This is the first year of a three-year project. This overall 3 year project will focused on determining the optimum combination of chemotherapy, thermo-therapy, and nutrient therapy that can be registered for use in field citrus and control HLB. In this quarter (Oct 2014 to Dec 2014), we evaluated the efficiency of chemical compounds (Amp and silver dyne) against Las bacterium to combat HLB disease by gravity bag infusion. In our previous study, Al(OH)3 was difficult to be absorbed in citrus trees due to its low solubility in water. Therefore, in this quarter, Al(OH)3 was replaced in the field trial by silver dyne (SD), which was effective in the graft-based test in the greenhouse. The preliminary results indicated that Amp could suppress HLB bacterial titer in several citrus rootstocks after about one year, and SD had no significant effect on reducing HLB bacterial titer, 2 months after initial treatment. Because HLB bacterial titers in various citrus rootstocks were different in response to chemical compound, we continue to evaluate effect of Amp and SD against HLB bacterial in the future. Meanwhile, agronomic performance of treated trees will be investigated, and the nutrition and heat treatment therapy with several additional molecules will be conducted in next quarter.
Three growers agreed to apply 1/4th the regular rate of Citrus Fix (2, 4-D) and MaxCel (cytokinin) every 45 days on approximately 1 acre each of Hamlin and Valencia orange trees. Grove locations are Sebring, Babson Park and Ft. Meade. One grower applied an application early spring of 2014 while the other two growers waited until the crop was harvested so that they would not be subjected to crop destruct rules for the 2013-14 year’s crop. The last application for the growing season occurred in October, 2014. Comparable control rows are being monitored two rows from the sprayed trees. Treated and Control trees were categorized as to tree health and are monitored for fruit drop, flushing, yield, etc. No apparent differences in flushing pattern were detected during the summer flush. Tree condition (decline status) was evaluated at the end of the fall period. Fruit drop was measured and yields obtained for the Hamlin blocks. Yields were not different for year one, but fruit drop was numerically less for the treated trees by 3 % compared to the Control plots at one site where the data is analyzed. All Hamlin blocks have now been harvested. Flowering is being checked for any difference in timing or intensity. Valencia yields and drop as well as flowering are being evaluated under a new project contract with CRDF. Applications of Citrus Fix, Maxcel and including ProGibb this growing season have started for the second year. Growers have been diligent in making timely applications. Details of flowering and harvest yields for Hamlin orange plots will be in the March report for year 2.
Four growers agreed to treat Valencia plots of one acre each with Citrus Fix (2, 4-D) and Retain (AVG) at five locations. Treatments were applied using 2.8 fl. oz. of 2, 4-D or 100 gm ai/acre of Retain. Two locations were harvested almost immediately after application so that no data was obtained for these locations. The three remaining tests were treated on 2/11 (Lake Placid), 2/13 (east Lake Wales) or 2/19/2014 (Sebring). There was no significant difference between the PGRs, 2, 4-D and Retain, and the Control in any of the 3 trials. Overall preharvest drop rates were 25 to 35, 40 to 45 and 50 to 55 % for the three groves. In two of the groves the treatments had almost 5 % more drop than the Control, while at the other location the Control had almost 5 % more drop than the treatments. In the grove with less fruit drop for the treated trees (East Lake Wales), there was 6 % less drop in mild HLB decline trees and 8 % less drop in nearly healthy trees compared to similar Control trees. There was no difference between Control and treated trees that were more severely declining. The Control trees had 48, 59 and 59 % drop for healthy, mild and severely declining trees, respectively. The other two grower tests (east of Lake Placid and north of Sebring) had 3 to 4 % more drop in treated trees, both Citrus Fix and Retain, than the Control trees. These differences were not significant. The Control trees averaged 29 and 41 % fruit drop, and again the healthiest trees had 6 and 21 % less drop than declining trees for these two grower tests. These tests did not support the idea that 2, 4-D could consistently reduce preharvest drop associated with HLB disease when applied in late January. They did support the idea that more declined HLB trees will usually drop more of their fruit than declining trees before harvest.
Two trials were established that included sprays of Citrus Fix (2..8 floz/ac), Retain (100 g ai/ac), S-ABA (100g,ai/ac), 1-MCP (company determined rate) and the Control. These locations were Auburndale and Lake Wales. A third location did not include 1-MCP. The treatments at the first two mentioned tests were applied from February 10 to 12, 2014, while the third location (Lake Alfred) was treated earlier and twice (September and October). The preharvest drop values at the Lake Alfred site were low on January 25th (5 % drop) but increased to 18-30 % depending on treatment by harvest on March 25th. The ProGibb and ProGibb + Citrus Fix had the lowest fruit drop, but the values were not significantly different than the control. The other 2 sites had ranges of 33 to 37 % drop and 47 to 58 % drop between all the treatments, not significantly different. Consistent with all of the other tests, healthier trees had lower drop rates than more severely declined trees (20 % versus 30 and 34 % for mild and severely declined trees, respectively, at Lake Alfred). In another grove the % drop values ranged from 30-50 % for healthier trees and 50 to 70 % for mild and severely declining trees. In all cases differences between treatments and the Control were not significant probably partly due to tree condition within the plots. After these trials, plot sizes were increased to 10 trees.
Test groves were arranged with 5 growers with 11 different tests, 4 of which were sprayed by growers. Seven tests were in Hamlin blocks and 5 are in Valencia blocks. Materials included in tests are Citrus Fix (2, 4-D). Pro-Gibb (GA3), Headline, Gem, Abound and a PGR extract (Ascend) that contains an auxin, GA and cytokinin. Hamlin tests were applied in September or October and Valencia tests in November or December. Data collection includes preharvest fruit drop, total yield and juice analysis on some tests. Hamlin trials are complete and a grapefruit trial has initial results. Some grower applied trial results are as follows: In one trial ProGibb + Citrus Fix reduced drop 8 % over the Control which had 27 % drop. Ascend reduced drop 17 % compared to its Control with 42 % drop. In this trial Headline had no effect. In another trial Headline reduced drop 3.5 % over the Control rate of 26.5 in healthier trees but in declining trees Headline had no effect. In a grapefruit trial initial data found no effect of Headline, but ProGibb, Citrus Fix and the two combined had 11, 13 and 14 % drop, respectively, compared to 20 % drop in the Control. In small plot trials, 2, 4-D reduced drop of healthier and declining trees compared to the Control as did GA and GA + 2, 4-D combined for the declining trees. Neither Headline nor Ascend had an effect on fruit drop in this trial. In an 8 treatment trial near Auburndale, FL no treatment reduced fruit drop compared to the Control. In a trial near Dundee 2, 4-D + GA (18 % drop) and Headline (19 % drop) reduced drop compared to the Control which had 28.5 % drop. In a trial near Frostproof, two formulas of 2, 4-D and ProGibb + Citrus Fix combine reduced fruit drop to 20.5, 17.5 and 14.5 %, respectively, compared to the Control drop rate of 27 %. Data collection for several Valencia trials is now underway. For the Hamlin trials either the traditional GA and/or 2, 4-D or Headline reduced fruit drop about . the time. No factor(s) were obvious as to why they did or did not work in any given instance.
Test groves were arranged with 5 growers with 11 different tests, 4 of which were sprayed by growers. Seven tests were in Hamlin blocks and 5 are in Valencia blocks. Materials included in tests are Citrus Fix (2, 4-D). Pro-Gibb (GA3), Headline, Gem, Abound and a PGR extract (Ascend) that contains an auxin, GA and cytokinin. Hamlin tests were applied in September or October and Valencia tests in November or December. Data collection includes preharvest fruit drop, total yield and juice analysis on some tests. Hamlin trials are complete and a grapefruit trial has initial results. Some grower applied trial results are as follows: In one trial ProGibb + Citrus Fix reduced drop 8 % over the Control which had 27 % drop. Ascend reduced drop 17 % compared to its Control with 42 % drop. In this trial Headline had no effect. In another trial Headline reduced drop 3.5 % over the Control rate of 26.5 in healthier trees but in declining trees Headline had no effect. In a grapefruit trial initial data found no effect of Headline, but ProGibb, Citrus Fix and the two combined had 11, 13 and 14 % drop, respectively, compared to 20 % drop in the Control. In small plot trials, 2, 4-D reduced drop of healthier and declining trees compared to the Control as did GA and GA + 2, 4-D combined for the declining trees. Neither Headline nor Ascend had an effect on fruit drop in this trial. In an 8 treatment trial near Auburndale, FL no treatment reduced fruit drop compared to the Control. In a trial near Dundee 2, 4-D + GA (18 % drop) and Headline (19 % drop) reduced drop compared to the Control which had 28.5 % drop. In a trial near Frostproof, two formulas of 2, 4-D and ProGibb + Citrus Fix combine reduced fruit drop to 20.5, 17.5 and 14.5 %, respectively, compared to the Control drop rate of 27 %. Data collection for several Valencia trials is now underway. For the Hamlin trials either the traditional GA and/or 2, 4-D or Headline reduced fruit drop about . the time. No factor(s) were obvious as to why they did or did not work in any given instance.
Test groves were arranged with 5 growers with 11 different tests, 4 of which were sprayed by growers. Seven tests were in Hamlin blocks and 5 are in Valencia blocks. Materials included in tests are Citrus Fix (2, 4-D). Pro-Gibb (GA3), Headline, Gem, Abound and a PGR extract (Ascend) that contains an auxin, GA and cytokinin. Hamlin tests were applied in September or October and Valencia tests in November or December. Data collection includes preharvest fruit drop, total yield and juice analysis on some tests. Hamlin trials are complete and a grapefruit trial has initial results. Some grower applied trial results are as follows: In one trial ProGibb + Citrus Fix reduced drop 8 % over the Control which had 27 % drop. Ascend reduced drop 17 % compared to its Control with 42 % drop. In this trial Headline had no effect. In another trial Headline reduced drop 3.5 % over the Control rate of 26.5 in healthier trees but in declining trees Headline had no effect. In a grapefruit trial initial data found no effect of Headline, but ProGibb, Citrus Fix and the two combined had 11, 13 and 14 % drop, respectively, compared to 20 % drop in the Control. In small plot trials, 2, 4-D reduced drop of healthier and declining trees compared to the Control as did GA and GA + 2, 4-D combined for the declining trees. Neither Headline nor Ascend had an effect on fruit drop in this trial. In an 8 treatment trial near Auburndale, FL no treatment reduced fruit drop compared to the Control. In a trial near Dundee 2, 4-D + GA (18 % drop) and Headline (19 % drop) reduced drop compared to the Control which had 28.5 % drop. In a trial near Frostproof, two formulas of 2, 4-D and ProGibb + Citrus Fix combine reduced fruit drop to 20.5, 17.5 and 14.5 %, respectively, compared to the Control drop rate of 27 %. Data collection for several Valencia trials is now underway. For the Hamlin trials either the traditional GA and/or 2, 4-D or Headline reduced fruit drop about . the time. No factor(s) were obvious as to why they did or did not work in any given instance.
Three growers are appling1/4th the regular rate of Citrus Fix and MaxCel every 45 days on approximately 1 acre each of Hamlin and Valencia orange trees. Grove locations are Sebring, Babson Park and Ft. Meade. The last applications for this growing season are scheduled for October. Growers have been diligent in making timely applications. Fruit drop will be measured and yields obtained for Hamlin blocks. If further support is provided for this project, Valencia yields and drop as well as flowering will be checked for any difference in timing or intensity and applications will be made for a second year.
No additional treatments or data collection occurred during this period. Data will be summarized in the final report.
There were no additional tests or measurements during this period. Results will be summarized in the Final Report for the project.
Test groves were arranged with 5 growers with 11 different tests 4 of which will be sprayed by growers. Seven tests are in Hamlin blocks and 5 are in Valencia blocks. Materials included in tests are Citrus Fix (2, 4-D). Pro-Gibb (GA3), Headline, Gem, Abound and a PGR extract that contains an auxin, GA and cytokinin. Hamlin tests were applied in September or October and Valencia tests in November or December. Data collection will include preharvest fruit drop, total yield and juice analysis on some tests particularly if Headline is included.
Low concentrations (1/4 rate) of 2, 4-D and Max-Cel were applied every 45 days to Hamlin and Valencia tree canopies at two locations in central Florida starting in Spring 2014. Concentrations were 12.6 ml Citrus Fix and 480 ml Max-Cel. Every other 45 day period, GA3 (0.04 g ai/tree) was applied in 3 gal of water per each microjet irrigation zone. Treatments were applied from Spring through October. Trees were sampled in late spring for phloem development at four locations in the scaffold system (root flare, trunk, small scoffolds and leaf main veins). Comparable samples will be taken at the end of the growing season to compare phloem development with and without the PGR treatment. Comprehensive PGR profiles on the treatments were run by Dr. Killiny. Almost all of the treatment trees were positive for HLB. Fruit drop and fruit per tree data are now being collected. Root densities and canopy condition will also be evaluated.
The person to redo the Internet model for flowering evaluation was identified and hired to start work in December. Data collection and rewriting code will be done from December through January. Off season blooms related to HLB stresses are a problem that needs to be dealt with. We will try to program them if their induction relates to mild or moderate water stress periods.
This project, in general, seeks to determine if there are any observable influences of foliar fertilizers on HLB-affected grapefruit in the Indian River marketing district. To-date, this project has established 3 separate research trials in commercial grapefruit groves and university research farms in St. Lucie county, Florida. Trial #1 is ~25 years old of ‘Flame’ grapefruit on Swingle rootstock. Trial #2 utilizes ~6 year old ‘Ruby Red’ on Sour orange trees. The first 2 trials are located in commercial groves. Trial #3 seeks to determine the effect(s) that foliar fertilizers have on young tree growth and their ability to protract HLB disease symptoms in 1 year old ‘Ray Ruby’ grapefruit on Kuharske rootstock. For trial #1, there are a total of 30 replicated experimental units; for trial #2, there are a total of 50 replicated experimental units; and, for the trial #3, there are a total of 24 replicated experimental units. Foliar fertilizer applications have been started since February 2014. Tree growth data, leaf nutrition data, and CLas titer measurements have been made. Fruit drop monitoring will begin in September 2014 in trials #1 and #2. In prosecution of these efforts, 2-part-time OPS employees have been hired to do our foliar sprays and collect data observations. We also completed the refurbishment of a mobile fruit grading line. Fruit quality and quantity assessments will begin in late fall/early winter of 2014.
The insectary at the Florida Department of Agriculture and Consumer Services, Division of Plant Industry (DPI) was a longstanding source of Diaprepes root weevil larvae for researchers in Florida and elsewhere. Reduced demand for these larvae caused this agency to discontinue their production in September 2014. In anticipation we met several times with the agency to learn their methodology. We purchased cages and supplies and constructed an insectary, acquired adult weevils and began rearing larvae on diet in axenic conditions. To date we have produced 4 ‘production runs’. Contamination of cultures in which the larvae grow has been a problem, but fewer units have become contaminated over time. We will have enough 3-5 instar larvae going into the winter season to conduct the upcoming field trials at sites in Lake and Polk Counties. Repeated experiment using H. floridensis, validating results reported in previous report. We shall include H. floridensis in upcoming field trials.
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