There is a lenghty discussion, still on page 1, about Messenger on the Botany Forum. We have much to learn about this new product. At this point commercial growers should be experimenting and reporting results using Messenger. A few have. The developer/patent holder is not releasing a lot of helpful information yet. Over time the growers who post here will figure it out.

Messenger is based on a naturally occurring protein, harpin (actually derived from the pathogen that produces fireblight), that was discovered and initially tested by Cornell University. The concept is that the application of this protein triggers a response in plants that activates their existing immune system. While it does not necessarily result in faster or better growth, it does often encourage healthier growth and more disease resistance. It does not work equally well on all plants.

Scientific testing is currently underway to determine exactly what benefits this product may generate but to assume that applications will result in rapid and lush growth is misleading. Better root development and increased cropping has been noted in some cases, but these may be only isolated side effects. The intent of the product is to bolster the plant's immune system and increase disease resistance.

Messenger is marketed and distributed by Eden Bioscience, a local biotechnology company. Searches under the key words "harpin", "Messenger" or "Eden Bioscience" should turn up considerable information.

For more on harpin...

Here is a link that might be useful: The Myth of the Magic Bullet

Plants don't have immune systems.

You might want to brush up on your botany. While plants don't have immune systems that function in the same manner as that of humans or other vertebrates, they most certainly do have genetic, metabolic and chemical defense systems that protect them from pathogens. And complicated enough to keep scores of universities, bioscientists and genetic engineers busy studying them and exactly how they work and how they may be synthesized or otherwise stimulated to increase disease and pest resistance.

I think Sue may know a little about botany already.

Here is a link that might be useful: Oberle Botanical - About Us

Ron and Sue,
I am on the fence in this situation. As I said above, growers will test and trial harpin products and report their observations. Three years ago when news broke that it might be possible to stimulate a plant's immune system so that it would continue to grow and produce after an insect/disease onslaught I began researching. Frankly, my first thoughts agreed with Sue's. "Plants don't have immune systems." At the moment I am in my third year of experimenting; a summer which so far has been intense heat coupled with daily monsoon rains. Perfect for disease and related problems. One of my experiments is working so far. I thought it might have potential and asked a retired horticulturist in town to try the experiment this summer. Due to recent surgery I have not been near his garden however he is giving me very positive reports by telephone. Time will tell. If I feel there is merit in the idea I will just post it here for all of you to experiment with next spring. It only costs pennies per gallon and is easy to make. The bottom line of my thinking at the moment is that it may be possible to "stimulate" (if that is the proper terminology) the "immune" (proper terminology?) of some plants. My experiments have been with edible plants only. I have not trialed Messenger or related products, yet. Bottom line....my mind is not closed on the subject. I think I know the next organic step in this type of research but do not have the facilities to conduct such experiments. There is a well-known research facility not too far away and I plan to knock on the door soon to see if anyone is interested in testing my theories.

A syndicated radio program host on gardening had recommended Messenger so I thought I might try it. I've srpayed it three times so far at 20 day intervals on my greenhouse tomato and cucumber crops and I don't have a control for a research report but I think the tomatoes and cucs respond to the spray. I do think blossom numbers are higher and I've never had branches (& suckers) on tomatoes that were as thick as they are this year with a same variety. I have noticed more irregularity in tomato size with my first few pickings, some fruit are huge wile a much larger number have been smaller than normal. I repeat that all these observations may not be as a result of the messenger.

No controls, no basis for comparison. Maybe the weather was better for them this year, or you did something else different that appeared to give better results. You really have to include a control group to make sure something else isn't going on, that is making them all grow better, as well as a method for systematically quantifying the response, to come up with anything useful.

yawn.....what was the discussion again? Harpin? Messenger? Its a magic potion that only works when it wants to. Used it, provided a controlled block of soft tissue perennials, and I saw no improvement toward disease and viral infection. Personally, I go towards helping the root system first, and that is where PlantShield and products alike come into play.