criteria for selecting a good arborist?

Does anyone have any recommendations on how to select a good arborist?

We would like to get a second opinion/diagnosis on our Robinia pseudocarpus 'Purple Robe' trees. Our HOA landscaping company says they need to be replaced. The homeowners who live near these trees question whether that is true or whether they can be preserved.

The trees in the center of this photograph are ones in question.

Thanks in advance for you input.

Below is a link to the California Arborists Association

http://www.cal-arb-association.com/

For solid university research based horticultural information contact your local University Of California Cooperative Extension Master Gardener office located in San Jose at 408-282-3105. You can ask about your trees and their condition and they will provide you answers based on scientific research. Sometimes, here in Ohio, the Extension Agent will make a site visit. I can't promise you that will happen for you however. I'm a Master Gardener here and I know how the program works here. It's a terrific free source of up to the minute scientifically backed garden information.

http://www.mastergardeners.org/scc.html

One more thing. Do you know what the problem might be? I can't find Robinia pseudocarpus. I can find Robinia pseudoacacia 'Purple Robe.' This species is not listed for your zone - only to zone 8.

http://hort.ufl.edu/trees/ROBPSEC.pdf

This message was edited Oct 29, 2008 12:58 PM

It does perfectly well in zone 9, though.

Resin

I was conservative in the zone recommendation as Dirr gives it a 8(9) qualification and the US Forest Service goes to 8 only. Could it be heat as not all zone 9's experience the same high temps?

Yep, it might not do so well in the heat/humidity of zone 9 Florida.

Resin

After looking at climate data for Sunnyvale CA, however, summer heat would not be an issue. The climate there is very mild. And enviable I might add. Your first observation was correct Resin. It should do fine in garden_mermaid's climate.

Thanks all!

I meant to type 'pseudoacacia'. This is a purple robe tree that does very well in our climate. The water district recommends this as a low water using tree. Ours have been overwatered, resulting in some suckering. We had one tree blow over, which I really think may be due to a combination of too shallow of a planting hole in '97 (I watched them being planted) and the frequent shallow watering.

I'd like to find out if we can possibly salvage the remaining trees and encourage deep rooting by changing the irrigation practices, and perhaps some temporary bracing if needed. I see these trees planted near lawns in other places around town, and they are not having the same problem as ours. I'm hoping these can be saved at a reasonable cost, versus replacing them.

I will call the arborist's association for suggestions.

Please give your Cooperative Extension agent a call too.

So what happened to your trees?

I would guess that the reason they wanted to remove them is to prevent any damage to the buildings. The problem with purple robes is the weak branching structure. They tend to fork and branch at very steep angles which become weaker as the tree grows and there is more weight on the branches. The tree in the middle has a very narrow fork about 1/3 of the way up which may cause one or both of those tops to split off in high winds. The split can rip the whole tree apart. Willows, Lombardy poplar, and Bradford pear can have the same problems and they just get worse with age. Bracing structures can help for a while but the tree will eventually fall apart.

The other problem might be that they are planted too close together. Those trees are still relatively young but their crowns are already touching and shading each others lower branches.

The trees are still here, thankfully. We had fierce windstorms over the Christmas holiday and the locust tree are doing just fine. A group of homeowners hired an independent arborist (indepedent of our landscape company) to do a hazard analysis of the locust trees. It turns out these are Idaho locust on black locust root stock. The bark splitting is their normal growth pattern (not a structural weakness) and the splits fill in with time to make a vertical stripe pattern on the trunks.

The independent hazard analysis pointed out that the branches with sharp angles were the weak spots and that proper structural pruning should have been done within the first 3 years of planting the trees. Still, the overall assessment was that the locust trees were not a hazard. The tree that blew over at the beginning of last summer suffered from root girdling, which was determined to be the cause of the fall. This was a condition that could have been corrected a few years ago. The ornamental pears in the courtyard were determined to be a immediate hazard. We had some weight reduction of those limbs.

The Board agreed to have a discussion between the two arborists at our January 7th HOA meeting. Unfortunately our arborist has been called out of town and now won't be able to make that meeting. I did send my write up of the hazard analysis to the HOA Board and am prepared to discuss it with the landscape company's arborist at our next meeting if we are not able to reschedule the topic. Hopefull we can some up with a plan that works for all.

Sadly, most trees in landscaping projects are basically ignored after planting unless something is really wrong with them.

The building I work in now was built five years ago and when I got here last year the trees were being strangled by the support wires that had never been removed. One of the maples (which is planted ina really bad place for a maple) had actually completely around the wire so they had to just cut the ends and leave it in the tree.

When I am walking through our neighborhood I sometimes want to carry a pair of wire cutters to free the poor, abused trees in people's front yards. Most people never seem to notice that their trees are living things that need care and training to reach their full potential.

I know you love your trees, but you may want to consider a phased replacement program that removes one or two problem trees at a time and replaces them with trees that will do better in the long run with less care. In your climate there are a number of very interesting trees you could replace them with. A diverse selection of trees will also reduce the chances of several trees having the same problem at the same time.

We are facing that problem around our capital buildings right now. About 75% of the trees are siberian elms and they are threatened by dutch elm disease. The public is opposed to removing any trees but if the trees get infected we could lose them all within a year or two. Then the capital grounds would look really awful. I would like to have a lot of different trees like the arboretum near the capital in Sacramento.

Good luck!

Do they really have Siberian Elms growing there at the capitol too? I hope not. I know there are American Elms there.

Thanks Katlian. Those of us who enjoy this courtyard have no problem with a phased replacement if that is what is needed. We just want to ensure that whatever trees are selected will grow tall and provide a similar effect. We also don't need the added expense of replacing trees at this point in time. I'm hoping to convince the Board that we need to have an arborist inspect all our trees at least once a year, (preferably twice a year in fall and spring) and have a long term maintenance plan established. We seem to be operating under crisis management where the arborists are only called upon when there is a problem.

Some of the elms planted around the capitol building are American but most the trees on the rest of campus are the weedy Siberian elms. Most of the older parts of town have Siberian elms and the seedlings crop up everywhere. I have spent many hours cussing out elm seedlings as I dig them out of the yard. I swear they have five times more root than shoot.

Sadly, it seems like everything is crisis management, I'm not sure if that's an american thing or just a human trait. Very few people I know act with the long-term in mind. I know I have been guilty of that when I'm buying plants. It's usually "Ooh, that's pretty" without considering where I'm going to have room for it.