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Messenger - A Plant Health Activator

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Eden Bioscience, the company that originally marketed Messenger has sold the rights to the product. Since then the results and reporting do not seem to have warranted continued interest in the harpin products. I guess it seemed too good to be true.


There aren’t many tools a gardener can use to be pro-active in the fight against diseases. Plant health activator, Messenger, shows great promise in helping to grow better plants and in cutting down on the need for fertilizers and pesticides.

It’s too early to say with absolute certainty, Messenger is a wonder tonic for plants, but researchers are cautiously optimistic. It is endorsed by gardening associations, including the American Rose Society, and is available in most garden centers.


  • Plants treated with Messenger are less prone to disease and when attacked, recover faster.
  • Messenger can protect plants from all sorts of pathogens: fungal, bacterial and even viral.
  • It is not genetic or systemic.
  • Non-toxic and breaks down quickly
  • So environmentally benign it is labeled for use on aquatic plants, on or above the water line.


  • Mesenger hasn’t been around long enough to be absolutely certain of its effects
  • Different plants respond to different degrees
  • Must be reapplied every 3 weeks


  • Messenger is not a pesticide, fertilizer or a pathogen and does not hurt the plant.
  • It fools the plant into thinking it's being attacked by disease and triggers its immune defenses.
  • It is environmentally safe, breaking down quickly. Does not pollute ground or surface water.
  • Promotes root growth, vigor, disease and stress resistence, increased flowering and fruit set.
  • Works especially well on roses, even extending the vase life of cut flowers.
  • Labeling now includes use on aquatic plants that either float or grow above the water line.
  • Messenger Seed Treatment brings the influence of harpin proteins into play before germination.
  • Similar products are marketed, but only Messenger uses the plant's own processes to protect it.
  • Messenger can be used on all types of plants, indoors and out, including lawn, trees and shrubs.
  • Messenger is not a one time shot and will need to be reapplied.

Guide Review - Messenger - A Plant Health Activator

Messenger®, marketed as a plant health activator, is a discovery that was almost stumbled on by accident. Researchers at Cornell University were studying fire blight in apples and pears when they discovered that the harpin proteins being produced as a kind of by-product of the disease, were triggering an early warning mechanism in the plant being attacked, causing it to activate its own defense responses. Messenger is a topical application of harpin protein that produces the same effect in plants. However Messenger is not a pathogen and does not hurt the plant. The plant doesn’t realize it is not being attacked, it just senses harpin proteins and is tricked into responding. The response is 3-fold:

  1. The immune response genes are spurred into action

  2. A growth response is triggered and the plant begins photosynthesizing at a higher level

  3. The reproductive inclination is revved and the plant begins producing more blossoms

According to Jeff McClellan, a Market Manager for Home and Garden at EDEN Bioscience , none of these reactions appear detrimental to the plant. Messenger is applied to the surface of the plant. It is not genetic or systemic. Messenger is non-toxic and breaks down quickly. In fact, since it is a protein, it is a food source.

Messenger is labeled as a bio-pesticide, but Eden Bioscience prefers to refer to it as a Plant Health Regulator. Treated plants will be less disease prone and better able to withstand disease and stress.

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