What are PGRs in Hydroponics?

Plant Growth Regulators (PGRs), also described as nutrients, growth boosters, bloom boosters, vitamins, hormones and bloom enhancers, fall under the definition of an agricultural chemical product, commonly termed pesticides. They are substances that modify the physiology of plants to alter their natural development. Plant hormones found in PGRs are not nutrients but chemicals that modify the physiology of the plant to change how it grows.

Brands that you may be familiar with that are Product Growth Regulators commonly found on the shelf in Australian hydroponic stores include CYCO (A), CYCO (B), Bonza Bud, Rock Juice, Superbud, Yield Masta, Sudden Impact and U-Turn. Brands found in other countries include Phosphoload (Superbud rebranded, North America), Flower Dragon (North America), Gravity (North America), Bushmaster (North America), Boonta Bud (UK), Rox (UK), Mega Bud (North America) and Dr Nodes (renamed Mr No - North America).

The Poisons Standard 2010 published by the Australian Government under the Therapeutic Goods Act 1989 has defined the term of pesticide as any substance or mixture of substances used or intended to be used:

  • (a)
    for preventing, destroying, repelling, attracting, inhibiting or controlling any insects, rodents, birds, nematodes, bacteria, fungi, weeds or other forms of plant or animal life or viruses, which are pests; or
  • (b)
    as a plant regulator, promoter, defoliant or desiccant for food storage, household, industrial, commercial, agricultural and non-agricultural application, but does not include veterinary drugs, stock medicines, stock feeds, stock feed additives, drugs for human use, food additives or fertilisers

Such chemicals are designed to be toxic to living organisms, so it should not be surprising that they have been linked with a range of adverse health effects, including cancer, neurological, 1 respiratory and dermatological diseases.2

There are over 40 toxic chemicals that can be found in PGRs; Daminozide is one of them. It's the common ingredient found in the majority of popular hydroponic Plant Growth Regulators. In 1989 it was withdrawn by the manufacturer after the U.S. Environmental Protection Agency proposed banning it based on unacceptably high cancer risks to consumers.3 Also in 1989, it became illegal to use Daminozide on food crops in the US.4

“Chlormequat Chloride is a pesticide that is toxic to wildlife.5
The suicide of a young man is reported with the plant growth
regulator Cycocel (chlorocholine chloride and choline chloride).6

Say No to PGRs in hydroponics.

Other disturbing facts on agricultural chemicals that are contained in some PGRs are:

Chlormequat Chloride is a pesticide that is toxic to wildlife.5 The suicide of a young man is reported with the plant growth regulator Cycocel (chlorocholine chloride and choline chloride).6 In Denmark, results from experiments with pigs in the late 1980’s showed sows that display impaired reproduction. 7

Daminozide (Alar) is perhaps one of the most controversial agrochemicals ever, eclipsed only by Agent Orange, after the "Alar scare" in 1989 in which a CBS 60 Minutes USA show labeled Alar "a potent human carcinogen", resulting in the near bankruptcy of the US apple industry. The use of Daminozide in any consumable crop is, therefore, illegal. The dangers it poses when used to grow a short-term deciduous crop, which is then ingested via inhalation, are unknown (medicinal herb consumers being the lab rats of hydroponic manufacturers who falsely market Daminozide as "phytominerals", "citrates", "tartarates", "arginates" and "rare earth elements").

Paclobutrazol is classed as a herbicide/pesticide PGR. Paclobutrazol is an S5 poison. Its use is prohibited in many EU countries. The WHO lists Paclobutrazol as "Moderately Hazardous". Paclobutrazol has been shown to be an environmental contaminant (Kathrin Reintjes et al 2006). In field situations, Paclobutrazol is shown to have a half-life ranging from 3 to 12 months (Lever 1986) or 12 to 18 months, although some have reported persistence as long as 3 years (Jacyna and Dodds, 1995). Some commercial greenhouse operations have had issues dealing with chemical residues.15

Acetic Acid in the pure acid and its concentrated solutions are dangerously corrosive, used in the production of soft drink bottles; photographic film; wood glue, as well as synthetic fibres and fabrics.

Naphthalene is the primary ingredient of mothballs. It is volatile, forming a flammable vapour, and readily sublimes at room temperature.8

Ammonium Phosphate is used as a flame retardant in thermoplastic compositions.9

Cyanamide has a modest toxicity in humans. 10

Auxin is a member of the family indole-3-acetic acid (IAA) the most potent native Auxin. Molecules of IAA are chemically labile in aqueous solution, so IAA is not used commercially as a plant growth regulator.

Methylated Spirits is used as a fuel for marine and ultra-light camping (backpacking) stoves, as a sanding aid 11, as a mealy bug exterminator 12, a cleaning aid in removing ink stains from upholstery or clothes, a solvent in shellac and shellac-based products, as a germicide in the removal of fungus from skin and cold sore treatment.

Imidacloprid. A study on rats indicated that the thyroid is the organ most affected by Imidacloprid.13

2,4-D is the powerful defoliant and herbicide Agent Orange, used extensively throughout the Vietnam War, contained 2,4-D. 14

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