The developer in my neighboorhood was so kind as to plant trees in everyone's yard. But after 3 or 4 years all but one or two (so probably 180 or so) look scrawny and pathetic. I know nothing of horticulture, so I was wondering if anyone knows what kind of tree this is. Also, it looks like it's diseased as do all of the others. Is there a way to fix this, or are they all doomed to be terrible?

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3 Answers 3


This is definitely an Acer, but what you're seeing there is a case of Rhytisma acerinum, commonly known as Tar Spot of Acer, or Acer Leaf Spot. It's a fungal infection, and in the UK, there is no effective fungicide treatment available, though you may find there is something you can use where you are.

This infection doesn't kill the tree, but it can make it look unsightly (as you've discovered). Some control can be effected by removing fallen leaves, particularly in Fall, because the spores over winter on the leaves. Removing the worst affected leaves might help, but I'm not convinced it makes any difference other than to reduce the aesthetic effect a bit.

UPDATE: Regarding sun burn from water spots, this isn't possible. I was shocked when I found out it was a myth, been warning people about it for years, but the original tests for this theory were performed with water droplet sized glass placed on leaves - the leaves burned. But when the same tests were performed with real water droplets, on both smooth and non smooth leaves, no damage could be reproduced. Water droplets have a different refractive index from glass, and don't maintain their shape, which isn't true of glass droplets - the water also cools the leaf surface generally. Further, I've tested it myself when the temperature on my very sheltered balcony has been 55 deg C in direct sun by placing droplets on a Foxglove leaf, which is ridged and not smooth. No damage resulted. Reference: www.AmericanScientist.org/issues/pub/sunburned-ferns.

UPDATE: Laughing-Jack may well be right when he mentions Phyllosticta - I jumped to Tar Spot, but actually, looking at it again, it might not be, but I'm 100% convinced this IS a fungal leaf spot - whether its phyllosticta or another type. I suggest you check to see if there are any fungal sprays or treatments you can use in your area - the UK is very short on effective anti fungal treatments, but maybe its better there. Point given, LaughingJack, though I'm not sure that counts for a comment - post as an answer!

  • That isn't tar spot. the pattern on the leaves is similar, but this doesn't have the black smudge which gives tar spot it's name. Neither is the tree starvibg the area.
    – J. Musser
    Commented Jul 3, 2014 at 11:30
  • @J.Musser,not sure what the second part of your comment means, but we'll have to agree to differ on this one - this infection looks much worse on Acer pseudoplatinus than it does on other maples, but it still affects other varieties.
    – Bamboo
    Commented Jul 3, 2014 at 11:32
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    @J Musser: Only bacterial leaf spots have a yellow halo, and not even all of those. Fungal ones don't have this feature.
    – Bamboo
    Commented Jul 3, 2014 at 13:07
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    I thought tar spot was also generally much bigger and tar-like on the leaves. Phyllosticta leaf spot is one that I'd seen mentioned as a smaller and more contained (doesn't show the yellowing around the 'spot') type of leaf spot. missouribotanicalgarden.org/gardens-gardening/your-garden/… has a decent collection of images and UIUC has a decent paper at web.aces.uiuc.edu/vista/pdf_pubs/648.pdf Commented Jul 4, 2014 at 1:42

That is a Red Maple, Acer rubrum. The damage resembles fungal leaf spot.

They were obviously planted at near the same size they are at now. They were probably 5-7 years old at planting, and planted as a balled and burlapped tree. You can see the last year of growth from when they were at the nursery. It is about the top 1/4-1/5 of the tree. When a tree growing that fast is dug, more than half of the root system is removed. If the top isn't pruned properly, the plant will not be able to grow well, and will only put out leaves with very little terminal growth.

Cases like this are very common where I live. Here's what you can do:

  • Prune the whips of the last nursery-years growth by about two-thirds. This will put the tree back into (somewhat) proportion root-wise. Always cut back to a comparatively healthy outward facing twig/growth bud.

  • Start giving some growth stimulaters. The tree hasn't got many roots in the lawn, which obviously has had some nitrogen. Use a balanced, but fairly high nitrogen slow release fertilizer. This will give the tree something to build with.

  • Again, the tree doesn't have a great root system. Water very deeply if the ground has been dry for two weeks or more. If it doesn't rain, water deeply only once per week. If the ground is constantly moist, the tree will grow a shallow root system.

  • You should be able to easily see the root flare of a tree. Pull the mulch/soil away from the base of the tree until you find where it widens, and lateral roots appear. When a tree is planted too deeply, the roots will start circling the trunk of the tree, and can cause lots of damage that way. This is one of the biggest problems I run into on new properties that had a less than ideal landscaping job. Keep the mulch a couple inches from the trunk.

  • Stake you're tree. The tree will benefit from some support, as rocking at ground level will cause major root severing and will greatly set back even an otherwise healthy tree. I would use two 6' 2x2" stakes, pounded at least 18 inches into the ground, placed opposite each other, with the tree directly centered. Do not pound the into the root ball. The edge of the mulch should be fine. Use wire to hold the tree up, but allow some play. Measure the distance between the stake and the tree, and multiply that by 21/2 times, for your wire length. Put some form of padding in the center to protect the trunk. I use 8" pieces of cut hose. Put the wire in place and wind the ends around the stakes. You can tighten these by inserting your pruners or similar between the wire strands and spinning.


I believe this is Acer rubrum. Red Maple. There are a couple of things you should check:

  1. How deep this tree was buried. A very common contractor thing. Make sure that the bark is out of the soil and mulch. Only the roots should be buried. Your picture tells me the mulch is up too high on the bark of this tree. Pull it away, 6" or more. Moisture being held next to the bark of woody plants will encourage bacteria. They will kill the vascular system within a year or two.

  2. Have you ever fertilized this tree? Your tree and lawn shows nutrient deficiency. Contractors pretty much strip the good soil away and you need to get organic matter into your soil. Fertilizer alone won't work. Get decomposed organic matter and spread 1/2" over your lawn, aerate (pull soil plugs out of lawn and allow to disintegrate), get rid of the chunky wood mulch around the tree and elsewhere. Use Dr. Earth's Lawn Fertilizer...incredible stuff. Also puts bacteria into your soil. Get mycorrhizal fungi to add to your soil. It might come in that fertilizer, I know soil bacteria is added. If not, you can get it separately.

  3. Don't worry about the spots on your leaves. It is fungus and the plant itself, is killing the infected tissues causing the spots. Don't water late in the day or at night.

The best mulch is human poo mixed with sawdust. Completely decomposed, it won't smell the same, it is a fine-textured dark taupe, no rocks, no weed seeds, no pesticide residues and no funky smell! Completely different product! If you can find this stuff, use it on your lawn, all your plant beds. I wouldn't even weed. Just put this on your lawn (1/2") and 2" on your plant beds. For shallow rooted plants like rhododendrons, azaleas, daphne...only 1" around their drip line. Keep away from the base of trees, shrubs. Not recommended for vegetable gardens as a little high in heavy metals.

Mow your lawn no shorter than 3". Trust me, try this. When you water, water deep!!! 4 - 6"!!! Then allow soil to dry out. Your footprints should be clear when you step on the grass. The blades don't bounce back up. Then! Water deeply. Check the depth. If you are watering everyday, your lawn, your plants, your tree have shallow roots and are stressed and are in danger of dying. You will actually save money watering this way. Mow once a week or twice is better. Sharp blades! No shorter than 3"....no shorter than 3". Aerate once a year.

Ideally, we treat plants separately from lawn. This tree should thrive taking care of your lawn correctly. Get a test of the pH of your lawn. It should be 6.5-7.0. If not, apply lime but stay away from the drip line of your tree. It likes slightly more acidic than a lawn.

This should get your tree growing and your lawn lush. Let us know what you decide and send another picture, same spot, taken a couple of months from now?

  • Smart mind think alike (and sometimes so do ours) :)
    – J. Musser
    Commented Jul 3, 2014 at 2:42
  • So all of these spots are from sun magnified in a water drop and burning the leaves? Sounds good to me! Come on...look what we try to do with so little information. Grin. Spot on!!
    – stormy
    Commented Jul 3, 2014 at 6:36
  • I've never fertilized the tree. I didn't even know about that until recently. The lawn is a mess. It was covered in white clover. I tried putting down some Scott's Weed & Feed in the Spring, but something must have been wrong with the spreader or something because I only used like 5-10% of the bag when when I should have went through something more like 65%. The grass has tons of thin spots and more than likely I need to de-thatch it as well. Since it's the summer (95 degrees the other day), I don't know what I can really do at this point. Commented Jul 3, 2014 at 13:48
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    The color of the leaves are a lighter green than they should be, to me this is nutrient deficiency. Yellow rings might have already blackened. Aeration would be better than thatching. Thatching should only be done if you can see an inch of thatch build-up. If you use fertilizer with bacteria that break down thatch, you might not ever have to...Dr. Earth Lawn Fertilizer...hate to push any product, but this was amazing. By now there should be similar products, organic, extended release, bacteria, mycorrhizae. Good for the lawn and the tree. pH test for liming.
    – stormy
    Commented Jul 3, 2014 at 17:38
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    @stormy, some good info here, but any suggestion of human poo as compost makes me nervous. It can be used if composted properly, but I was told it's usually recommended against akin to not using meat byproducts in composting. Do you have any more info to clarify that, or would it be best to just leave the compost specifics out and just say to top-dress with a good compost? Commented Jul 4, 2014 at 1:30

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