What's killing Rododendrums everywhere?

Discussion in 'Pesticide & Herbicide Application' started by HenryB, May 29, 2006.

  1. HenryB

    HenryB LawnSite Bronze Member
    Messages: 1,853

    It seems Rodo's are looking half dead. Is there a specific blight or insect thats killing them in the northeast? If so any specific treatment recommended?
  2. philk17088

    philk17088 LawnSite Fanatic
    Messages: 17,386

    There was a lot of winter drying from lack of moisture and persistent wind thru the winter. Phythoptera fungus has been a big problem the last couple of years. Even new nursery stock seams to have it.
  3. ProMo

    ProMo LawnSite Bronze Member
    Messages: 1,468

    I am seeing a lot of what looks like Phythoptera on azaleas down south as well
  4. procut

    procut LawnSite Bronze Member
    Messages: 1,852

    Rhododendrons are an acid loving plant, if the soil pH is to high they look 'sickly'. This might have something to do with it.
  5. jameson

    jameson LawnSite Fanatic
    from PNW
    Messages: 7,472

    I know that in WA state, especially during the past several years, there have been a number of reported cases of phytophthora ramorum -Sudden Oak Death/SOD breaking out in nurserys. Many wholesale nurserys were quarantining rhodys, azaleas, viburnums etc. and destroying whole lots of plant material.

  6. SodKing

    SodKing LawnSite Bronze Member
    Messages: 1,641

    Yes I went to a lecture on P. ramorum this winter. Its not up here yet but it is in NJ. Take a cutting to your extension agent and have them classify the fungus and then take appropriate action.
  7. upidstay

    upidstay LawnSite Bronze Member
    from CT
    Messages: 1,584

    They are also a shallow rooted plant, and take a big hit during droughts. Phytopthora has been bad lately, even though the text books say it is minor and rarely kills anything. Black vine weevil is a huge problem too. The larvae live around the base of the plant and gnaw away on the stem girdling it and usually killing it. Water it regularly, deep root with merit and something like Bolster or Roots, and prayer works too.
  8. americanlawn

    americanlawn LawnSite Fanatic
    from midwest
    Messages: 5,955

    Yep ---- then there's "canker". It's common on rhododrendrons & azaleas.

    These ornamentals do best in southern states where they are routinely "replanted" every other year. ie: "raise them".

    Most successful growers replant them in a mound (slightly higher than ground level) every 2 or 3 years - each time adding more organic material to the soil.

    Keep an eye out for "chlorosis" (pH induced) as these plants need an acidic soil to thrive. They do not like hot afternoon sun or cold nothern weather.

    If the plant is growing under healthy conditions, the abovementioned "diseases" will, for the most part, be a thing of the past.

    "Mir-acid" is good for feeding these, but it should preferrably be done just before the "new growth" begins in the spring. (Fe, Mn, etc are translocated to the new growth - thus, don't wait 'til fall). I suppose June is not too late?
  9. Tharrell

    Tharrell LawnSite Silver Member
    Messages: 2,967

    Would pine needles be better for these rather than mulch? I have several of those plants and put some mulch out around them for the first time.
    I snapped the last pics a couple of days ago. Seems like some kind of fungus on the mulch.





  10. SodKing

    SodKing LawnSite Bronze Member
    Messages: 1,641

    That is what we generally call the "Dog Puke mushroom" pick it up with a shovel and throw it away. I cannot offhand recall the actual name of the fungus.

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