Controlling citrus greening in citrus plants using a combination of oxytetracycline and streptomycin

Abstract

The present disclosure relates generally to methods and systems for controlling citrus greening disease in citrus plants, including for example orange trees. In some embodiments, the method comprises injecting into the tree an injection formulation comprising a combination of oxytetracycline and streptomycin.

Description

CONTROLLING CITRUS GREENING IN CITRUS PLANTS USING A COMBINATION OF OXYTETRACYCLINE AND STREPTOMYCINCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to United States Provisional Patent Application No. 63 / 472,401, filed June 12, 2023, which is hereby incorporated herein by reference in its entirety.FIELD

[0002] The present disclosure relates generally to methods of controlling citrus greening in citrus plants.BACKGROUND

[0003] Citrus huanglongbing (HLB), also known as citrus greening disease, is one of the most destructive diseases of citrus worldwide. Citrus greening is generally caused by phloemcolonizing bacterium, such as 'Candidal us Liberibacter asiaticus’ (CLas). There are three forms of greening that have been described. The African form is transmitted by the African citrus psyllid Trioza erytreae, and produces symptoms under cool conditions. The Asian and American forms are transmitted by the Asian citrus psyllid Diaphorina citri, and produce symptoms under warmer conditions. For example, since 2005, HLB has spread through the citrus-producing areas in Florida, reducing citrus production by 75% while more than doubling the cost of production.

[0004] The bacteria causing citrus greening can infect most citrus cultivars. For example, newly infected trees develop leaves with a blotchy appearance. Chronically infected trees develop leaves that are small and exhibit asymmetrical blotchy mottling. Fruit from infected trees tend to be small and have a poor quality. The juice from such fruit tends to have a low soluble solids content, and taste acidic and bitter. There is currently no practical or commercially available cure for the disease. As such, to prevent the spread of citrus greening, rapid tree removal is usually required.

[0005] Thus, what is desired are commercially viable treatment solutions for controlling citrus greening.BRIEF SUMMARY

[0006] In one aspect, provided are methods for controlling citrus greening of a citrus plant, such as a citrus tree or a citrus bush. In some embodiments, the method comprises injecting the infected citrus plant with an injection formulation comprising a tetracycline antibiotic and an aminoglycoside antibiotic. In some embodiments, the tetracycline is oxytetracycline (OTC). In some embodiments, the aminoglycoside is streptomycin. In some embodiments, the injecting of the injection formulation is performed using an injection system comprising an injection tool. In some embodiments, the injection tool is operatively connected to a fluid delivery unit. In some embodiments, the fluid delivery unit is configured to deliver the injection formulation.

[0007] In some embodiments, the injecting of the injection formulation comprises piercing the trunk or stem of the citrus plant using the injection tool of the injection system. In some embodiments, the injecting of the injection formulation comprises delivering at least a portion of the injection formulation from the fluid delivery unit through the injection tool into at least the active vasculature of the citrus plant.

[0008] In some embodiments, the citrus plant is suffering from citrus greening disease. In some embodiments, the injection formulation is distributed throughout the trunk or stem, and other parts of the citrus plant, such as the leaves and / or fruits. In some variations, the injection formulation is precisely injected into the scion of the citrus plant. In some embodiments, the citrus plant is at least about 1, at least about 2, at least about 3, at least about 4, at least about 5, at least about 10, at least about 15, at least about 20, at least about 30, at least about 40, or at least about 50 years old.

[0009] In some embodiments, the delivery unit is a spring-loaded fluid delivery unit. In some embodiments, the delivery unit comprises a pressurized formulation cartridge. In some embodiments, the method comprises replacing the fluid delivery unit with a second fluid delivery unit. In some embodiments, the method comprises delivering at least a portion of the injection formulation from the second fluid delivery unit through the injection tool into at least the active vasculature of the citrus plant.

[0010] In some embodiments, the injection tool remains in the trunk or stem (including the scion) of the citrus plant over at least one growing season. In some embodiments, the injection tool remains in the trunk or stem (including the scion) of the citrus plant to facilitatemultiple applications of the injection formulation. In some embodiments, the injection tool is slightly repositioned to facilitate multiple applications of the injection formulation. In some embodiments, the trunk or stem of the citrus plant has bark. In some embodiments, the method comprises removing at least a portion of the bark prior to piercing the trunk.DESCRIPTION OF THE FIGURES

[0011] The present application can be understood by reference to the following description taken in conjunction with the accompanying figures.

[0012] FIGS. 1A-1C depict an exemplary injection tool.

[0013] FIGS. 2A-2D depict an exemplary multi-port injection tool.

[0014] FIG. 3 depicts an exemplary spring-loaded fluid delivery unit.

[0015] FIG. 4A depicts an exemplary chassis.

[0016] FIG. 4B depicts an exemplary canister.DETAIEED DESCRIPTION

[0017] The following description is presented to enable a person of ordinary skill in the art to make and use the various embodiments. Descriptions of specific devices, techniques, and applications are provided only as examples. Various modifications to the examples described herein will be readily apparent to those of ordinary skill in the art, and the general principles defined herein may be applied to other examples and applications without departing from the spirit and scope of the various embodiments. Thus, the various embodiments are not intended to be limited to the examples described herein and shown, but are to be accorded the scope consistent with the claims.

[0018] In some aspects, provided here are methods for controlling citrus greening disease in a citrus plant. In some embodiments, citrus greening disease in these citrus plants are controlled by precisely injecting a liquid formulation comprising a combination of (i) a tetracycline antibiotic or a salt thereof and (ii) an aminoglycoside antibiotic or a salt thereof into the active vasculature of the plant. In some variations, the liquid formulation is injected at least the active vasculature of the plant. In some embodiments, the tetracycline antibiotic is oxy tetracycline. In some embodiments the aminoglycoside antibiotic is streptomycin. Thesystems used in the methods described herein minimize the amount of leakage of the oxytetracycline and streptomycin into the surrounding environment.Injection formulations

[0019] In one aspect, provided are injection formulations suitable for use in controlling citrus greening in a citrus plant. In certain embodiments, the injection formulation is water soluble. In some embodiments, the injection formulation comprises a combination of (i) a tetracycline antibiotic or a salt thereof and (ii) a aminoglycoside antibiotic or a salt thereof. In some embodiments, the tetracycline antibiotic is oxy tetracycline. In some embodiments the aminoglycoside antibiotic is streptomycin. In one variation, the oxytetracycline salt is a HC1 salt. In certain variations, the injection formulation further comprises nutrients. In one variation, the injection formulation comprises micronutrients.

[0020] In some embodiments, the injection formulation comprises a stock formulation or a commercially available formulation. In some embodiments, the injection formulation comprises a stock formulation diluted with water or other solvents or formulations. In some embodiments, the injection formulation comprises a commercially available formulation diluted with water or other solvents or formulations. In some embodiments, stock formulations comprise commercially available formulations. In some variations, commercially available formulations or stock formulations may be diluted and / or further formulated for use in the methods described herein.

[0021] In some embodiments, the OTC or a salt thereof is present in the injection formulation at a concentration of between about 0.6 mg / mL and about 0.7 mg / mL. In some embodiments, the OTC or a salt thereof is present in the injection formulation at a concentration of between about 0.1 mg / mL and about 10 mg / mL, between about 0.1 mg / mL and about 5 mg / mL, between about 0.1 mg / mL and about 2.5 mg / mL, between about 0.1 mg / mL and about 2 mg / mL, between about 0.1 mg / mL and about 1.5 mg / mL, between about 0.1 mg / mL and about 1 mg / mL, between about 0.25 mg / mL and about 1 mg / mL, between about 0.25 mg / mL and about 0.75 mg / mL, between about 0.5 mg / mL and about 0.75 mg / mL, or between about 0.6 mg / mL and about 0.7 mg / mL. In some embodiments, the OTC or a salt thereof is present in the injection formulation at about 0.6 mg / mL. In some embodiments, the OTC or a salt thereof is present in the injection formulation at a concentration of about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 mg / mL.

[0022] In some embodiments, the streptomycin or a salt thereof is present in the injection formulation at a concentration of between about 2.25 mg / mL and about 2.75 mg / mL. In some embodiments, the OTC or a salt thereof is present in the injection formulation at a concentration of between about 0.1 mg / mL and about 10 mg / mL, between about 0.1 mg / mL and about 7.5 mg / mL, between about 0.1 mg / mL and about 5 mg / mL, between about 0.5 mg / mL and about 5 mg / mL, between about 1 mg / mL and about 5 mg / mL, between about 2 mg / mL and about 5 mg / mL, between about 2 mg / mL and about 4 mg / mL, between about 2 mg / mL and about 3 mg / mL, or between about 2.25 mg / mL and about 2.75 mg / mL. In some embodiments, the streptomycin or a salt thereof is present in the injection formulation at about 2.5 mg / mL. In some embodiments, the streptomycin or a salt thereof is present in the injection formulation at a concentration of about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1,I.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, or 10 mg / mL.

[0023] In certain variations, the relative concentrations of OTC to streptomycin, or salts thereof, is between about 1:3 and about 1:5. In some embodiments, the relative concentrations of OTC to streptomycin, or salts thereof, is between about 1:0.1 and about 1:50, between about 1:0.5 and about 1:20, between about 1:1 and about 1:10, between about 1:1 and about 1:7.5, between about 1:1 and about 1:5, between about 1:2 and about 1:5, between about 1:3 and about 1:5, or between about 1:3.5 and about 1:4.5.

[0024] In certain variations, the relative concentrations of OTC to streptomycin, or salts thereof, is about 1:4. In some embodiments, the relative concentrations of OTC to streptomycin, or salts thereof, is about 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:7, 1:8, 1:9, or 1:10.Treatment Protocol

[0025] In some embodiments, the method comprises injecting the citrus plant with an injection formulation described herein.

[0026] In some embodiments, injecting the injection formulation or any of the methods described herein are performed 4 times a year. In some embodiments, injecting the injection formulation or any of the methods described herein are performed 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,I I, or 12 times a year. In some embodiments, injecting the injection formulation or any of the methods described herein are performed more than 1 time, more than 2 times, more than 3 times, more than 4 times, more than 5 times, more than 6 times, more than 7 times, more than8 times, more than 9 times, or more than 10 times a year. In some embodiments, injecting the injection formulation or any of the methods described herein are performed less than 2 times, less than 3 times, less than 4 times, less than 5 times, less than 6 times, less than 7 times, less than 8 times, less than 9 times, or less than 10 times a year.Citrus Plant & Diseases

[0027] In some embodiments, the citrus plant is a citrus tree or a citrus bush. In some variations, the citrus tree is an orange tree, a lemon tree, a lime tree, a grapefruit tree, or a pomelo tree. In certain variations, the citrus plant is a lemon bush, or a lime bush. In one variation, the citrus bush is a dwarf citrus bush. In other variations, the citrus tree is a mature tree.

[0028] In some variations, the citrus plants are suffering from citrus greening disease caused by Liberibacter spp. (e.g., L. asiaticus, L. africanus, L. americaniis). In some variations, the disease is transmitted by the Asian citrus psyllid, Diaphorina citri, and the African citrus psyllid, Trioza erytreae.

[0029] In some embodiments, the infected citrus plant exhibits at least one symptom caused by citrus greening disease. In some embodiments, the citrus plant to which the injection formulation is applied is infected. In some embodiments, the citrus plant to which the injection formulation is applied is not infected. In some embodiments, the methods described herein are used only for citrus plants with one or more symptoms caused by citrus greening disease. Such symptoms may include any one or more of the following: asymmetrical yellowing of veins and adjacent tissues; splotchy mottling of the entire leaf; premature defoliation; dieback of twigs; decay of feeder rootlets and lateral roots; decline in vigor; stunted growth, bear multiple off-season flowers; produce small, irregularly shaped fruit with a thick, pale peel that remains green at the bottom and tastes bitter.

[0030] In some variations, to assess the efficacy of the injection formulations used in the citrus plant, one or more of the following are evaluated: Brix analysis of fruit, fruit yield, fruit drop, OTC and / or streptomycin residue levels in fruit, OTC and streptomycin concentrations in citrus leaves, effects of the treatment on CLas titers in leaves, and overall plant health. Fruit yield can be determined, for example, by the total weight of the fruits produced by a tree, or by the numbers of fruits produced by a tree.

[0031] In some embodiments, this disclosure provides methods for enhancing or maintaining plant health in the citrus plants and grove. In some such embodiments, this disclosure provides methods for treating diseased plants and / or methods for controlling the bacteria, fungi, viruses and / or other pathogens that cause citrus greening disease in the citrus plants. In further such embodiments, this disclosure provides methods for treating citrus plants whose xylem and / or phloem have been invaded by disease-causing bacteria, fungi, viruses, and / or other pathogens, for controlling the bacteria, fungi, virus and / or other pathogens causing the disease, and for preventing diseases by preventing sufficient colonization of the plant by the disease causing pathogens such as bacteria, fungi, and viruses.

[0032] In some embodiments, controlling citrus greening disease in citrus plants using the systems, devices and methods herein includes reducing the bacterial concentration (titer) in the vascular system. In some variations, controlling citrus greening disease in citrus plants using the systems, devices and methods herein includes reducing the bacterial concentration (titer) in the vascular system by strengthening the plant’s natural defense system. In certain embodiments, the systems, devices and methods herein can provide a treatment that leads to suppression of the disease to a level where recovery of citrus production occurs. In some variations, bacterial titer refers to the bacterial concentration in the vascular system of the infected plant. Bacterial titer may be measured using any suitable methods and techniques known in the art. For example, in one variation, bacterial titer is measured through quantitative PCR. In one variation, CLas titer is measured, e.g., using any suitable techniques known in the art.

[0033] In some variations, the treatment protocols provided herein can (i) reduce fruit drop; (ii) increase Brix in the fruit; and / or (iii) increase fruit yield. In some embodiments, the treatment protocols provided herein can (i) reduce fruit drop by at least about 10%, (ii) increase Brix by at least about 5%, and / or (iii) increase fruit yield by at least about 10%. In certain variations, the treatment protocols provided herein can (i) reduce fruit drop by at least about 5%, 7.5%, 10%, 12.5%, 15%, 17.5%, 20%, 22.5%, 25%, 30%, 40%, or 50%, or between about 5% and about 50%, between about 5% and about 40%, between about 5% and about 30%, between about 5% and about 25%, between about 10% and about 25%, between about 15% and about 25%, or between about 17.5% and about 22.5%; (ii) increase Brix by at least about 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%, or between about 1% and about10%, between about 2% and about 9%, between about 2% and about 8%, between about 2% and about 7%, between about 2% and about 6%, or between about 3% and about 5%, and / or (iii) increase fruit yield by at least about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 150%, 200%, 300%, 400%, or 500%, or between about 5% and about 100%, between about 10% and about 100%, between about 20% and about 100%, between about 30% and about 100%, between about 40% and about 100%, between about 50% and about 100%, between about 60% and about 100%, between about 70% and about 100%, between about 80% and about 100%, or between about 80% and about 95%. Overall, in one variation, the treatment protocols provided herein can improve recovery of plant health, and yield a healthier, more resilient grove.

[0034] In some variations, the fruit collected from the plants to which the injection formulation is administered has an average OTC and / or streptomycin residue less than 0.01 ppm. In some variations, the fruit collected from the plants to which the injection formulation is administered has an average OTC and / or streptomycin residue less than 0.0001 ppm, less than about 0.001 ppm, less than about 0.01 ppm, less than about 0.015 ppm, less than about 0.02 ppm, less than about 0.025 ppm, less than about 0.03 ppm, less than about 0.04 ppm, or less than about 0.05 ppm, or no detectable levels of OTC and streptomycin. In other variations, the average OTC and / or streptomycin residue is between about 0.001 ppm and about 0.01 ppm.

[0035] In some variations, the average fruit drop for the plants to which the injection formulation is administered is less than about 20. In some variations, the average fruit drop for the plants to which the injection formulation is administered is less than about 25, less than about 20, less than about 15, or less than about 10; or between about 10 and about 25 or between about 10 and about 20.

[0036] In some variations, the average fruit yield for the plants to which the injection formulation is administered is at least about 45 lbs. In some variations, the average fruit yield for the plants to which the injection formulation is administered is at least about 35 lbs, at least about 40 lbs, at least about 45 lbs, at least about 50 lbs, at least about 55 lbs, at least about 60 lbs, at least about 65 lbs, at least about 70 lbs, at least about 75 lbs, at least about 80 lbs, or least about 85 lbs per plant, or between about 30 and about 90 lbs, or between about 35 and about 85 lbs per plant.

[0037] In some variations, an average Brix for the plants to which the injection formulation is administered is at least about 7.5. In some variations, an average Brix for the plants to which the injection formulation is administered is at least about 7.5, at least about 7.6, at least about 7.7, at least about 7.8, at least about 7.9, at least about 8, or at least about 8.5; or between about 7 and about 9, or between about 7.5 and about 8.5.

[0038] In other embodiments, controlling citrus greening disease in citrus plants using the systems, devices and methods herein includes at least partially or fully restoring phloem functionality of the infected citrus plants. In certain embodiments of the foregoing, this may restore the plant’s productive capacity and overall plant health including the metabolomic profile of the plant. In some variations, metabolomic profile of the plant may be used to measure the plant health.

[0039] In yet other embodiments, controlling citrus greening disease in citrus plants using the systems, devices and methods herein includes at least partially or fully restoring yield capacity. In some variations, yield over the plant lifecycle is increased as compared to untreated control plants.

[0040] In certain embodiments, the method comprises delivering a formulation comprising OTC and streptomycin, and optionally one or more nutrients, into a citrus plant. In certain embodiments the method comprises precision delivery (also referred to as “precision injection”) of a formulation into the citrus plant. Precision delivery refers to delivering the formulation only or substantially only into a target location in the citrus plant. For example, in some embodiments, the target location is the active vasculature of the plant. In certain embodiments, the method comprises injecting an injection formulation into at least the active vasculature of the plant. In some variations, the active vasculature of the plant is the xylem and / or the phloem. In one variation, the active vasculature is active xylem (such as sapstream) and phloem. In further embodiments, precision delivery involves delivering the formulation into the active vasculature of the citrus plant while minimizing damage to the plant relative traditional forms of injection drilling systems. In yet other embodiments, precision delivery involves using a system that can be configured to deliver formulation into at least the active vasculature of a plant.

[0041] In certain embodiments, the method comprises injecting an injection formulation comprising OTC and streptomycin into a citrus plant, for example into the active vasculatureof the plant using precision delivery devices and systems, such as those referenced herein. In some such embodiments, the methods comprise precise injection of an injection formulation comprising OTC and streptomycin into the plant. In certain embodiments, the methods comprise injecting an injection formulation, for example precise injection of an injection formulation, comprising OTC and streptomycin into the plant, for example into the active vasculature of the plant prone to disease caused by citrus greening disease.

[0042] In some embodiments, this disclosure also provides systems and devices for delivering injection formulations to the interior of the plant. In some embodiments, the systems comprise an injection tool operatively connected to a fluid delivery unit, wherein the injection tool is configured for precision delivery of the injection formulation to a target location inside the plant. In some embodiments, the systems are configured for precision delivery of an injection formulation into the active vasculature of a citrus plant. In some embodiments, the fluid delivery unit further comprises the formulation. In other embodiments, the system comprises an injection tool, a fluid delivery unit, and a source of source of formulation in fluid communication with the fluid delivery unit.Injection System

[0043] In some embodiments, the injecting of the injection formulation is performed using an injection system comprising an injection tool operatively connected to a fluid delivery unit, wherein the fluid delivery unit is configured to deliver the injection formulation. In some embodiments, the injecting of the injection formulation comprises piercing the trunk or stem of the citrus plant using the injection tool of the injection system. In some embodiments, the injecting of the injection formulation comprises delivering at least a portion of the injection formulation from the fluid delivery unit through the injection tool into at least the active vasculature of the plant.

[0044] In some embodiments, an injection system is used to deliver the injection formulation to a citrus plant. In some variations, the injection system comprises: an injection tool operatively connected to a fluid delivery unit. In certain variations, the injection tool comprises: a base having at least one inlet; and a body comprising at least one distribution reservoir, and at least one outlet. In some embodiments, the injection system comprises: an injection tool, a fluid delivery unit, and a source of active ingredient (including, for example, nutrients) formulated as a liquid.

[0045] In some variations, the body is shaped to pierce the plant, such as the trunk or stem of the plant. In certain variations, the body is in the shape of a blade. In certain variations, the body has a cutting edge at the tip of the body, and the width of the cutting edge is narrower than width of the body in the area connected to the base.

[0046] In certain variations, the body comprises: at least one outlet that receives the injection formulation from the at least one inlet, and at least one distribution reservoir that retains the injection formulation proximate to adjacent tissue of the plant. In certain variations, the fluid delivery unit is configured to store and deliver the injection formulation. In certain variations, the fluid delivery unit comprises a pressurized container (e.g., a pressurized canister).

[0047] In some embodiments, the method comprises: piercing the trunk or stem of a citrus plant using the injection tool of the injection system; and delivering at least a portion of the injection formulation from the fluid delivery unit through the injection tool to the vasculature of the citrus plant. In some variations, the injection formulation is delivered pneumatically or hydraulically.

[0048] In some embodiments, the injection formulation is precisely delivered. In some variations, the injection formulation is delivered into and at least the active vasculature of the plant when the injection tool is inserted into the trunk or stem of the plant. In one variation, the injection formulation is delivered into at least the xylem, or the phloem or both of the plant when the injection tool is inserted into the trunk or stem of the plant.

[0049] In other embodiments, precisely delivering the injection formulation comprises inserting the injection tool into at least the active vasculature of the plant. In certain variations, precisely delivering the injection formulation comprises inserting the body of the injection tool into at least the active vasculature of the plant. In one variation, precisely delivering the injection formulation comprises inserting the injection tool such that the distribution reservoir is positioned in at least the active vasculature of the plant.

[0050] In some variations, the methods deliver at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98% or at least about 99% of the injection formulation into to the active vasculature of the plant. In one variation, the methods deliver at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at leastabout 95%, at least about 96%, at least about 97%, at least about 98% or at least about 99% of the injection formulation into the xylem and / or phloem of the plant. In some variations of the foregoing, the methods deliver the injection formulation into to the active vasculature of the plant in an average maximum time of less than about 10 minutes, or less than about 5 minutes.

[0051] In certain embodiments, the method comprises injecting injection formulation into the vasculature through one or more sites on the trunk or stem of the plant. In embodiments where the formulation is injected through multiple injection sites, a plurality of the injection systems described herein may be used. In some embodiments where the formulation is injected through multiple injection sites, the system comprises multiple injection tools operatively connected to a single fluid delivery unit.

[0052] In some variations, the method further comprises removing at least a portion of the bark around the injection site, e.g., prior to piercing the trunk.

[0053] The methods described herein generally provide one or more commercial advantages over the methods currently known in the art to control citrus greening disease. For example, advantages include one or more of a faster return to the production yields preinfection, fast response (e.g., curing), lower volumes of formulation needed, less loss of formulation to the environment, less damage to the plant, response in old plants, response in plants with significant disease symptoms.

[0054] In embodiments, the injection systems comprise an injection tool, a fluid delivery unit, and an injection formulation source. In operation, the injection tool is operatively connected to the fluid delivery unit such that injection formulation flows from the source through the injection tool into the plant. In some embodiments, the source of injection formulation is independent of the fluid delivery unit. In other embodiments, the source of injection formulation is integral with the fluid delivery unit. Certain embodiment of injection systems suitable for use in the methods described herein are described in further detail below.Injection Tool

[0055] In some embodiments, the injection tool includes a body, at least a portion of which is designed to be lodged into the trunk or stem of a plant. The body has a channel system (e.g., having one or more channels) through which the injection formulation can flow.In some variations, the liquid formation enters the injection tool through one or more inlets, and exits the injection tool through one or more outlets through which the injection formulation is delivered to the interior of the plant. In some embodiments, the lodged portion of the body is sized and shaped to reduce or minimize damage to the target plant when inserted into the plant, while maintaining efficient functionality of the injection tool in delivering the desired dosing of the injection formulation over the desired time period directly to the sapwood and not the heartwood of the trunk of the plant. In other embodiments, the lodged portion of the body is sized and shaped to reduce damage to the target plant when inserted into the plant, as compared to traditional drilling injection system.

[0056] In some variations, exemplary injection tools are depicted in FIGS. 1A-1C and 2A-2D. With reference to FIGS. 1A-1C, depicted is an exemplary injection tool 6001 having a base 6010 and a body 6020. The body 6020 includes a cutting element. For example, in one variation, the body 6020 includes a cutting edge along the front face 6021, directed distally away from the base 6010. In some variations, the outlets 6027 and distribution reservoirs 6028 are within the body 6020. As shown in the side view of FIG. 3C, the body 6020 increases in thickness from the distal portion 6041 toward the proximal portion 6043 and the base 6010.

[0057] In some embodiments, the base 6010 optionally includes a ribbed outer structure6012, such as attachment cleats, to facilitate grasping of the base 6010 and to securely connect the injection tool 6001 with a fluid delivery unit. In some variations, at the transition between the base 6010 and the body 6020, a step is provided. The step forms an abutting face6013. The abutting face 6013 extends relative to (e.g., away from) the body 6020. During insertion of the injection tool 6001, the abutting face 6013 contacts the tree and arrests further advancement of the injection tool 6001 into the tree. In some variations, a larger abutting face 6013 facilitates use with smaller and less robust trees having a comparably soft shell or boundary. The relatively large abutting face distributes forces from insertion over the correspondingly large face 6013 and thereby minimizes trauma to the tree. In certain variations, the abutting face 6013 further provides an enclosing face for the injection tool 6001 for establishing a robust coupling with the tree.

[0058] As shown in FIGS. IB and 1C, the base 6010 includes an inlet 6011, which receives the injection formulation from the fluid delivery unit. The injection formulation travels through a main channel 6025, and is released through the outlets 6027 into thedistribution reservoirs 6028. As shown in FIGS. 1A and IB, outlets 6027 open transversely into the respective distribution reservoirs 6028.

[0059] The injection formulation is delivered from the outlets 6027 transversely, for instance relative to the longitudinal body axis 6040 and the corresponding insertion direction 6030, into the distribution reservoirs 6028. The distribution reservoirs 6028 retain the injection formulation in residence proximate to adjacent plant tissues. In the example shown in FIG. 3B, the outlets 6027 extend proximally toward the base 6010 and transverse relative to the insertion direction 6030 of the injection tool 6001.

[0060] Because of the relatively small profile of the injection tool 6001, the injection tool 6001 is readily inserted and installed in comparably small trees or less robust trees having a softer plant material (e.g., tissues or the like). For instance, the injection tool 6001 is configured for softened striking or manual pressing of the injection tool 6001 into the tree.

[0061] As shown in FIG. IB, the injection tool 6001 is inserted along an insertion direction 6030 corresponding to the longitudinal body axis 6040 of the injection tool 6001. The body 6020 of the injection tool 6001 spreads the tree material aside as the injection tool 6001 is inserted into the tree. Spreading of the tree material minimizes trauma to the tree material, and in some examples facilitates enhanced uptake of formulations.

[0062] As further shown in FIG. IB, the outlets 6027 extend in outlet direction 6032 toward the distribution reservoirs 6028. The outlet direction 6032 is transverse to the insertion direction 6030 (and the longitudinal body axis 6040). For example, in some variations, the outlet direction 6032 is misaligned with the insertion direction 6030 (and the longitudinal body axis 6040) with an angle of 125 degrees or the like. The transverse orientation of the outlets 6027 isolates the outlets 6027 from tree material otherwise introduced into the outlet channels with insertion. Further, the distribution reservoirs 6028 facilitate positioning of the outlets 6027 within the body profile, for instance recessing the outlets 6027 from an exterior of the body profile.

[0063] With reference to FIGS. 2A-2D, depicted is another exemplary injection tool 6101 having a base 6110 and a body 6120. The base 6110 and the body 6120 share similar features as described above for base 6010 and body 6120. For example, the body 6120 may include a cutting edge along the front face of the body. The body further includes outlets that distribute the injection formulation into distribution reservoirs 6128 within the body 6120.

[0064] However, unlike the injection tool 6001 depicted in FIGS. 1A-1C, injection tool 6101 has a base 6110 that includes two inlets 6111, which receives the injection formulation from the fluid delivery unit. The injection formulation travels through a main channel, and is released through the outlets into the distribution reservoirs 6128.

[0065] In some variations, the injection tool may have a plurality of inlets operatively connected to a fluid delivery unit. In certain variations, the injection tool has two, three or four inlets operatively connected to a fluid delivery unit.

[0066] With reference again to FIGS. 2A, 2B and 2D, the base 6010 optionally includes a ribbed outer structure, such as attachment cleats, to facilitate grasping of the base 6010 and to securely connect the injection tool 6001 with a fluid delivery unit.

[0067] In some embodiments, the injection systems described herein comprising the exemplary injection tools depicted in the figures do not require drilling a hole or installing a valve in the trunk or stem of the plant before injecting the injection formulation.Fluid Delivery Unit

[0068] In some embodiments, the fluid delivery unit and the source of the injection formulation are integrated into a formulation cartridge, such as a pressurized container. In certain variations, the formulation cartridge is a pressurized canister. In operation, the injection formulation flows from the fluid delivery unit through the injection tool into the plant. WO 2020 / 021041 and WO 2021 / 152093, each of which is hereby incorporated by reference, provides additional embodiments and variations of the injection systems and components thereof, including in the figures therein.

[0069] In some embodiments, the injection systems or components thereof used in the methods described herein are as depicted in the figures. In some embodiments, the systems are configured to administer injection formulation comprising one or more active ingredients (including, for example, nutrients) to a plant or a part thereof. In certain embodiments, such systems are mounted onto a post portion of a plant, for example to a trunk or stem of the plant.

[0070] In some embodiments, the methods provided herein include installing an injection tool in the trunk, stem, root or limb of a plant, operatively connecting the injection tool to afluid delivery unit, and activating the fluid delivery unit to initiate the flow of fluid from the fluid delivery unit through the injection tool and into the plant. In other embodiments, two or more injection tools are installed into one or more of the stem, trunk, roots, limbs or the like of a plant to minimize trauma to the plant (e.g., by minimizing the size of a unitary hole in the tree or spacing the tools apart along the plant). In some such embodiments, the two or more injection tools are operatively connected to the same fluid delivery unit. In other such embodiments the two or more injection tools are operatively connected to independent fluid delivery unit.

[0071] In some variations, the fluid delivery unit comprises a spring-loaded fluid delivery unit. In certain variations of the foregoing, the spring-loaded fluid delivery unit is configured to operate without substantially any pressure. In some embodiments, the spring-loaded fluid delivery unit is configured to operate at a pressure between 0.1 bar-3 bar. In some embodiments, the delivery unit operates between 1.5-3 bar. In other variations, the fluid delivery unit comprises a fluid delivery unit comprising a pressurized container (e.g., a pressurized canister). Examples of suitable fluid delivery unit include the variations depicted in FIGS. 3 and 4A.

[0072] With reference to FIG. 3, depicted is an exemplary spring-loaded fluid delivery unit 9900. Base 9912 holds two springs 9908 within syringes 9910. A piston with a rubber seal divides the injection formulation from the spring chamber. Attached to each syringe body 9910 is a tube 9904 connected to a t-shaped connector 9902. The injection tip (not depicted in FIG. 3) is connected to the connector 9902. The spring-loaded fluid delivery unit 9900 can be filled through connector 9902.

[0073] In other exemplary embodiments, the spring-loaded fluid delivery unit may have a base holding one or multiple springs within one or multiple corresponding syringes. The design of the spring-loaded fluid delivery unity may vary based on the pressure, volume, time or other appropriate parameters to deliver the injection formulation. For example, in some variations, multiple springs (such as a dual spring) may be employed in the fluid delivery unit to allow for injection of a higher volume of the injection formulation. In other variations, a single spring with a larger syringe may be used, but may affect pressure range employed to inject the injection formulation.

[0074] With reference to FIG. 4A, depicted is an exemplary chassis-style injection system comprising a system housing for integrating various components of the injection system, including an injection tool. Injection system 9800 includes a chassis 9802 that has a delivery interface connecting to the injection tool 9806. The delivery interface includes, but is not limited to, passages, channels, tubing, reservoirs or the like that interconnect the formulation cartridge (not depicted in FIG. 4A) and the injection tool 9806. The delivery interface extends to the injection tool and fluidly communicates the formulation to the distribution reservoirs of the injection tool. A flange 9880 may engage the formulation cartridge, resulting in activating the cartridge and maintaining it in place. In some embodiments, the position of the flange is adjustable to accommodate different length canisters and / or to permit activation at a desired time. As further depicted in FIG. 4A, in some embodiments, at least a portion of chassis includes a flexible portion 9882, for example to mitigate damage to the tip during installation. In one variation, in the exemplary injection system depicted in FIG. 4A, the chassis 9802 can further include an anchor 9890 to further facilitate coupling with the tree. For instance, a belt, strap or the like may be passed through the anchor 9890 to hold the injection system 9800 in place along the tree.

[0075] With reference to FIG. 4B, a pressurized formulation cartridge 9810 is depicted. The exemplary cartridge 9810 includes a formulation container 9854 including a formulation reservoir therein having a quantity of the injection formulation. A cartridge cap 9856 encloses the formulation container 9854. A cartridge discharge port 9858 extends from the formulation cartridge 9810. Optionally, in certain variations, the cartridge discharge port includes an opening feature configured to transition from a closed configuration to an open configuration. The opening feature includes, but is not limited to, a valve, membrane or the like that is opened prior to coupling with the chassis of the injection system.

[0076] In some embodiments, once the injection tool is inserted into the trunk or stem of the citrus plant, the injection tool may remain untouched and in place over multiple reinjections. In certain embodiments, the method further comprises: replacing the fluid delivery unit with a second fluid delivery unit; and delivering at least a portion of the injection formulation from the second fluid delivery unit through the injection tool into at least the active vasculature of the citrus plant. In some variations, the injection tool remains in the trunk or stem of the citrus plant over at least one growing season, at least two growing seasons, or at least three growing seasons.EXAMPLES

[0077] The presently disclosed subject matter will be better understood by reference to the following Examples, which are provided as exemplary of the invention, and not by way of limitation.Example 1: Field Trial

[0078] This example demonstrates the effect of a combination of oxytetracycline (OTC) and streptomycin (Strep) on treating citrus greening in orange trees.

[0079] Field trial design. A field trial was initiated on March 30 by applying treatments to commercial orange trees that have a Hamlin variety scion grafted onto an X639 variety rootstock. Treatments included the application of antibiotics using Invaio’s proprietary injection system into the scion of each tree. The trial was designed as a randomized complete block in which three treatments were applied to each of four trees within each of six replications at three different treatment dates. A full list of treatments is included in Table 1. OTC is a commercial oxytetracycline product and OTC (HC1) + Strep is a formulation made from technical grade oxytetracycline HC1 combined with streptomycin. All injections were made at a rate of 60 ml at the concentration shown in Table 1. One injection of antibiotics was made in each tree for the first two injections timings and two antibiotic injections were made per tree at the third application timing.Table 1.Treatment Concentration Injections per tree per date Treatment (mg / mL) application30-Mar OTC (HC1) + Strep 0.625 + 2.5 130-Mar OTC 1.58 130-Mar Nontreated n / a n / a15-Jun OTC (HC1) + Strep 0.625 + 2.5 115-Jun OTC 1.58 115-Jun Nontreated n / a n / a5-Oct OTC (HC1) + Strep 0.625 + 2.5 25-Oct OTC 1.58 25-Oct Nontreated n / a n / a

[0080] BRIX analysis. Fruit was collected from trees of each treatment by replication onDecember 8 and bulked according to treatment and replication to create 18 individual fruitsamples for BRIX analysis. On average, trees injected with OTC, or a combination of OTC (HC1) and Strep had higher BRIX a than nontreated trees (Table 2). The range in BRIX for nontreated trees across replications was 7.1 to 7.7 and the range in BRIX for OTC treated trees across replications was 7.6 to 8.4. The BRIX range across replications for OTC (HC1) + Strep treated trees was 7.6 to 8.0.Table 2.Treatment Replication BrixNontreated 1 7.7Nontreated 2 7.5Nontreated 3 7.4Nontreated 4 7.1Nontreated 5 7.5Nontreated 6 7.5Treatment average 7.5OTC (HC1) + Strep 1 7.6OTC (HC1) + Strep 2 8OTC (HC1) + Strep 3 7.9OTC (HC1) + Strep 4 7.6OTC (HC1) + Strep 5 7.9OTC (HC1) + Strep 6 7.6OTC 1 8.1OTC 2 8.4OTC 3 8.1OTC 4 8OTC 5 7.6OTC 6 7.6Treatment average 8.0

[0081] Fruit yield. Fruit yield was determined for trees of each treatment as the total weight (lbs) of fruit picked (harvested) from each tree on December 21. Fruit yield was recorded as an average by replication and as an average across all six replications (Table 3). The average fruit yield from each tree of each treatment was 48.7 lbs for the OTC treatment, 60.1 lbs for the OTC (HC1) + Strep treatment, and 32.0 lbs for the nontreated treatment. The range in average fruit yield across replications for nontreated trees was 23.1 to 45.2 lbs per tree and the range in average fruit yield across replications for OTC treated trees was 37.4 to 81.0 lbs per tree. The range in average fruit yield across replications for OTC (HC1) + Strep treated trees was 49.5 to 70.8 lbs per tree.Table 3.Treatment Replication Fruit yield (lbs per tree)OTC 1 43.7OTC 2 81.0OTC 3 41.6OTC 4 50.3OTC 5 37.4OTC 6 48.7Treatment average 50.4OTC (HC1) + Strep 1 52.2OTC (HC1) + Strep 2 70.8OTC (HC1) + Strep 3 60.5OTC (HC1) + Strep 4 66.6OTC (HC1) + Strep 5 61.2OTC (HC1) + Strep 6 49.5Treatment average 60.1Nontreated 1 27.4Nontreated 2 32.9Nontreated 3 45.2Nontreated 4 23.1Nontreated 5 28.1Nontreated 6 35.7Treatment average 32.0

[0082] Fruit drop. Fruit drop was determined for trees of each treatment as the number of fruit on the ground underneath each tree at each of six counting dates, approximately 2 weeks apart, beginning on October 13 and finishing prior to fruit harvest on December 21. Counted fruit were removed from the ground after each counting date. Fruit drop was recorded as an average by date and as an average across all six dates (Table 4). The average number of fruit dropped from trees of each treatment were 17.8 for the OTC treatment, 18.0 for the OTC (HC1) + Strep treatment, and 22.0 for the nontreated treatment. The range in average fruit drop across replications for nontreated trees was 20.5 to 25.3 and the range in average fruit drop across replications for OTC treated trees was 14.5 to 20.9. The range in average fruit drop across replications for OTC (HC1) + Strep treated trees was 13.3 to 21.1.Table 4.OTC (HC1)13- +OTC 1 Oct 14.3 Strep 1 13-Oct 11.8 Nontreated 1 13-Oct 18.8OTC OTC (HC1)28- +1 Oct 15.0 Strep 1 28-Oct 9.8 Nontreated 1 28-Oct 12.3OTC OTC9- (HC1) No +1 v 28.0 Strep 1 9-Nov 26.5 Nontreated 1 9-Nov 36.8OTC OTC24- (HC1) No +1 v 28.0 Strep 1 24-Nov 17.5 Nontreated 1 24-Nov 35.5OTC OTC8- (HC1) De +1 c 22.8 Strep 1 8-Dec 13.5 Nontreated 1 8-Dec 25.5OTC OTC21- (HC1) De +1 c 17.5 Strep 1 21-Dec 18.8 Nontreated 1 21-Dec 23.0Rep average across Rep average across dates 20.9 dates 16.3 Rep average across dates 25.3OTC OTC (HC1)13- +2 Oct 11.5 Strep 2 13-Oct 8.5 Nontreated 2 13-Oct 6.8OTC OTC (HC1)28- +2 Oct 14.5 Strep 2 28-Oct 10.8 Nontreated 2 28-Oct 15.5OTC OTC9- (HC1) No +2 v 31.5 Strep 2 9-Nov 28.3 Nontreated 2 9-Nov 29.5OTC OTC24- (HC1) No +2 v 26.8 Strep 2 24-Nov 21.5 Nontreated 2 24-Nov 21.8OTC OTC8- (HC1) De +2 c 19.0 Strep 2 8-Dec 23.5 Nontreated 2 8-Dec 23.3OTC OTC21- (HC1) De +2 c 20.0 Strep 2 21-Dec 25.3 Nontreated 2 21-Dec 26.8Rep average across Rep average across dates 20.5 dates 19.6 Rep average across dates 20.6SUBSTITUTE SHEET RULE 26OTC OTC (HC1)13- +3 Oct 8.8 Strep 3 13-Oct 8.3 Nontreated 3 13-Oct 11.0OTC OTC (HC1)28- +3 Oct 18.8 Strep 3 28-Oct 12.3 Nontreated 3 28-Oct 18.8OTC OTC9- (HC1) No +3 v 20.5 Strep 3 9-Nov 12.5 Nontreated 3 9-Nov 34.8OTC OTC24- (HC1) No +3 v 18.3 Strep 3 24-Nov 15.0 Nontreated 3 24-Nov 18.8OTC OTC8- (HC1) De +3 c 13.3 Strep 3 8-Dec 10.5 Nontreated 3 8-Dec 20.0OTC OTC21- (HC1) De +3 c 16.5 Strep 3 21-Dec 21.0 Nontreated 3 21-Dec 32.0Rep average across Rep average across dates 16.0 dates 13.3 Rep average across dates 22.5OTC OTC (HC1)13- +4 Oct 9.0 Strep 4 13-Oct 11.5 Nontreated 4 13-Oct 18.0OTC OTC (HC1)28- +4 Oct 18.3 Strep 4 28-Oct 18.3 Nontreated 4 28-Oct 24.0OTC OTC9- (HC1) No +4 v 23.8 Strep 4 9-Nov 28.3 Nontreated 4 9-Nov 29.8OTC OTC24- (HC1) No +4 v 20.8 Strep 4 24-Nov 24.8 Nontreated 4 24-Nov 29.0OTC OTC8- (HC1) De +4 c 14.0 Strep 4 8-Dec 19.5 Nontreated 4 8-Dec 13.5OTC OTC21- (HC1) De +4 c 16.8 Strep 4 21-Dec 24.3 Nontreated 4 21-Dec 18.0Rep average across Rep average across dates 17.1 dates 21.1 Rep average across dates 22.0OTC OTC (HC1)13- +5 Oct 7.3 Strep 5 13-Oct 11.5 Nontreated 5 13-Oct 12.5OTC OTC (HC1)28- +5 Oct 16.3 Strep 5 28-Oct 20.3 Nontreated 5 28-Oct 19.0SUBSTITUTE SHEET RULE 26OTC OTC9- (HC1) No +5 v 18.5 Strep 5 9-Nov 28.3 Nontreated 5 9-Nov 27.5OTC OTC24- (HC1) No +5 v 20.8 Strep 5 24-Nov 24.0 Nontreated 5 24-Nov 27.8OTC OTC8- (HC1) De +5 c 12.3 Strep 5 8-Dec 18.3 Nontreated 5 8-Dec 20.0OTC OTC21- (HC1) De +5 c 12.0 Strep 5 21-Dec 18.8 Nontreated 5 21-Dec 16.0Rep average across Rep average across dates 14.5 dates 20.2 Rep average across dates 20.5OTC OTC (HC1)13- +6 Oct 14.5 Strep 6 13-Oct 14.8 Nontreated 6 13-Oct 19.0OTC OTC (HC1)28- +6 Oct 19.8 Strep 6 28-Oct 16.5 Nontreated 6 28-Oct 20.8OTC OTC9- (HC1) No +6 v 22.0 Strep 6 9-Nov 25.8 Nontreated 6 9-Nov 29.8OTC OTC24- (HC1) No +6 v 21.8 Strep 6 24-Nov 15.0 Nontreated 6 24-Nov 27.5OTC OTC8- (HC1) De +6 c 15.0 Strep 6 8-Dec 18.0 Nontreated 6 8-Dec 15.5OTC OTC21- (HC1) De +6 c 15.0 Strep 6 21-Dec 16.3 Nontreated 6 21-Dec 18.3Rep average across Rep average across dates 18.0 dates 17.7 Rep average across dates 21.8Treatment average 17.8 Treatment average 18.0 Treatment average 22.1SUBSTITUTE SHEET RULE 26

[0083] Residue analysis. Fruit was collected from trees of each antibiotic treatment (OTC and OTC (HC1) + Strep) by replication on December 7 and bulked according to treatment and replication to create 12 individual fruit samples for OTC residue analysis. Similarly, fruit was collected from trees from two replications of nontreated treatments and bulked by replication to create 2 individual fruit samples for OTC residue analysis. No OTC residue was detected on fruit harvested from the nontreated trees. OTC residue detected in fruit bulked from trees treated with an antibiotic were all below the established minimum residue limit of 0.01 ppm. On average, trees injected with OTC had a residue detected of 0.007 ppm with a range of 0.002 ppm to 0.009 ppm across replications. Trees injected with OTC (HC1) + Strep had an average residue of 0.003 ppm with a range of 0 ppm to 0.008 ppm across replications (Table 5).Table 5.Treatment Replication Average Concentration (ppm)OTC 1 0.006666OTC 2 0.002633OTC 3 0.008066OTC 4 0.006366OTC 5 0.006533OTC 6 0.009433Treatment average 0.006616167OTC (HC1) + Strep 1 0OTC (HC1) + Strep 2 0OTC (HC1) + Strep 3 0.0035OTC (HC1) + Strep 4 0.0038OTC (HC1) + Strep 5 0.004233OTC (HC1) + Strep 6 0.0062Treatment average 0.0029555Nontreated 1 0Nontreated 2 0Treatment average 0

Claims

CLAIMSWhat is claimed is:

1. A method for controlling citrus greening in a citrus plant, wherein the citrus plant further has an active vasculature that runs through the trunk or stem to other parts of the citrus plant, the method comprising: injecting an injection formulation comprising a combination of (i) a tetracycline antibiotic or a salt thereof, and (ii) an aminoglycoside antibiotic or a salt thereof, into the active vasculature of the plant to control citrus greening in the citrus plant.

2. The method of claim 1, wherein the tetracycline antibiotic is oxy tetracycline.

3. The method of claim 1, wherein the aminoglycoside antibiotic is streptomycin.

4. The method of claim 1, wherein the active vasculature into which the injection formulation is injected is active vasculature in the trunk or stem of the citrus plant.

5. The method of claim 1 or 4, wherein the citrus plant is a citrus tree.

6. The method of any one of claims 1 to 5, wherein, after injection, the citrus plant has at least about 5%, at least about 10%, or at least about 15%, or between about 10% and about 25% reduced fruit drop as compared to an untreated citrus plant.

7. The method of any one of claims 1 to 6, wherein, after injection, the citrus plant produces fruit with at least about 1%, at least about 2%, at least about 3%, or at least about 4%, between about 3% and about 10% increased Brix as compared to an untreated citrus plant.

8. The method of any one of claims 1 to 7, wherein, after injection, the citrus plant has at least about 10%, at least about 20%, at least about 30%, at least about 40%, or at least about 50%, or between about 60% and about 95% increased fruit yield as compared to an untreated citrus plant.

9. The method of any one of claims 1 to 8, wherein the injecting of the injection formulation is performed using an injection system comprising an injection tool operatively connected to a fluid delivery unit, wherein the fluid delivery unit is configured to deliver the injection formulation.

10. The method of claim 9, wherein the injecting of the injection formulation comprises: piercing the trunk or stem of the citrus plant using the injection tool of the injection system; anddelivering at least a portion of the injection formulation from the fluid delivery unit through the injection tool into at least the active vasculature of the citrus plant.

11. The method of any one of claims 1 to 10, wherein the injection formulation is distributed throughout the trunk or stem and other parts of the citrus plant.

12. The method of claim 11, wherein the other parts of the citrus plant comprise fruits.

13. The method of claim 11 or 12, wherein the other parts of the citrus plant comprise leaves.

14. The method of any one of claims 9 to 13, wherein the fluid delivery unit is a spring- loaded fluid delivery unit.

15. The method of any one of claims 9 to 14, wherein the delivery unit comprises a pressurized formulation cartridge.

16. The method of any one of claims 9 to 15, further comprising: replacing the fluid delivery unit with a second fluid delivery unit; and delivering at least a portion of the injection formulation from the second fluid delivery unit through the injection tool into at least the active vasculature of the citrus plant.

17. The method of any one of claims 9 to 16, wherein the injection tool remains in the trunk or stem of the citrus plant over at least one growing season.

18. The method of any one of claims 9 to 17, wherein the injection tool remains in the trunk or stem of the citrus plant over multiple applications of the injection formulation.

19. The method of any one of claims 9 to 18, wherein the trunk of the citrus plant has bark, and the method further comprises: removing at least a portion of the bark prior to piercing the trunk.

20. The method of any one of claims 1 to 19, wherein the citrus plant is an orange tree.

21. The method of claim 20, wherein the orange tree to which the injection formulation is applied has fruit with an average oxytetracycline (OTC) residue of less than about 0.01 ppm.

22. The method of claim 20 or 21, wherein the method results in the orange tree to which the injection formulation is applied having an average fruit drop of less than about 20.

23. The method of any one of claims 20 to 22, wherein the method results in the orange tree to which the injection formulation is applied having an average fruit yield of at least about 50 lbs per plant, or between about 55 lbs and about 90 lbs per plant.

24. The method of any one of claims 20 to 23, wherein the method results in the orange tree to which the injection formulation is applied having an average Brix of at least about 7.5.

25. The method of any one of claims 20 to 24, wherein the method results in the orange tree to which the injection formulation is applied having fruit with an average decrease in fruitdrop by at least about 10% as compared to an orange tree to which the injection formulation has not been applied.

26. The method of any one of claims 20 to 25, wherein the method results in the orange tree to which the injection formulation is applied having fruit with an average increase in Brix by at least about 4% as compared to an orange tree to which the injection formulation has not been applied.

27. The method of any one of claims 20 to 26, wherein the method results in the orange tree to which the injection formulation is applied having fruit with an average increase in fruit yield by at least about 10% as compared to an orange tree to which the injection formulation has not been applied.

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