Long story: A very important client, with close family ties to the New York Botanical Garden, lost an Acer japonicum 'Vitifolium' suddenly last year (2009). I would like to plant another Acer sp. to make this important client happy, and because a Magnolia sp. is just not as effective in this Japanese inspired gravel garden. I planted the Acer the summer before it’s demise (2008, timing due to new construction on the residence) as a severely pot-bound specimen. I did what I could to loosen the root ball, checked for severely girdling roots, added compost and bark, planted it high, gave it tons of water, requested that additional irrigation be installed.... and held my breath. The large leaves suffered that year, displaying some necrosis between the veins near the petiole, and also around the edges. I believed this was possibly due to it's new exposure... now in full sun, and transplant stress. By the end of the summer, new growth was displaying deep within the canopy, near the the trunk. (I thought that confirmed my exposure analysis.) The next spring (2009), leaves expanded looking great! Within a month, we lost one branch, then two more, and then most of the canopy. Distressed, I called the arborist for a post-mortem. He diagnosed it as severe root girdling, deep within the root ball, and blamed poor growing practices by some growers on the west coast. I confirmed this with friends and instructors at the NYBG. (The arborist now has the roots and flare of the dead Acer, which he has cleaned and uses as a poster child for internal girdling.) He also decided to send a tissue sample for testing because the pattern of branch loss indicated verticillium wilt, although there was no black in the cambium. The pathology tests came back positive, and we were told we couldn’t plant another Acer in it’s place, and to keep an eye on the other A.j. ‘Aconitifolium’ twenty-five feet away. My research led me to this forum, where I read that the disease can be transferred from parent to offspring, although I’m not clear if this is only through the scion, and I don’t know if A.j. ‘Vitifolium’ is grafted. That lead me to ask a soil microbiologist if a test existed to determine if the verticillium pathogen was in the soil… apparently it can’t be done because isolation of just one pathogen in any soil would be impossible. Which leads me to my question. Is it possible that the verticillium wilt is not in the soil, that root girdling alone killed the tree, and that the positive results of the tissue test was because the disease is inherent in these trees? Look forward to you responses… and questions.
Hello Paige, Thank you for the careful description. 'Vitifolium' is grafted, and it is possible that verticillium was passed in the scion wood. In the case of this particular cultivar however there is often a confusion between large leaved species specimens and the "true" clone. Regardless my guess is that in your case verticillium was present but not the leading cause of death and as you suspect poor culture killed the tree. (Poor before you got it, sounds as if you did all the right things). It is a matter of some controversy as to whether another acer can be planted in the place. My opinion is yes if the tree was sick before it was planted, which seems to be the case. I have successfully replaced palmatums under these circumstances. Others disagree, and of course ultimately the choice is whether to risk another large and expensive tree in the spot. (Hopefully a better specimen this time.) I'm surprised there is no test that can determine dangerous levels of V. dahliae or albo-atrum in the soil. This would be the best measure of the wisdom of proceeding with another acer. HTH -E[FONT=Arial, Helvetica, sans-serif][/FONT][FONT=Arial, Helvetica, sans-serif][/FONT]
Thank you for your quick and encouraging response, Emery! Is it rude to ask what your credentials are?
An interesting and unusual question anyway. I am an amateur not a nurseryman or botanist. I have what most people consider a large maple collection, (though some here might consider a medium-sized one), with no particular emphasis on japonicum or palmatum cultivars. I suppose it is often the case that credentials come with experience. I am starting to have a little bit of that, though I am happy that there is always much to learn about these plants. Certainly I've seen many maples with verticillium that lived (I currently own several) and many root bound specimens. I think you will find that most on this forum are of my ilk with more or less experience, some professionals but not necessarily with more knowledge than the amateurs. In terms of professional advice, you don't always get what you pay for. (Of course in this case the advice hasn't cost much either!) Good luck, -E
Experience trumps education, especially when it comes to horticulture, I certainly didn't mean to offend. You have encouraged me to entertain the idea of another Acer. Thank you. Please accept my sincerest apology for giving the impression that I'm not appreciative of your help. I'll let you know the outcome. Best, Paige
Emery, The more you learn about soil microbiology the less you would be surprised by the lack of testing capabilities, it is darn complex down there. I am not saying it is impossible but that it is not simple and, thus, readily available. From what I have read on the subject I am convinced that the verticillium fungi are present in all soils. What changes, as you correctly point out, is the relative levels vs. other fungi. It is well known that soils that have been used for cultivation of solanaceaes have a high proliferation of verticillium fungi which make those soils inhospitable for most maples. This is the case for large parts of Northern France and Belgium. Even though my garden is in pristine forest land, I always have a few maples that are affected by verticillium each year. Some die and some recover. My approach is to optimize growing conditions to make the trees as healthy as possible and let the micro organisms fight each other ‘down there’. When a maple in the ground dies of verticillium, I remove the maple with a decent sized root ball and replant another maple in the same place. I know this goes against conventional wisdom but, so far, I do not regret it. Gomero
Last year I added some super-good quality, most excellent garden soil to my potting mix for container maples .........the bed I took the soil from had most recently been used for growing potatoes :( Oh well, back to the sterilized loam this year. Luckily for my peace of mind, I subscribe to the idea that verticillium is present in all soil to some extent, and mostly only succeeds in attacking weak, damaged, or stressed maples. (Not that I am an expert in this matter).
I had to look up solanaceaes and Wikipedia included petunias with the potatoes (and others). I guess I'll pull up the petunias - thanks for the heads up!
We share the view that Verticillium is present in some quantities in most soils. No doubt it is difficult to test for, and I would be surprised to learn if the the levels dangerous to maples are well established. None the less there does seem to be some testing capability our there: http://www.uoguelph.ca/pdc/Control_Guidelines/Vertillium_Control_Guidelines.htm Gomero, most of my garden is being converted from cow fields. There is an area where potatoes were grown, most of which has become orchard; indeed I lost an apricot to what I'm pretty sure was Verticillium there. Otherwise it doesn't appear that it's particularly numerous, so I do as you do: dig up the earth well around the roots and start again. I have replaced several maples this way so far without losses of the replacement plants. As you say, it's a recurring problem. The best solution seems to be source. The cleanest small plants I have seen come from a certain nursery in Holland, and if I am looking for a small plant I will now look there first. I will not buy maples from the DIY places any more, my experience is almost completely negative: plants that live for a year or 2 before succumbing. Although I got a great deal on petunias at the Brico yesterday! ;) -E
Hi Emery and all, Our client has decided to take a chance with a new Acer. We plan to remove the soil in the immediate area to below the root ball, and planting a new b&b, 2" or smaller caliper. Would love suggestions/ cautions, and a reliable place around NYC to obtain another A.j. 'Vitifolium' or similar large leaved cultivar. Seems it is a difficult one to find. Thanks a million. -P
