Active Member
Watchung, NJ
I treated a number of trees last fall that I thought were going to die. Some of them from construction, others just poor vigor. I've been checking on them recently and they all look amazing. Maybe its not snake oil afterall.


Well-Known Member
We have had lots of success with Cambistat in many situations and for many species of tree. Watch out though, even though it is labelled to work for Dogwoods, we have had several instances where the trees have exhibited major problems after treatment. Small leaves you can live with, completely dead trees are kind of hard to explain away.


Well-Known Member
Cheers to Tom Prosser and all at Rainbow Scientific for not only keeping up with Treebuzz, but more importantly caring about their clients.

Even though it was more than likely my fault for not paying attention to the updated lists for recommended use for Cambistat, they (Rainbow Scientific) offered to help with compensation for my clients dead Dogwoods.

I stressed in my original post on Cambistat that my company has had terrific results with the product, well now we have also had terrific results with the company that makes the product. I thought this type of customer service was extinct.

I have no intention of pressing Rainbow Scientific for compensation. As far as I am concerned they have more than proven their dedication to my companies well being and to my clients trees. Consider this a resounding recommendation for using Rainbow Scientific products.



New Member
IMO these growth regulators, especially paclobutrazol (PBZ) are going to be the next big wave in arboriculture. It is my understanding the labels/formulations will be changed soon for a variety of uses from construction inury, drought relief, transplant shock, and even fungicide use.

Thanks for starting this thread. It's important we keep sharing our observations and providing feedback to the distributors/manufacturers. We are a small enough industry that "they" are still receptive to our comments.

Everytime I'm involved in helping to organize a workshop I always recommend we invite a researcher or distributor of growth regulators (especially PBZ) to speak.


Active Member
In the years since Sci Vance has introduced the product, they have altered the doses on many species based on feedback from the field. Rich H, that sounds like a bad experience. I've learned to be careful and err on the side of "less is more" with growth regulators until I see with me own little eyes how it affects different trees in different situations.
Has anyone noticed excessive dead wood production after treatment with plant growth regulators?


New Member
Grand Marais, MN
Well, being a Guinea pig is part of the economic reality.

And it is appreciative that Rainbow (label rights, not manufacturer) is willing to go the distance.

But it's also an intersting reality that we're concerned with adapting the tree to the client instead of the other way around. Is there something available that'll keep a puppy a puppy, or a toddler more like a pet kid forever?

Just making a splat against wholesale civilization, I'll be grounded later today, taking a giant out from over a new house where they changed their mind about the big beautiful shade tree that inspired them to build there in the first place. Sorry.


Active Member
Watchung, NJ
no excessive deadwood, actually only positive results from big trees in a state of distress. Usually we treat trees suffering from construction damage, but we treated a landmark White Oak (drought stress) that was just old and tired and it responded beautifully.

On the other hand, we treated a fastigiated(sp?) Hornbeam on a front foundation to keep its growth in check and every shrub under it died. The tree looks great though and has only grown 2" this year. Pain vs. pleasure? Also, be careful with Japanese Maple, they don't like the stuff.

Here's my bottom line.... I tell a customer with a failing tree to allow me to open up my toolbox in an attempt to fix it. I HAVE Cambistat in that toolbox, as well as other things(i.e. air spade etc...). I let them know before hand that if the trees vascular system is so far spanked as to not allow my treatments to translocate, it won't work!! Usually they are willing to take the chance and do everything to save the tree. Keep in mind that you want to totally undersell it. Not for lack of confidence in the product, but for lack of total knowledge of the trees condition. It's not snakeoil.

I'm not pitching the company, but you may want to reach out to them. They are extremely helpful as well as insightful.



New Member
Minnetrista MN
We estimate now that over 300,000 trees have been treated with Cambistat since it came out in 2002. This has given us a large number of trees to analyze and refine the process.

I want to respond to Roxy and his comment to go light. We have updated the rate chart 7 times now and beleive that you should follow the rate chart EXACTLY. Reduce dosage as instructed in the application guide. The rates have been refined very thoroughly. The goal has been to create an application guide and system that has minimal chance of too much growth reduction.

I believe the 4 best uses for this material are:
1. Managing the growth on large trees growing on smaller sites (To keep from outgrowing the soil volume available to support it)

2. To increase the fibrous root systems of yard trees that are stressed from drought or other situations.

3. To increase the trees ability to manage its water better in situations where it is prone to drought.

4. To increase tolerance to leaf fungus diseases.

Companies such as Bartlett, Davey and The Care of Trees have made it a staple in their tree health programs, which bodes well for its future. Please continue to call us with feedback.
Tom Prosser
Rainbow Treecare Scientific


Tom, I may have talked to you or someone else there about this... Have you guys developed the rate charts mostly from trees up there in Minnesota? What have you found about differing rates in different latitudes and habitats (as much as you can tell these things).
One other thing we run into alot around here are really really old, relatively small trees on ridges or certain soils that are already growing incredibly slowly, and suddenly have severe root damage from new home construction. For example, last week I looked at a chestnut oak that is absolutely over 200 years old, most likely over 300, really; the trunk is about 30 inches and it just lost about 30-40 percent of the roots on one side. What would a GR do to such a slow-growing tree?
Venice, FL
We have used Cambistat with success in the past. However, we are going to give Mastiff a try in the next couple weeks on several live oaks. I don't know the exact chemical comparison between paclobutrazol and flurprimidol. We have seen more scientific data on Cambistat (which I appreciate..Tree guys are not stupid and can handle big words and concepts.) but I like that Mastiff is a direct inject chemical. It's not applied by basal drench or soil injection. Can anyone shed light on the pros/cons of the 2??


New Member
Denver, Colorado
I like that Mastiff is a direct inject chemical. It's not applied by basal drench or soil injection. Can anyone shed light on the pros/cons of the 2??

[/ QUOTE ]

The trunk injection is invasive and causes a wound where as the basal drench does not. How much of a wound is created by trunk injection is unclear. It seems everyone has an opinion but there is a lack of scientific research data. There is also the equipment cost difference between an injection system and the basal drench. For Cambistat the basal drench has worked well for me.

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