Alleopthy- Oaks

Discussion in 'Turf Renovation' started by Landgreen, Jul 20, 2014.

  1. Landgreen

    Landgreen LawnSite Member
    Messages: 249

    Many of the properties I maintain have mature oaks. The majority of these lawns struggle compared to areas in the same lawn that have no oaks. The grass is not very thick and barespots occur. With a little bit of research I've come to the conclusion that oaks are alleopathic and secrete from their roots a substance called coumarin. This natural pesticide damages other plants growing nearby so the oak tree will reduce competition for water and nutrients.

    So my question is what can be done? Is there an antidote to this coumarin? Is there a specific type of grass that does better than others in this environment? Perhaps a topdressing of compost to increase microbial activity and reseeding will help?

    I see the same pattern of dead spots around spruce trees as well. Possibly the same issue.
  2. Smallaxe

    Smallaxe LawnSite Fanatic
    Messages: 10,082

    There are lots of oak trees that have rather thick grass around its base, but indeed allelopathy is a factor in many plants... The trick is keeping the grass roots from competing directly with the Oak tree roots as much as possible...
    Competition for water/nutrients is the biggest factor, especially if the tree(s) are producing a lot of shade...
    A top dressing of compost can indeed help just be careful not to start buring the crown of the tree... :)
  3. Mark Oomkes

    Mark Oomkes LawnSite Fanatic
    Messages: 14,626

    Get a bigger flask.
  4. Landgreen

    Landgreen LawnSite Member
    Messages: 249

    Yeah Ive got one customer that will get compost and seed. Its a small area so should be an easy job.
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  5. Landgreen

    Landgreen LawnSite Member
    Messages: 249

    Up to a barrel now...
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  6. Landgreen

    Landgreen LawnSite Member
    Messages: 249

    Well I've been spelling Allelopathy wrong. That probably would have helped my google research a little better.

    Pass the flask Mark... :dizzy:
  7. RigglePLC

    RigglePLC LawnSite Fanatic
    Messages: 13,288

    My grass grows fine under oaks--except where it is too shady.
    Ground covers like myrtle, pachysandra, lamium, ferns and euonymous do fine under oak trees in shady spots.
  8. Landgreen

    Landgreen LawnSite Member
    Messages: 249

    Some pics. This lawn is very healthy yet large areas are sparse or bare near large oaks. To the right in the background is lush lawn. There is a definite border where it is affected.

    dead spots Fishers Run1N.jpg
  9. Landgreen

    Landgreen LawnSite Member
    Messages: 249

    Here is the front yard. The lawn is fine except near a large oak. Some of the lawn along the edge of the woods has dead spots as well.

    dead spots fishers run 2.jpg
  10. Landgreen

    Landgreen LawnSite Member
    Messages: 249

    Here is another example. This is not an oak. I believe it is an Alder but not positive. The affected areas have been seeded twice the past two seasons with no results. There are several of these trees on this property with dead areas of turf near them.

    Dead spots near tree Arbors.jpg

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