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Citrus crops are threatened due to
Antibiotics in Your Orange Juice?
A bacterial disease thought to have originated in China in the early 1900s has grown to become one of the most destructive plant diseases worldwide affecting citrus trees. It was first found in Florida in 2005 and has since been found in at least seven states in the US causing substantial losses in an over $9 billion industry.
Citrus greening, also called Huanglongbing (HLB) or yellow dragon disease, is caused by Candidatus liberocacter asiaticus, a non-culturable Gram-negative bacteria that is transmitted by a host- specific type of jumping plant lice called the Asian citrus psyllid (ACP). These organisms can reproduce asexually with the females laying up to 800 eggs annually.
The infection prevents the citrus from ripening which renders crops useless and ultimately destroys infected trees. Methods of treatment include using heat, antibiotics, biological controls, and genetic modification. Without the use of one or more of these methods, farmers are often left with no choice other than to use insecticides and cut down infected trees, which often proves to be ineffective at stopping the spread of the disease.
Genetically modified trees confer resistance against the disease, Using a combination of heat and antibiotics also works well to stop or slow the spread, but these options are often unfavorable with consumers. In addition, the detrimental effect of broad-spectrum antibiotic treatments on plant-beneficial microbiota and the potential implications on public and ecosystem health remains a concern. Nonetheless, these treatments have been found to be effective in the recovery or slowing of disease progression on infected trees.
Most of the studies using tetracyclines and similar bactericides were conducted in the 1960s through the 1980s where several members of the tetracycline group were investigated, including tetracycline hydrochloride, chlortetracycline, dimethyl chlortetracycline, and oxytetracycline. For the most part, these studies investigated the performance of antibiotics when applied by foliar application or by trunk injection. Some of the tetracyclines used in these experiments were found to be toxic to the plant, causing symptoms such as yellowing, smaller leaves, and discoloration at trunk injection sites. When tested, dimethyl chlortetracycline and oxytetracycline did not cause the same symptoms, possibly because of the greater solubility of these agents. In addition, the pH in these formulations could be adjusted to prevent toxicity to plants. Due to earlier toxicity issues, oxytetracycline was not widely used, but recently the industry has taken a renewed interest due to studies showing its efficacy. Results from these studies, in addition to other independent studies, led to a 2015 petition to the EPA for a Section 18 emergency exemption that would allow the use of these agents on citrus in Florida. The Florida Department of Agriculture asserted that an emergency situation existed in accordance with the criteria for approval of an emergency exemption and requested the use of two oxytetracycline products on citrus crops. This new regulation establishes a time-limited tolerance for residues of oxytetracycline, oxytetracycline calcium, and oxytetracycline hydrochloride. These formulations are registered as pesticides and are considered to be of equal toxicity and referred to equally as oxytetracycline.
The EPA concluded that this time-limited tolerance expires on December 31, 2019, and that the residues are safe (based upon toxicological data) as long as they do not exceed the authorized level. It is also stated that the EPA would act to revoke the time-limited tolerance earlier if any additional scientific data or other relevant data showed a change in safety status. This is still a relatively new development, and it remains to be seen if any downstream effects may occur due to this regulation. Probably one of the biggest concerns is the promotion of antibiotic resistance if overused. It may be worth noting that other approaches, such as releasing parasitic wasps in affected areas of California, have been employed and may be equally effective as a way of eradicating or controlling ACP.
By Marcus Zuzow
Plazomicin now available!
Disks Now Available from Hardy
- Plazomicin, “Zemdri” (Z9331)
- Ceftazidime/Avibactam, “Avycaz” (Z9351, Z9355)
- Ceftolozane/Tazobactam, “Zerbaxa” (Z9341, Z9345)
- Delafloxacin, “Baxdela” (Z9301, Z9305)
- Meropenem/Vaborbactam, “Vabomere” (Z9321, Z9325)
- Are compatible with all BD Disk dispensers.
- Feature “last disk recognition” so you know when a refill is needed.
- Include all traditional and newer antibiotics.
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Carrot Broth One-Step
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- Detects hemolytic Group B Strep from the initial broth culture
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- Found to be 100% sensitive and up to 100% specific in a recent study
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“Throw your hat into the ring”
This expression came from the days when a boxing match was held in an outdoor area marked off in a circle (ring). If any young man was bold enough and wanted to challenge the winner, he would throw his hat into the ring, since his voice could not be heard amongst the hubbub of the crowd. The first time this expression made it into print was in 1805.
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Think about it…
- Did you ever notice that when you blow in a dog’s face, he gets mad at you, but when you take him for a car ride, he sticks his head out the window?
- Why do we press harder on a remote control when we know the batteries are going dead?
- Why do banks charge a fee on ‘insufficient funds’ when they know there is not enough money?
- Why does someone believe you when you say there are four billion stars, but check when you say the paint is wet?
- Why do they use sterilized needles for death by lethal injection?
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Wisdom to Ponder…
1856 ~ 1943
Born in Serbia, this American inventor developed the first alternating current (AC) system; also he was among the first to work on X-ray machines, wireless lighting and controls, and ozone generators.
“The scientists of today think deeply instead of clearly. One must be sane to think clearly, but one can think deeply and be quite insane.”
“The feeling is constantly growing on me that I had been the first to hear the greeting of one planet to another.”
“I myself eschew all stimulants. I also practically abstain from meat.”
“In the twenty-first century, the robot will take the place which slave labor occupied in ancient civilization.”
“Our senses enable us to perceive only a minute portion of the outside world.”
“Let the future tell the truth, and evaluate each one according to his work and accomplishments. The present is theirs; the future, for which I have really worked, is mine.”
“Be alone, that is the secret of invention; be alone, that is when ideas are born.”
“The gift of mental poser comes from God, Divine Being, and if we concentrate our minds on that truth, we become in tune with this great power.
“Fights between individuals, as well as governments and nations, invariably result from misunderstandings in the broadest interpretation of this term. Misunderstandings are always caused by the inability of appreciating one another’s point of view.”
“We are whirling through endless space, with and inconceivable speed, all around everything is spinning, everything is moving, and everywhere there is energy. There must be some way of availing ourselves of this energy more directly. Then, with the light obtained from the medium, with the power derived from it, with every form of energy obtained without effort, from the store forever inexhaustible, humanity will advance with giant strides. The mere contemplation of these magnificent possibilities expand our minds, strengthens our hopes and and fills our hearts with supreme delight.”
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