1. Please state project objectives and what work was done this quarter to address them: Specific objectives are:1) To determine the right timing for Zn and K treatments to minimize fruit drop.2) To determine effects of GA3 and 2,4D applications on fruit retention when applied at different times during fruit development.3) To develop a strong and proactive outreach program. For objective 1 we did a new set of treatments by the end of September in Hamlin as we did last year. This date of treatment was the one that got best results last season in terms of yield, despite the effects of hurricane Ian. As before, every set of treatments is performed in an independent replicated block, so treatments are applied only once, to assess the best timing to achieve the best results. Trees under Zn and Zn+K treatments continue having greener canopies. This is consistent with effects we saw last year. Also, we are performing canopy analysis by using the ImageJ program. In Hamlin, trees treated with Zn continue to have significantly more dense canopies and more canopy volume than controls. These measurements have been done also for objective 2, and we are analyzing data. For objectives 1 and 2 we are also analizyng foliar nutrient concentrations.We see less oxidative stress levels in trees treated with Zn and Zn+K.Fruit drop is being now monitoired weekly. We still don’t see differences in treatments but this is usually seen in October-November. Objective 3:-Optimizing foliar sprays of zinc and potassium to prevent fruit drop, by Fernando Alferez, Daniel Boakye, Murillo De Sousa and Pablo Orozco. Citrus Industry, Tip of the Week, October 2023. 2. Please state what work is anticipated for next quarter: Treatments for objectives 1 and 2 will continue as programmed in Hamlin. We will continue fruit drop assesments weekly. Sampling will continue as well and we will finisnh data analysis of samples analyzed in the last quarter for objectives 1 and 2. Harvesting of Hamlin will be done in December-January. Treatments in Valencia will start. 3. Please state budget status (underspend or overspend, and why): Budget is on track
1. Please state project objectives and what work was done this quarter to address them: The objectives of this project are: 1, To study the effect of Brs on priming immunity on young, newly planted trees. This will allow to know for how long immune response will last after Br application, so we can adjust timing (number of applications). We have continued treatments and samplings. After 8 months (with a monthly application), most of the trees (around 60%) are still HLB-negative. Denser foliage has consolidated in a denser canopy. Fall flush was highly syncronized, following the trend we observed during Summer flush. 90% of the trees treated with Brs achjieved fully expanded leaf status at the same time. This happened only in 20% of non-treated trees. This indicates that flushing occurred at the same time in Br-treated trees, and will allow better planification of insecticide sprays. 2, To determine the best time of application (frequency) to achieve maximum protection against pests and disease in newly planted trees. Immunity is still greatly increased after 45d of treatment. We have now started plots applying Brs every 45d or 60d. We will monitor the same parameters, icluding Ct values and tree health. 3, To determine the effect of Br application on advancing fruit maturation in both Valencia and Hamlin. Treatments started in September on Hamlin. We performed two different sets of treatments: biweekly treatment and only once treatment. We are following quality every 15 days, including internal quality and external color development. So far, it is remarkable that internal maturation and quality are in general superior than last year. At the beginning of the treatments, control fruit was already at 9.38 Brix. This value was about 8.2 last season. So far we do not see a significant increase in Brix with Br treatment. This is coincident with what we saw last year, as differences started to be significant in November.Values for early November are 9 for control and 9.43 for Br-treated. However, ratio is greatly increased, 13.32 in Br-treated as compared to 11.5 in controls. External color is also increased. 2. Please state what work is anticipated for next quarter:For objectives 1 and 2 we are continuing sampling and molecular analysis.In objective 3, treatments in mature Hamlin trees are already running. We will be harvesting fruit in December-January, depending on the commercial farm schedule. Last season, harvesting was performed by January 5th. We will determine yield and fruit quality. We will start treatnments in Valencia in early January.For objectives 1 and 2 we will continue treatments, samplings and molecular analysis to determine the best timing for treatments to achieve the most protection against psyllid infestation. For objective 3, we will start in August treatments on Hamlin. We will also continue analyzing juice samples from Hamlin and start analysis on juice samples from Valencia. We have included also an injection treatment of Brs in trees, This was not in the proposal, but we believe it may have interest. We have started in October. We will be injecting once per month until harvest and measuring the same parameters as in objectives 1, 2 and 3. 3. Please state budget status (underspend or overspend, and why): Spending is on track
1. Please state project objectives and what work was done this quarter to address them: Objective 1: To compare different rates and annual use patterns of trunk-injected OTC on late-season (Valencia) and early-season (Hamlin) sweet orange tree and their effects on health, yield, and fruit quality over a period of 3 years in a commercial citrus production environment.Obective 2: To compare spring with late summer injections in Valencia orange trees to determine if OTC effects on yield can be enhanced, and the harvest window extended, through timing of injections. Trees were monitored. No phytotocicity was obserevd after the spring injections. Fall injections were conducted in September in the Valencia trial. No phytotoxicity was noted. 2. Please state what work is anticipated for next quarter: We will conduct tree measurements. Leaves will be collected for CLas assessment. In the Hamlin trial fruit will be collected for fruit quality assessment, and trees will be harvested. Tentative harvest time is middle of December. 3. Please state budget status (underspend or overspend, and why):The budget is as expected.
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:Routine measurements of tree health and performance continued, including leaf nutrient analyses, chlorophyll index, canopy and trunk size, fruit growth rates and incidental fruit drop (not pre-harvest). The study comprehensively analyzed the nutrient dynamics of leaves, revealing notable variations in nitrogen (N) concentrations. During the cell-division stage / physiological fruit drop in May to the cell-enlargement stage starting June, both Hamlin and Valencia varieties exhibited higher leaf N concentrations in most fertilization treatments, except for two linear supply treatments (T1 and T2). This increase in leaf nitrogen could contribute to enhanced crop health and performance. In contrast, potassium (K) concentrations in leaves remained consistent across various fertilization treatments throughout the growing period. However, a spike in leaf K concentration was observed in both Hamlin and Valencia during the fruit maturation phase (September-), particularly in treatments with linear nutrient supply and late fertilization. This is significant given that numerous studies indicate that lower potassium levels are preferable for improved fruit quality and peel coloration. Conversely, the temporal fluctuations of other nutrients did not show significant variations across different fertilization treatments.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):In the 2023 growing season, an increase in fruit drop was observed in both Hamlin and Valencia varieties as the season progressed. Specifically, the lowest cumulative fruit drop per tree in Hamlin was recorded under treatment 3 (100% sigmoidal fertilizer supply). On the other hand, Valencia showed a higher cumulative fruit drop per tree, particularly in the linear supply with late fertilization treatment (T2). The overall percentage of fruit drop will be determined after the harvest.Regarding fruit growth, no significant differences were observed in the relative fruit growth rate among the various fertilization treatments. B) New developments: NoneC) Issues: None2. Please state what work is anticipated for next quarter:Routine lysimeter sampling, leaf sampling, processing and analysis will be ongoing, as will tree size, root growth and fruit drop and growth measurement.Plan for October to December:1. Sampling for leaf nutrient analysis2. Fruit diameter measurement3. Collection of leachates for nitrate N loss and analysis4. Scanning of the Minirhizotron for root growth5. Fruit drop count in every two weeks till harvesting in Hamlin and Valencia6. Harvesting Hamlin variety for yield and fruit quality measurement7. Soil sample collection from Hamlin variety blockIn the Sugar Belle peel thickness experiment, all treatment allocation was completed for this year’s experiment and final harvesting will be done during December for fruit quality and peel thickness measurements. Leaf sample collection will be done after harvesting of fruits and processed for leaf nutrient concentration. 3. Please state budget status (underspend or overspend, and why):Spending rate is approximately on track.
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.
We got our experiment in rhizotrons completed in September 2023. Sample processing and data analysis is under way.
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 continued root sampling and soil pH determinations. We request 6-month extension because will need to collect fruit yield and juice quality data in March/April 2024.
2. Please state what work is anticipated for next quarter:
A poster on Objective 1 will be presented at the Soil Science Society of America annual meeting in St. Louis, MO.
3. Please state budget status (underspend or overspend, and why):
The budget is on track and meeting the project milestones. However, we plan to request a no-cost extension so as to collect a fourth harvest in 2024 and also owing to some delays we had in executing the greenhouse portion of the project due to changes in project leadership.
1. Please state project objectives and what work was done this quarter to address them: Objectives: 1) Test the efficacy of different injection devices, 2) Determine the most effective formulation of OTC, 3) Determine the best month of injection and most appropriate OTC concentration based on tree size. Trial 1: SW FL(Duda) – 8-year-old Valencia/Carrizo. Trial 2: SW FL (Graves Bros) – 8-year-old Valencia/Kuharske. Trial 3: East coast (Graves Bros) – 9-year-old Valencia/sour orange. Trial 4: East coast (Graves Bros) – 4-year-old Valencia/x639. Trial 5: Central ridge (King Ranch) – 4 year-old OLL8/x630 Leaf CLas detection analyses are in progress. Leaves were collected for nutrient analysis (in progress). Trunk injury/wounding was assessed in each trial. August and September injections were conducted in trials 4 and 5. September injections were conducted in trial 1. Selected information from these trials was presented at several industry events and conferences, including the Citrus Expo, Packinghouse Day, ASHS, and the International Citrus and Beverage Conference. Research findings were also disseminated in Citrus Industry magazine and through the UF/IFAS citrus podcast. 2. Please state what work is anticipated for next quarter:We will conduct tree size measurements. CLas titer analysis will continue. Fruit drop and tree health will be monitored. 3. Please state budget status (underspend or overspend, and why):The budget is on track although it may appear to be underspent as a large portion of funds are intended to be used for fruit OTC analysis at the USDA National Science Lab in Gastonia, NC, and for fruit quality analysis in 2024.
1. Please state project objectives and what work was done this quarter to address them: Main objective: To determine the large-scale efficacy of trunk injection of OTC on citrus tree health, fruit quality, and yield in existing rootstock trials in three different commercial growing environments. Sub-objectives: a) test the efficacy of OTC injection in the rootstock trunk compared to injection into the scion, and b) determine whether OTC injection increases/restores root densities and if there are interactions with the rootstock. In all three trials: Trunk diameters were measured. Leaves were collected for CLas and OTC detection; laboratory analysis is ongoing. Leaves were collected for nutrient analysis; analysis is in progress. Roots were collected to assess root density. So far we did not detect any significant differences between OTC-injected and non-injected trees for the root densities but we found differences among rootstocks.Selected information from these trials was presented at the Citrus Expo and in Citus Industry magazine. 2. Please state what work is anticipated for next quarter: We will continue with leaf collections for CLas and OTC analysis. Tree health will be monitored. Trunk/wound damage will be assessed. CLas and OTC analysis will continue. 3. Please state budget status (underspend or overspend, and why):The budget is as expected.
On January 5, 2023 18 plants each of LB8-9xS13-15-16 and UFR-5 were potted in 10x10x30 cm containers with autoclaved Astatula sand:ProMix (3:1). Half of the pots of each rootstock were inoculated with 210 sting nematodes in 10 ml water and the remaining half with 10 ml of nematode suspension filtrate from which nematodes were removed by passing repeatedly through a 25µ seive. The plants were maintained in a greenhouse until July 5 when they were removed from pots, separated into tops, tap-pioneer roots, fibrous roots, dried (70o) and weighed. Sting nematodes in 250 cm3 soil from each pot were recovered by sucrose centrifugation. The trial was designed to compare the resistance (nematode reproduction) and tolerance (of nematode damage) between two UF rootstocks that performed best and worst in the mass-screening-tolerance assays reported previously. It is not possible to attribute nematode reproduction to any rootstock in the latter assay, because all lines are grown together in the same large tank. The top weights of UFR-5, and LB8-9xS13-15-16 plants were reduced by 18% and 36% (P=0.05), respectively, in the pots with nematodes compared to the non-nematode pots. Fibrous root density was reduced by nematodes by 10% and 48% (NS due to high variability in the damage) in the respective rootstocks. Two of the LB8-9xS13-15-16 plants died during the trial. The average nematode density in pots with UFR-5 was 535 (all stages) and in pots with LB8-9xS13-15-16 was 378. The trial demonstrated that while UFR-5 exhibited greater tolerance to sting nematodes compared to LB8-9xS13-15-16 in the tank-tolerance assay, the line is not resistant to nematode reproduction. UFR-5 also showed somewhat greater tolerance to the nematode in the pot study than did LB8-9xS13-15-16; however, more pronounced damage in pots compared to that in the tank (Figure 1 in accompanying MS Word document) suggests that the relative rootstock tolerance under more stringent conditions such as the field, where the nematode is not presented with a choice of rootstocks (as in the tank study), remains unresolved. Additional resistance trials with these and additional rootstocks are scheduled to run in tandem with the ongoing and remaining tolerance studies.
The third oxamyl application of the trial occurred on March 24 and soil samples were taken on 1 May. As reported previously, the sting nematode populations remained low in this grove (<10 nematodes/250 cm3 soil), and it was not possible to distinguish significant treatment differences, although average population density during the past year was 47% lower in plots treated with oxamyl in the uncovered trees and 23% lower in the plots with IPCs. Fibrous root density in May was unaffected by nematide application in either covered or uncovered trees. It is noteworthy that prior to the trial, in January 2022, when the orchard was replanted, 20 trees throughout the block were pulled to examine the root systems (Fig. 1 in the attached word document). Every tree had an extensive surface root system with varying amounts of fibrous roots; however no tree had roots deeper than approximately 12 inches and every tree exhibited extensive sting nematode damage at about the 12 inch depth. In other words, sting nematode damage was severely limiting the depth of the root systems. Moreover, the measured sting population density throughout the block was an order of magnitude larger at that time than since the block was replanted and this trial began. Rootstock may be affecting sting nematode density in the trial. The rootstock US 812 was introduced in the grove when it was replanted in 2022. A CRAFT roostock trial in an adjacent grove includes a number of USDA and UF rootstocks, and sting nematode populations measured in that trial several years ago showed US 812 to have the lowest number of nematodes of the rootstocks in the trial. US 812 was also among the top two performing rootstocks in the ongoing greenhouse tolerance trials and will be evaluated a second time in combination with UF and other USDA rootstocks a trial that will terminate in October 2023. In an ancillary project, initiated in this grove at the same time as the current IPC-nematicide trial, we are evaluating an unregistered nematicide produced by Syngenta. The trial is being conducted in the same manner as the IPC-nematicide trial (spring and autumn applications followed by summer and winter assessments), but without any protection from HLB. The Syngenta material was the best-performing of four new nematicides tested in a previous CRDF trial to control sting nematode. The new chemistries are much safer to use than traditional nematicides, have high toxicity to nematodes but very low toxicity to mamals birds and fish. Moreover, the recent availablity of several new nematicides will allow rotation of chemistries with different modes of action to help prevent loss of efficacy due to nematode resistance development or the development of accelerated microbial degradation. The new product is being tested at low and high rates (L and H), with and without an adjuvent (S), and with applicatons either once a year in spring (S) or twice annually in spring and fall (F). To date the new nematicide has performed consistently as well as or better than oxamyl against sting nematode (Fig. 2 in the attached Word document), albeit under conditions of relatively low population density in this grove. All treatments have measured efficacy ranging from 57% to 90% against the nematode. On May 14 the following rootstocks were planted into the tanks infested or not with sting nematode and will be harvested in 20 weeks to comprise the third tolerance trial: UFR 1, UFR 5, Orange 16, MG 11, CB8-9xS13-15-16, S10x639-12-32, US 812, US 942, US 802, US 1284, US 1283, US 1516, Swingle, Kuharske, Sour orange, Sweet orange.
1. Please state project objectives and what work was done this quarter to address them: Specific objectives are:1) To determine the right timing for Zn and K treatments to minimize fruit drop.2) To determine effects of GA3 and 2,4D applications on fruit retention when applied at different times during fruit development.3) To develop a strong and proactive outreach program. In Objective 1 we have performed the applications of Zn and K and their combination in early June and in July, as we did last year. Also, we have performed canopy analysis by using the ImageJ program after the first year of tretments. In Hamlin, trees treated with Zn had significantly more dense canopies and more canopy volume than controls. This effect was less evident with K and in the combined treatment. In Valencia trees all treatments increased canopy volume and density significantly. These measurements have been done also for objective 2, and we are analyzing data.We have started to analyze samples to determine oxidative stress levels. In objective 3, 7 presentations from Dr Vashisth’s lab and 4 from Dr Alferez’s were delivered at the ASHS annual meeting in Orlando, July, 2023. 2. Please state what work is anticipated for next quarter: Treatments for objectives 1 and 2 will continue. We are starting now fruit drop assesments weekly. Sampling will continue as well and we will finisnh data analysis of samples analyzed in the last quarter for objectives 1 and 2. 3. Please state budget status (underspend or overspend, and why): Budget is on track
1. Please state project objectives and what work was done this quarter to address them: The objectives of this project are: 1, To study the effect of Brs on priming immunity on young, newly planted trees. This will allow to know for how long immune response will last after Br application, so we can adjust timing (number of applications). We have continued treatments and samplings to confirm what we have previously reported. We do see again a very strong induction of immunity-related gene expression around 5 days after brassinosteroid treatment. After 9 months (with a monthly application), 60% of these trees are still HLB-negative and with a denser foliage, in part due to a more abundant flushing in May than the control-infected trees. Interestingly, we do see more synchronous flushing in trees treated with Brs as compared to controls. Trees treated with Brs had a massive flushing in June, whereas control trees had a more spread flushing in June and July. We are following this flushing dynamics in fall to confirm that Brs can synchronize flushing.2, To determine the best time of application (frequency) to achieve maximum protection against pests and disease in newly planted trees. We started the assesment of treatments after May flush, and we collected data on psyllid population, egg deposition and bacteria titer. We do see less psyllids and eggs per tree. We are now analyzing bacteria titer in samples collected through the first year. 3, To determine the effect of Br application on advancing fruit maturation in both Valencia and Hamlin. We have continued juice analysis of samples collected through the year. Treatments are planned to start in September for Hamlin and January in Valencia. We have prepared the experimental area in Duda, flagged the trees and collected baseline data (canopy, fruit set, tree height) as we are using the same trees than last year, so we can also assess any cummulative effects of treatment over time. Outreach:-Alferez, F., Shahid, M. (2023). Can brassinosteroids help citrus to cope with disease and extreme weather events? Citrus Industry, 104, 4 April 2023.-Alferez, F. Use of Auxins and Brassinosteroid in citrus to improve fruit growth and development. In Service Training Use of plant growth regulators in Florida horticulture industry. Daytona Beach, FL. June 13, 2023. 2. Please state what work is anticipated for next quarter: Treatments will start in Hamlin. 3. Please state budget status (underspend or overspend, and why): Spending is on track
1. Please state project objectives and what work was done this quarter to address them: 1. 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. Major activities in this quarter were leaf sampling of tagged flush, nutrient analysis, leaf characteristics documentation. A signifcant portion of time was spent on data analysis as we have a massive data set. The preliminary analysis is showing that the fertilization based on spring flush yielded the highest fruit. It is possible because spring flush is monitored throughout the year and therefore, fertilizer can be adjusted atleast three times. We are also learning about the leas charateristic differences between spring and summer flush where summer flush seems to be larger and more productive. Lastly, fruiting and non fruiting branch comparison are showing distinct nutrient profile differences between the two branches. These results will be presented at ASHS 2023 as an oral presentation. 2. Please state what work is anticipated for next quarter: 1. Data analysis and interpretation 2. Final leaf collection for phenotyping and nutrient analysis. 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. 4. Please show all potential commercialization products resulting from this research, and the status of each: Changes in leaf sampling recommedation will happen as a result of this research. We anticipate to have recommendations by december 2023.
1. Please state project objectives and what work was done this quarter to address them: 1. 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 final leaf sampling was done for nutrient analysis and leaf characteristics documentation. Other activities included data analysis as we have a massive data set. The preliminary analysis is showing that the fertilization based on spring flush yielded the highest fruit. It is possible because spring flush is monitored throughout the year and therefore, fertilizer can be adjusted atleast three times. The results from nutrient profile comparison of fruting and non fruiting branch were presented at ASHS 2023 as an oral presentation. The major finding of this objective are that the fruting branch show severe deficiency of macro nutients as the fruit matures whereas the micronutrient depletes in non fruiting branch as the season progresses. 2. Please state what work is anticipated for next quarter: 1. Data analysis and interpretation 2. Developing recomendations for nutrient analysis 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. 4. Please show all potential commercialization products resulting from this research, and the status of each: Changes in leaf sampling recommedation will happen as a result of this research. We anticipate to have recommendations by december 2023.
1. Please state project objectives and what work was done this quarter to address them: Objective 1: To compare different rates and annual use patterns of trunk-injected OTC on late-season (Valencia) and early-season (Hamlin) sweet orange tree and their effects on health, yield, and fruit quality over a period of 3 years in a commercial citrus production environment.Obective 2: To compare spring with late summer injections in Valencia orange trees to determine if OTC effects on yield can be enhanced, and the harvest window extended, through timing of injections. Two field trials were established in collaboration with Peace River Packing Company, one with Valencia (Varner grove – trial 1) and one with Hamlin (Kurish south grove – trial 2) trees. Trees in both groves were planted in 2005. Trial 1 was established in a split-plot design. The main plot factor is the season of injection at 2 levels: (i) spring injections; and (ii) late summer/fall injections. The sub-plot factor is the injection rate in combination with different annual use patterns as outlined below: Year 1 Year 2 Year 3 1 utc utc utc 2 150% 0 tbd 3 100% 100% 0 4 100% 0 100% 5 75% 75% 0 6 75% 0 75% 7 50% 50% 0 8 50% 0 50% The trial was established in 16 rows of trees, with the main plot factor arranged by row. Eight replications were used, with each replication consisting of 4 trees. The total number of experimental trees is 512 (8 treatments x 4 trees x 8 reps x 2 times). Spring injections were conducted on June 15 using ReMedium and the Flexinject injectors. The OTC solution was prepared directly in the field to prevent degradation. Trees were injected between 9-12 am. Trial 2 was established in a complete randomized block design using the same rate and annual use pattern as in the Valencia trial. The trial was established in 10 rows, each comprising one block, for 10 replications. Each replicate consist of 3 trees. The total number of experimental trees is 240 (8 treatments x 3 trees x 10 reps). Injections were conducted on June 1 using ReMedium and the Flexinject injectors. The OTC solution was prepared directly in the field to prevent degradation. Trees were injected between 9-12 am. 2. Please state what work is anticipated for next quarter: We will complete the September injections in trial 1. 3. Please state budget status (underspend or overspend, and why):The budget is as expected.
1. Please state project objectives and what work was done this quarter to address them: Objective 1: Study the changes in the reactive oxygen species (ROS) and investigate the correlation between ROS accumulation, sucrose levels and callose deposition in early season sweet oranges Budded trees from Hamlin, Parson Brown and Roble sweet oranges have been infected with CaLas through stick grafting. Initial qPCR results indicate that 80% of the trees infected have tested positive for Clas. Samples will be obtained from trees during November for further investigations. We will also sample trees from stakeholder plots for comparison with the greenhouse evaluation. Objective 2: Quantify fruit drop and canopy yield efficiency in Parson Brown as compared to Hamlin. Understand the underlying mechanism of better fruit retention and yield efficiency in Parson Brown as compared to Hamlin. This experiment has been initiated and trees have been tagged at a grower – cooperator plot. Objective 3: Determine the mechanism underpinning the tolerance of Parson Brown to HLB by leaf volatiles and non-volatile metabolite analysis using GC-MS. The metabolite and leaf voliatile assay has been completed and the results are being analysed. Objective 4: Evaluate other early season sweet oranges We have sampled our experimental trees once and subsequent leaf samples will be collected in the Fall (November) for this objective. 2. Please state what work is anticipated for next quarter: Fruit drop studies will be intiated on field trees. Also, results obtained in objective 3 will be analysed in detail. 3. Please state budget status (underspend or overspend, and why): We are on track with the budget now. A postdoc has been hired to work on several of the parameters in this project from the second quarter.
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