1. Please state project objectives and what work was done this quarter to address them:
The final data analyses were done for this paper during this quarter. This included the qPCR of CLas titer in all trees for the last two samplings of the project. Analysis of CLas titer after the six month mark did not show a decline. Yields and canopy cover also did not improve.
CLas titer was determined in two labs using two different primer sets. This was done to give us more confidence in the results. Both labs gave essentially the same results. This will be described in detail in the manuscript.
All samplings are now complete.
Our work is being completed with a draft of a manuscript that describes the results of all of our greenhouse and field work on this project. This is expected by May 2022.
2. Please state what work is anticipated for next quarter:
The paper is expected to be submitted in May 2022 to the APS Journal, Plant Health Reports
3. Please state budget status (underspend or overspend, and why):
We did not overspend on this project.
1. Please state project objectives and what work was done this quarter to address them:
During this period a manuscript describing this work is nearly completed. The current draft is attached along with this report. Our sense of this work is that this apporach still has promise. Greenhouse results were very encouraging. Foliarly applied phosphate did resude citrate levels in phloem. CLas titers did decline in graft-infected citrus saplings in the greenhouse upon foliar phosphate application. Citrus was also found to get all of its phosphate needs through foliar fertilization.
However, the field experiments were harder. We were not able to identify plots with low infection rates at the beginning of the work. The heavily infected plants may have been too weak to have the full benefits of foliar phosphate fertilization. In the first 3-6 months of the field experiments, declines in CLas titer were observed with the lowest level of foliar phosphate application but the plants did not recover in subsequent quarters.
More work on this would require larger groves with more experimentation on the frequency of foliar phosphate application. We choose application every two months and used that frequency throughout. More frequent application at lower doses may improve the efficay of foliar phosphate treatments. This treatment is also more likely to work on younger trees with less infection. Younger trees were used at the Imokalee site but those trees were highly infected. The trees in Hamilton were more than 25 years old.
I remain confident that nutritional approaches can help this problem. It will just require the correct nutrients applied at the right time. The upcoming manuscript is entitled A systems biology approach suggests a simple strategy to alleviate citrus greening disease.
Abstract of manuscript:
Citrus greening disease is now completely endemic to Florida citrus trees, having spread rapidly across all counties in the past 20 years and causing devastating economic losses. The diseases etiological agent is the unculturable bacterium, Candidatus Liberibacter asiaticus (CLas). Liberibacter crescens, the closest culturable relative, was discovered to prefer citrate as its most effective carbon and energy source. Plants load citrate in response to phosphorus deficiency. In Floridas calcareous soils, supplemental phosphate fertilization is very low due to the assumption that it is readily available for plants through the soil. It is likely that citrus trees are loading citrate to mine phosphorus from the soil, which could inadvertently exacerbate CLas infection. In greenhouse experiments, foliarly applied phosphate is easily taken up by the plants, resulting in decreased free-citrate levels in the phloem, and delaying the onset of CLas infection. Our field experiments show improvements in mature trees where CLas infection is well established, and infected psyllids maintain infection.
2. Please state what work is anticipated for next quarter:
None. This report and the attached manuscript respresent our final contributions to CRDF.
3. Please state budget status (underspend or overspend, and why):
We did not overspend on this project.
1. Please state project objectives and what work was done this quarter to address them: To determine how many leaf nutrient sampling per year are required to effectively capture the tree nutritional statusand adjust fertilizer accordingly.2. To establish the relationship of leaf nutrient concentration with yield, fruit drop, and canopy density3. To determine how the leaf nutrient (all 14 nutrient) levels change in the tree throughout the year.4. To evaluate how the leaf age affects the leaf nutrient status. In this quarter we were able to fertilize the trees for spring based on spring and summer flush nutrient analysis. In addition we have tageed newly emereged spring flush for nutrient analysis for this year. We were able to perform another set of nutriet analysis in this quarter as well. In addition we have been collecting leaf samples from fruiting an non fruting branches for comparison. The prelimnary analysis shows that spring flush are deficient in immobile nutrients as compared to random leaves therefore, suggesting that method of sampling can sway the results signifcantly. In addition we are seeing that fruting branches show low levels of consistent acculumation of micronutrients in the leaves wherease the non fruiting branch decrease in micronutrients from summer to fall thus the suggesting a higher metabolism of nutrients. 2. Please state what work is anticipated for next quarter: 1. Data analysis and interpretation2. Collecting samples for nutrient analysis3. Applying fertilizer treatments based on leaf nutrient analysis results 3. Please state budget status (underspend or overspend, and why): The budget is being spent as per the plan where major funds have been used for nutrient anlaysis.
1. Please state project objectives and what work was done this quarter to address them: The overall goal of the project is to develop fertilization strategies to best match nutrient supply and demand, and develop recommendations for optimal nutrient application timing as compared to a simple constant supply, which will improve fruit yield, quality, and reduce fruit drop. A)Objective 1) Test if a reduced N-P-K nutrient supply in the fall is safe for sustaining HLB-affected citrus, and whether it can improve fruit quality to facilitate earlier maturity / harvesting and reduce fruit drop: We established two replicated field trials with 10 fertilizer rate and timing combinations to evaluate the growth, fruit development, maturity, yields and quality of 5-year old Valencia and Hamlin trees on X-639 rootstock. The first fertilizer of about 20% annual N was applied in the first week of March. Soil samples were collected from each plot for nutrient analysis, vacuum lysimeters were installed under trees to sample nutrient leachates, and minirhizotrons were installed in the field to measure root growth. Soil P tests in the site were hight to very high, so we omitted P fertilizer from the blended fertilizer in order to deplete soil P reserves down to nominal levels. The third field trial was established on 5-year old Sugarbelle trees, and sub-objectives were modified to focus on improving fresh-fruit characteristics, particularly peel thickness, fruit size, color break, juice content, and internal quality (brix, acid). The basis for this refocusing was in response to the Sugarbelle “soft fruit” and quality reports of the 2021/22 season. Objective 2) Develop an optimized, practical fertilizer timing management profile to boost fruit quality and reduce fruit drop for HLB-affected citrus based in part on the sigmoidal nutrient demand curve defined by four physiological growth phases (0=bloom/fruit set; 1=cell division; 2=cell enlargement; 3=maturation): We are using the existing Citrus Diagnosis smartphone AI app as a baseline, and exploring improved methods for classifying foliar nutrient deficiency symptoms such as magnesium, iron, manganese and zinc so that the intensity of deficiency can be quantified from the severity and extent of chlorotic tissue on an area basis. Semantic segmentation models were trained on leaf images to quantify chlorosis and generative adversarial networks were tested to generate hypothetical synthetic nutrient symptoms to include in a comprehensive fertilizer management and nutrient modeling app. B) New developments: sub-objectives concerning the Sugarbelle trial were refocused on solving the current fruit quality issues, but temporal fertilization strategies are still at the core of the trial. C) Issues: We are concerned about the low fruit set in the city block. The trees flowered in January, and the bloom was apparently damaged by the January 30 freeze. The trees produced some recovery bloom about a month later, but it was small. 2. Please state what work is anticipated for next quarter: The second of four fertilizer applications will be made in the first week of April, and the third will be in mid May. Some treatments in the 10-treatment structure will not receive fertilizer at every date, or receive variable amounts of fertilizer in order to construct 10 different fertilization strategies (supply curves) over time. Soil, lysimeter and leaf sampling, processing and analysis will be ongoing, as will tree size and fruit measurement. The first Aerobotics drone survey will fly in early May, to evaluate tree health and size indicators. 3. Please state budget status (underspend or overspend, and why): Grove chargebacks for 3 acres of field experiments were initiated, partial salaries of 3 personnel were allocated for the new efforts of this project, and supplies for installing minirhizotrons were purchased. There may be a temporary underspend due to system lag in reporting the modified salary allocations to this project, which was done recently.
1. Please state project objectives and what work was done this quarter to address them: Objective 1: Determine effects of lowered soil pH on CLas populations and root physiology including internal root apoplast and vascular tissue pH. Due to a collapse in our inoculum trees, we are psyllid inoculating trees for these experiments and will start the greenhouse portion of the study in Spring 2022. All CLas inoculated and non-CLas inoculated trees are ready for the experiment slated for April 29, 2022. Objective 2: Field test multiple acidification materials including organic acids for tree response CLas suppression, nutrient uptake, and root and vascular pH changes In this quarter, we collected soil and leaf tissue samples which show sufficiency in all treatments. We are now evaluating root density, PCR and of selected trees. 2. Please state what work is anticipated for next quarter: Fruit harvest and fruit quality evaluation will also be accomplished this quarter on April 19 and April 21, 2022. Injection of acids and S application were delayed until harvest to avoid any impacts on fruit drop. 3. Please state budget status (underspend or overspend, and why): The budget is on track and meeting the project milestones.
During October 2021-Janury 2022 we surveyed sting nematode populations in several Polk and Highlands County orchards before focusing on 12 quadrats (all moderately-highly infested) across 30 acres of a declining grove near Babson Park destined for replanting in spring 2022. The nine-year-old trees in the grove were clipped to preserve the current irrigation system; however, the grower uprooted 20 trees throughout the grove, revealing uniformly severe root damage on all trees immediately below 30 cm depth. There were relatively fewer symptoms on the surface layer of fibrous roots supporting the need for deep soil sampling to accurately assess sting nematode abundance in citrus. The extensive and comprehensive damage to root systems by sting nematode suggested that the grove would be suitable for the trial.Three hundred trees (Valquarius on 812) were planted on 3/22/2022 and half the trees were covered immediately with individual protective covers (IPC). The design of the experiment is a completely randomized block with 15 blocks, each with 4 factorial treatments (all combinations of IPCs and nematicide application), each applied to 4-tree plots. Plots are separated by single buffer trees. Thus, we will evaluate the effect of sting nematodes on trees exposed to or protected from Asian citrus psyllids that are treated or not treated for nematode control. We dissassembled the fittings and poly-tubing used to deliver nematicides to 32, 4-tree plots in a previous experiment and reconfigured and installed the equipment in these 15 blocks. The first nematicide treatment will occur in April 2022 and will occur in each autumn and spring thereafter. In November 2020 we collected sting nematode-infested soil from a citrus orchard and extracted and handpicked 30-50 mixed-stage individuals per 8 pots each of St. Augustine grass and sorghum sudangrass to establish cultures to serve as inoculum for trials to evaluate tolerance of rootstocks to sting nematode. Within two months, sampled pots contained as many as 40 nematodes per cm3 of soil. In December 2022 we autoclaved Candler sandy soil and filled 4, 150 gallon tanks in a greenhouse. St. Augustine grass stolons and soil from the nematode cultures were transplanted into two of the tanks in January. the other two tanks were planted with non-infested St. Augustine. Construction on the greenhouse that began in early January was still ongoing in April, precluding further research until completed.
Objective 1. To illustrate whether application of bactericides via trunk injection could efficiently manage citrus HLB and how bactericides via trunk injection affects Las and HLB diseased trees. 1.1. Determination of the in planta minimum bactericidal concentrations (MBCs) of bactericides against LasThis has been completed for both streptomycin and oxytetracycline against Las. A manuscript entitled: “Residue dynamics of streptomycin in citrus delivered by foliar spray and trunk injection and effect on Candidatus Liberibacter asiaticus titer” was accepted for publication by Phytopathology.1.2. Effect of bactericides via trunk injection on citrus HLB disease progression, tree health, yield and fruit quality in different aged trees with a different disease severityThe field experiments were performed at four different groves on different aged trees with a different disease severity. They are one located in Avon Park, FL, 3-year old Valencia trees; one in Bartow, FL, 2-year old W. Murrcot trees; and one in Auburndale, FL, 7-year old Hamlin trees (planted in 02/2012). The last one is in CREC-, Lake Alfred, FL, 20-year old Hamlin trees. The HLB disease severity and tree size (canopy volume and trunk diameter) in the four groves were estimated immediately prior to treatment application. For the field tests, the experiment design is a randomized complete block design (RCBD) for 9 treatments, including 6 injection treatments (3 different doses for OTC or STR), 2 spray treatments (OTC or STR spraying), and one No treatment as a negative control. Each injection treatment consisted of 9 or 15 trees divided into 3 blocks of 3 or 5 trees each. Each spray treatment consisted of 30 trees divided into 3 blocks of 10 trees each. For all the four field trials, the injection treatment applications were completed by the end of April 2019. The 1st application of spray treatments were completed during spring flushing in February or March 2019, the 2nd applications were conducted in late June to early July 2019, and the 3rd applications were conducted in early to middle October 2019. Leaf samples have been collected from the treated trees at the following time points: 0 (pre- injection), 7, 14, 28 days, 2, 4, 6, 8, 10 and 12 months after treatment (MPT). The estimation of Las titers in these leaf samples are ongoing with qPCR assays. The first estimation of HLB disease severity and growth performance (height, trunk diameter, and canopy volume) of immature trees after treatment were performed in May 2019 (three months after the injection) and continued in a 3-months interval. Fruit yield and quality data were collected for the Bartow trial (W. Murrcot), Auburndale trial (Hamlin), and CREC trial (Hamlin) in January 2021. We investigated the effect of 10 adjuvants on oxytetracycline absorption via foliar spray. Four adjuvants including Flame slightly increased the antimicrobial effect of OTC on Las.We have collected data for yield and quality. Objective 2. To examine the dynamics and residues of bactericide injected into citrus and systemic movement within the vascular system of trees and characterize the degradation metabolites of bactericides in citrus. Leaf and root samples have been collected from OTC or STR treated trees in the Avon Park grove at the following time points:0 (pre- injection), 2, 4, 7, 14, 28 days, 2, 4, 6, 8, 10, and 12 months after injection. The samples have been processed for OTC or STR extraction, and the concentrations of OTC and STR in these samples were determined by HPLC assays. Fruit samples were collected for the Bartow trial (W. Murrcot), Auburndale trial (Hamlin), and CREC trial (Hamlin) during harvest in January 2020, and for the Avon Park trial (Valencia) in April 2020. The samples were processed for OTC or STR extraction, and the concentrations of OTC and STR in these samples were determined by HPLC assays. We have collected data for 60 and 360 days post treatment. We have analyzed the residues of OTC and STR for fruit samples harvested in January 2022. Objective 3. To determine whether trunk injection of bactericides could decrease Las acquisition by Asian citrus psyllids (ACP)Twenty 1.5-year old citrus (Valencia sweet orange) plants were graft-inoculated by Las carrying buds in February 2020. These plants are being tested for Las infection and 4 plants were confirmed with Las infection (Ct values are between 34.0 and 35.0) at 4 months after grafting. They will be subjected to OTC or STR treatment by trunk injection and ACP acquisition access for 7 to 14 days. We have determined the time points to test OTC and STR treatment on ACP acquisition of Las. We have conducted the test regarding how trunk injection of OTC affect ACP acquisition of Las. OTC signficantly reduces ACP acquisition of Las. Objective 4. To monitor resistance development in Las against bactericides and evaluate potential side effects of trunk injection of bactericides Monitoring resistance development in Las against bactericides. Leaf samples for this test have been collected from 5 trees injected with OTC and 5 trees injected with STR at the highest doses in each of the three groves at 6 and 9 months after the injection, respectively. PCR-sequencing analysis on Las 16SrRNA gene showed there was no mutation compared with the reported sequence. We are further confirming the results. Evaluation of potential side effects of trunk injection of bactericides have been completed. We have collected another set of samples to monitor Las resistance against OTC and STR. PCR-sequencing analysis on Las 16SrRNA gene showed there was no mutation compared to the reported sequence, indicating no major changes in bacterial resistance against antimicrobials. Leaf samples were collected from OTC or STR injected trees in the Avon Park grove at two and four months after treatment for the analysis of the degradation metabolites of the bactericides. The extraction of the degradation metabolites were completed and will be subjected to HPLC assays. We are in the process of analyzing data related to how adjuvants affect bactericide delivery via foliar spray, bactericide residues in plants, and effect of bactericides on HLB positive citrus tress of different ages. We also investigated how trunk injection of OTC and STR affects phloem tissues. We are analyzing data for final report.
Conclusions of the one year preliminary study: `Parson Brown’ trees, irrespective of location, clone or rootstock had enhanced SAR activity as indicated by enhanced PR1 and PR2 gene expression. Statistically significant differences were always observed in the different locations during the March and December samplings. PP2 gene downregulation indirectly suggests an active protection mechanism in the phloem of the `Parson Brown’. Targeted RNA seq and metabolomics of the phloem would confirm these results and provide more insights into the exact mechanism of HLB tolerance. All trees (`Parson Brown’ and `Hamlin’) evaluated in this study were HLB positive with similar CaLas titer. `Parson Brown’ trees however, maintained a good canopy and held on to fruit much better than comparable `Hamlin’ trees. Oil content % ranged from 0.007 to 0.0011 in `Hamlin’ juice whereas, it ranged from 0.020 to 0.042 in `Parson Brown’ juice, depending on the location the fruit was harvested from. This could be due to clonal differences between trees grown in different locations. Lbs. Solids Per Box were comparable between `Parson Brown’ and `Hamlin.’ However, `Hamlin’ has recorded good Lbs. Solids Per Box in 2021, and samples will need be evaluated for multiple seasons to understand differences between the two early season sweet oranges. Limonin levels were less than 5 ppm in both `Parson Brown’ and `Hamlin’ and within acceptable levels. It was not possible to identify specific clones based on the data generated. Whole genome sequencing can shed insights into clonal differences by looking at the overall pattern of SNPs and INDELS among the specific selections. `Parson Brown’ trees at the Premier Citrus location in Lorida had the best growth, canopy coverage, followed by trees at the groves managed by Pat and Marty McKenna and the Premier Citrus location in Ft. Pierce. There were no significant differences in the oil content from fruit from these locations. It may be worthwhile to reintroduce a couple of these superior lines into the DPI’s parent tree program for the benefit of the citrus stakeholders.
Conclusions of the one year preliminary study: · Trees were evaluated on a quarterly basis from 8 different locations. Tree aged ranged from 20 to 40 years in these locations. Most locations had changed management several times in these years and there was no clonal identification records.· `Parson Brown’ trees, irrespective of location, clone or rootstock had enhanced SAR activity as indicated by enhanced PR1 and PR2 gene expression. Statistically significant differences were always observed in the different locations during the March and December samplings. · PP2 gene downregulation was observed only in the `Parson Brown’ trees. This indirectly suggests an active protection mechanism in the phloem of the `Parson Brown’. Targeted RNA seq and metabolomics of the phloem would confirm these results and provide more insights into the exact mechanism of HLB tolerance. · All trees (`Parson Brown’ and `Hamlin’) evaluated in this study were HLB positive with similar CaLas titer. `Parson Brown’ trees however, maintained a good canopy and held on to fruit much better than comparable `Hamlin’ trees. · Oil content % ranged from 0.007 to 0.0011 in `Hamlin’ juice whereas, it ranged from 0.020 to 0.042 in `Parson Brown’ juice, depending on the location the fruit was harvested from. This could be due to clonal differences between trees grown in different locations and could help to differentiate between the different clones. · Lbs. Solids Per Box were comparable between `Parson Brown’ and `Hamlin.’ However, `Hamlin’ has recorded good Lbs. Solids Per Box in 2021, and samples will need be evaluated for multiple seasons to understand differences between the two early season sweet oranges. · Limonin levels were less than 5 ppm in both `Parson Brown’ and `Hamlin’ and within acceptable levels.· It was not possible to identify specific clones based on the data generated. Whole genome sequencing can shed insights into clonal differences by looking at the overall pattern of SNPs and INDELS among the specific selections. · `Parson Brown’ trees at a grower location in Lorida had the best growth, canopy coverage, followed by trees in Lake Wales, Sebring and Ft. Pierce. There were no significant differences in the oil content from fruit from these locations. It may be worthwhile to reintroduce a couple of these superior lines into the DPI’s parent tree program for the benefit of the citrus stakeholders.
Our project is examining phloem gene expression changes in response to CLas infection in HLB-susceptible sweet orange and HLB-resistant Poncirus and Carrizo (a sweet orange – Poncirus cross). We are using a recently developed methodology for woody crops that allows gene expression profiling of phloem tissues. The method leverages a translating ribosome affinity purification strategy (called TRAP) to isolate and characterize translating mRNAs from phloem specific tissues. Our approach is unlike other gene expression profiling methods in that it only samples gene transcripts that are actively being transcribed into proteins and is thus a better representation of active cellular processes than total cellular mRNA. Sweet orange, and HLB-resistant Poncirus and Carrizo (sweet orange x Poncirus) will be transformed to express the tagged ribosomal proteins under the control of characterized phloem-specific promoters; tagged ribosomal proteins under control of the nearly ubiquitous CaMV 35S promoter will be used as a control. Transgenic plants will be exposed to CLas+ or CLas- ACP and leaves sampled 30, 60, 90, and 120 days later. Ribosome-associated mRNA will be sequenced and analyzed to identify differentially regulated genes at each time point and between each citrus cultivar. Comparisons of susceptible and resistant phloem cell responses to CLas will identify those genes that are differentially regulated during these host responses. Identified genes will represent unique phloem specific targets for CRISPR knockout or overexpression, permitting the generation of HLB-resistant variants of major citrus cultivars.During the 1st quarter of our 1st 6 month no cost extension (the original end date was 11/30/2021; the current end date is 05/31/2022), the Stover lab has finally identified several high expressing lines of the p396 phloem-specific promoter in Poncirus. These will be shipped to the Rogers lab shortly, as soon as their BRS transgenic movement permit is renewed. APHIS has changed the on-line interface for applying for BRS movement permits and renewals are much delayed. At least 4 high expressing lines for each of the other 8 promoter/genotype combinations are in the containment greenhouse facility at Ft. Detrick and are being prepared for no-choice psyllid inoculation experiments.The Rogers lab has continued no-choice psyllid inoculation experiments on the many lines they have received from the Stover lab and continued ribosome pull-downs from the tissue collected. ARS facilities are still at a maximum of 25% occupancy due to the COVID-19 pandemic; we are teleworking the remaining time. This 25% occupancy cap will be lifted on Monday, March 28th, as long as the CDC community COVID metrics are in the ‘low’ category (which they are currently for Frederick County, MD). This will allow more rapid progress on grant milestones. Additionally, we are hopeful that the relaxed restrictions on in-person work will make our facility a more attractive place to work for potential post-doc candidates. Hiring a post-doc to help on the project will also allow more rapid progress on grant milestones.
1. Please state project objectives and what work was done this quarter to address them: Objective. To determine the influence of compost during the first three years of tree establishment on growth, productivity, and root and soil health of citrus trees on rootstocks with different vigor-inducing capacity. The second of the biannual compost applications for year 2 was conducted in November. Monthly leaf flush ratings and soil moisture measurements were conducted; we continue seeing the same trends for higher soil moisture content in the compost plots compared with non-compost plots. Fibrous root samples were collected for physiological (root respiration) and structural analyses. Preliminary analysis of soil microbial data indicates some differences in the rhizosphere bacterial composition between rootstocks. In addition, early analysis points to possible differences in the response of the soil microbial community to compost application based on the rootstock. 2. Please state what work is anticipated for next quarter:Flush ratings and soil moisture determination will continue.Fruit yield and fruit quality will be determined.Data analyses will continue.Soil microbial sequence data analysis will continue. 3. Please state budget status (underspend or overspend, and why): Approximately 61% of funds have been spent, which is mostly in accordance with the timeline.
This project was initially awarded to Dr. Ferrarezi. Following Dr. Ferrarezi departure from UF/IFAS the project was transferred to Dr. Rossi. Finally, the project was early terminated in December 2021. The purpose of this project was to assess nitrogen (N) fertilization rates for high-density plantings of different scion and rootstock combinations in four commercial citrus growers. The overall approach was to 1) determine the appropriate N rates needed to support tree growth and productivity, 2) compare data obtained with existing UF/IFAS N recommendations, and 3) revise best management practices (BMPs) for N application in young trees planted in high-density plantings affected by Huanglongbing (HLB). The Ph.D. student and Research Assistant dedicated to the project were hired in Spring 2021. Grower collaborators participating in the project were contacted in Spring 2021. The 4 growers comprised: 1) IMG Citrus (Mr. Brian Randolph), 2) Peace River Citrus (Mr. Larry Black Jr.), 3) Agromillora Florida/ Lost Lake Groves (Mr. Clay Pedersen), 4) Graves Brothers (Mr. David Howard). The graduate student and the research assistant scheduled and performed site visits to all locations in Spring 2021 and Summer 2021. The planting densities and variety/scion combinations were chosen, field maps generated, experimental units identified with permanent signs, and the current information regarding N fertilization were requested to growers in Spring 2021. Dr. Ferrarezi contacted Yara (Bill Easterwood) and received fertilizer donations for the first year (20 tons or 40k lbs). Unfortunately, the delivery was delayed due to COVID-19 logistics finding a local distributor, blending the four different formulations, and delivering in Fort Pierce. We were able to receive both calcium nitrate and ammonium nitrate despite the challenges of finding this fertilizer. That was only possible because of the partnership with Yara. Treatments were applied all locations in Summer 2021 and initial tree size and leaf area index data collection was performed as expected in Summer 2021. The project was early terminated by the CRDF Board at the end of the first year and money were returned to CRDF in January 2022.
1. Please state project objectives and what work was done this quarter to address them:
Objective 1: Determine effects of lowered soil pH on CLas populations and root physiology including internal root apoplast and vascular tissue pH.
Due to a collapse in our inoculum trees, we are psyllid inoculating trees for these experiments and will start the greenhouse portion of the study in Spring 2022.
Objective 2: Field test multiple acidification materials including organic acids for tree response CLas suppression, nutrient uptake, and root and vascular pH changes
We have marked out plots for our experiments at two sites on 15-year old and 14-year-old trees. we collected soil and leaf tissue samples for preliminary analysis. We have also applied elemental sulfur, sulfuric acid, fulvic acid and humic acid in August and September 2021. We determined canopy and trunk size and PCR measurements to establish baseline. We will determine root density responses and root PCR every 6 months.
We have also recruited two postdoctoral associates to help with data collection and documentation of the results.
2. Please state what work is anticipated for next quarter:
In the next quarter we will wait for psyllid or bud inoculated trees to develop initial symptoms before testing for CLas for objective 1. We will apply more acidifying products in January 2022.
3. Please state budget status (underspend or overspend, and why):
Now the budget spending is on track.
1. Please state project objectives and what work was done this quarter to address them: To determine how many leaf nutrient sampling per year are required to effectively capture the tree nutritional statusand adjust fertilizer accordingly.2. To establish the relationship of leaf nutrient concentration with yield, fruit drop, and canopy density3. To determine how the leaf nutrient (all 14 nutrient) levels change in the tree throughout the year.4. To evaluate how the leaf age affects the leaf nutrient status.TThe project was initiated in January 2021. In this quarter we were able to tag summer flush on mild and severely HLB-symptomatic trees as well as sample the spring flush for leaf nutrient analysis. We also collected the data on leaf size, weight, chlorophyll index, and starch along with nutrient profile. The preliminary findings were presented at annual meeting of ASHS, Denver, Colardo. 2. Please state what work is anticipated for next quarter: 1. Data analysis and interpretation2. Processing samples for starch3. Collecting samples for nutrient analysis4. Applying fertilizer treatments based on leaf results 3. Please state budget status (underspend or overspend, and why): Currently, the project is in early phase.The budget is being spent as per the plan where major funds have been used for nutrient anlaysis. We have found dedicated personnels to work on this project starting this quarter.
1. Please state project objectives and what work was done this quarter to address them: To determine how many leaf nutrient sampling per year are required to effectively capture the tree nutritional statusand adjust fertilizer accordingly.2. To establish the relationship of leaf nutrient concentration with yield, fruit drop, and canopy density3. To determine how the leaf nutrient (all 14 nutrient) levels change in the tree throughout the year.4. To evaluate how the leaf age affects the leaf nutrient status. The project was initiated in January 2021. In this quarter we were able to fertilize the trees based on spring flusg nutrient analysis. In addition we have been able to sample spring flush for the second time and are able to make comparisons between randomly picked mature leaves versus spring tagged mature leaf for nutrient analysis. The prelimnary analysis shows that spring flush are deficient in immobile nutrients as compared to random leaves therefore, suggesting that method of sampling can sway the results signifcantly. In this quarter we also sampled summer flusgh for the leaf nutrient analysis for the first time. 2. Please state what work is anticipated for next quarter: 1. Data analysis and interpretation2. Collecting samples for nutrient analysis3. Applying fertilizer treatments based on leaf nutrient analysis results 3. Please state budget status (underspend or overspend, and why): The budget is being spent as per the plan where major funds have been used for nutrient anlaysis.
(863) 956-8817
(863) 956-5894
700 Experiment Station Road
Lake Alfred, FL 33850
Email Us
