and the impact of tissue culture, as well as factors to cons...

Commercially grown citrus trees are usually composed of two parts: 1) the scion, which is the aboveground portion of the tree that produces the fruit, and 2) the rootstock, which comprises the root system and the lower portion of the trunk. This new 4-page publication, chapter 6 of the forthcoming Citrus Nursery Production Guide, discusses three ki...

This 6-page fact sheet is part of the 2019–2020 Florida Citrus Production Guide. This chapter addresses the most important decisions that should be made before and immediately after planting and refers to other chapters with more detailed information. Generally, the most important factors before planting fall into site selection and grove planning...

When preparing for new planting or replanting, an important factor to consider is the choice of rootstock. Choosing the right rootstock and scion combination can result in higher economic returns without any additional cost. Rootstocks affect scion vigor, yield, fruit size and quality, and pest tolerance. However, tree growth, yield, and fruit qual...

The implementation of breeding methods requires the creation of a large and genetically diverse training population. Large-scale experiments are needed for the rapid acquisition of phenotypic data to explore the correlation between genomic and phenotypic information. Traditional sensing technologies for field surveys and field phenotyping rely on m...

This paper investigates the influences of several limiting factors on the performance of ground penetrating radar (GPR) in accurately detecting huanglongbing (HLB)-infected citrus roots and determining their main structural characteristics. First, single-factor experiments were conducted to evaluate GPR performance. The factors that were evaluated...

This new 4-page article provides an overview of a group of crop production materials termed “plant biostimulants,” which are frequently promoted as environment-friendly alternatives to chemical-based products. It explains their regulatory status and presents an overview of the most popular materials (e.g., beneficial fungi, seaweeds, and silicon) a...

Key message Rootstock variety influences leaf metabolic profiles in a grafted citrus tree, but influence also depends on the scion. Abstract Proper selection of rootstocks in tree fruit crops such as citrus is important for successful production. Despite a large number of commercially available rootstocks, studies have mostly been limited to basic...

Many factors need to be considered when preparing for new tree plantings. Careful planning and preparation is necessary to ensure success and reduced frustrations in the future. Site selection, rootstock and scion selection, planting density, quality of trees, tree planting, irrigation, nutrition, and disease control are all important factors that...

This 3-page fact sheet is part of the 2018–2019 Florida Citrus Production Guide. Written by Ute Albrecht, Fernando Alferez, and Mongi Zekri, and published by the Horticultural Sciences Department, July 2018. HS1308/HS1308: 2022–2023 Florida Citrus Production Guide: Rootstock and Scion Selection (ufl.edu)

Fresh-cut sweet basil ( Ocimum basilicum L.) is highly sensitive to low temperatures during postharvest storage. This study investigates whether preharvest foliar application of different concentrations of abscisic acid (ABA) can increase tolerance of the commercial basil varieties ‘Di Genova’ and ‘Nufar’ to chilling injury (CI) during postharvest...

Proper selection of rootstocks in tree fruit crops such as citrus is important for successful production. Despite a large number of commercially available rootstocks, studies have mostly been limited to basic horticultural observations. We used untargeted gas chromatography-time of flight-mass spectrometry (GC-TOF MS) based metabolomics to understa...

Huanglongbing (HLB) is the most destructive bacterial disease of citrus worldwide. While most citrus varieties are susceptible to HLB, Poncirus trifoliata, a close relative of Citrus, and some of its hybrids with Citrus are tolerant to HLB. No specific HLB tolerance genes have been identified in P. trifoliata but recent studies have shown that cons...

There are generally inadequate supplies of seed for the newest rootstocks to satisfy the growing demand for the propagation material to be used in commercial citrus nurseries. Consequently, rootstock propagation, which is traditionally by seed, now often makes use of alternative methods such as cuttings and tissue culture (TC). Propagation through...

This publication explains the different methods of citrus propagation and includes detailed descriptions and photographs of the grafting process and other principles of propagation.

When preparing for replanting, an important factor to consider is the choice of rootstock. Choosing the right rootstock and scion combination can result in higher economic returns without any additional cost. Rootstocks affect scion vigor, yield, fruit size, juice quality, and pest tolerance. However, tree growth, yield, and fruit quality interact...

Identification of genes with differential transcript abundance (GDTA) in seedless mutants may enhance understanding of seedless citrus development. Transcriptome analysis was conducted at three time points during early fruit development (Phase 1) of three seedy citrus genotypes: Fallglo (Bower citrus hybrid (Citrus reticulata×C. reticulata×C. parad...

‘Valencia’ orange (Citrus sinensis [L.] Osbeck) was grown on 17 rootstocks through seven years of age and the first four harvest seasons in a central Florida field trial severely affected by huanglongbing (HLB) disease. All trees in the trial had HLB symptoms and were shown by PCR to be infected with Candidatus Liberibacter asiaticus (Las). Large d...

Asian citrus psyllid (Diaphorina citri Kuwayama) transmits a bacterium 'Candidatus Liberibacter asiaticus' (CLas) putatively responsible for a devastating citrus disease known as Asiatic huanglongbing (HLB) (citrus greening disease). The psyllid and disease have invaded many citrus-growing regions including the United States, where the disease is s...

Candidatus Liberibacter asiaticus (Las) is a phloem-limited bacterium associ-ated with huanglongbing (HLB), one of the most destructive diseases of citrus in Florida and other citrus-producing countries. Natural transmission of Las occurs by the psyllid vector Diaphorina citri, but transmission can also occur through grafting with diseased budwood....