Sick Vinca - Why?

Discussion in 'Lawn Mowing' started by DFW Area Landscaper, Aug 16, 2004.

  1. DFW Area Landscaper

    DFW Area Landscaper LawnSite Silver Member
    from DFW, TX
    Posts: 2,116

    I'm posting this in the lawn care forum so more folks will see it and respond sooner.

    This spring I ammended the soil in the beds of my tree rings. My employee and I took 5 gal buckets and mixed approx 20% top soil, 20% lava sand and 60% landscapers mix, which is really just very finely ground mulch, and laid about a 4" depth of that on top of the clay soil in the tree rings. The petunias did very well for a few months and then it simply got too hot, so I switched to Vinca.

    I planted this Vinca about July 12th or so. I put 4" Vinca in and liquid fed it weekly. About two weeks ago, some of the plants started to look drought stricken, so I increased the watering frequencies. They continued to deteriote, so I decreased the watering intevervals. Then they all started showing signs of drought stress. So I really soaked them and the healthy ones look great, but the diseased ones are really looking horrible.

    I think I might have Phoma Blight Fungus http://www.ag.uiuc.edu/cespubs/hyg/html/200009c.html It has been cool here the last two weeks with over night lows in the upper 60's. About the time it cooled down was the time the disease started happening.

    However, having said that, the Vinca in my hanging baskets (which are soiled in pure 100% peat) and in my clay pots (which are also 100% pure peat) aren't having any problems at all.

    Here is a picture of the diseased Vinca in my tree rings.

    Later,
    DFW Area Landscaper

    sick vinca 1.001.jpg
     
  2. DFW Area Landscaper

    DFW Area Landscaper LawnSite Silver Member
    from DFW, TX
    Posts: 2,116

    I know the problem isn't wet feet. I dug a couple of the 4" root balls out of the soil. The soil isn't saturated at all. Here is a picture. Notice how the roots are white...wet feet will produce rotting roots, which are black.

    sick vinca soil & roots 1.001.jpg
     
  3. DFW Area Landscaper

    DFW Area Landscaper LawnSite Silver Member
    from DFW, TX
    Posts: 2,116

    Here is a picture of the Vinca in my clay pots, just a few feet away. They are in pure 100% peat.

    healthy vinca 1.001.jpg
     
  4. DFW Area Landscaper

    DFW Area Landscaper LawnSite Silver Member
    from DFW, TX
    Posts: 2,116

    Lastly, here is a picture of the Vinca in my back lawn. It too is in 100% pure peat.

    healthy vinca 1.002.jpg
     
  5. DFW Area Landscaper

    DFW Area Landscaper LawnSite Silver Member
    from DFW, TX
    Posts: 2,116

    I'm thinking the clay in the soil is the problem. It seemed really airy when we mixed it dry. But now that the soil has been watered a few months and set for a while, it's still good soil, but not nearly as airy as peat. I'm guessing the fix is to dig up the soil mix I made, remove it, and install a new 4" soil composed entirely of either landscapers mix (which is just very finely shredded wood) or use 100% peat, which would be a lot more expensive.

    Any suggestions?

    Later,
    DFW Area Landscaper
     
  6. NickN

    NickN LawnSite Bronze Member
    from Alabama
    Posts: 1,010

    Have you checked the pH of the soil?
    Vinca prefers 6.0-6.5.The lava sand you added raises the pH,possibly to over 8,but the peat lowers the pH.
     
  7. DFW Area Landscaper

    DFW Area Landscaper LawnSite Silver Member
    from DFW, TX
    Posts: 2,116

    Kelway is reading 6.2 on pH.

    My gut feeling tells me to replace the soil I created with 100% organic matter. Anyone ever have any flowering annual disasters with 100% organic matter?

    Later,
    DFW Area Landscaper
     
  8. NickN

    NickN LawnSite Bronze Member
    from Alabama
    Posts: 1,010

    That blows that theory then.
     
  9. DFW Area Landscaper

    DFW Area Landscaper LawnSite Silver Member
    from DFW, TX
    Posts: 2,116

    Anybody else have any ideas as to what is wrong with this Vinca?

    Later,
    DFW Area Landscaper
     
  10. TClawn

    TClawn LawnSite Silver Member
    Posts: 2,036

    I don't think that the clay is doing it, because one of my customers has some that are growing in almost pure clay and there doing wonderfully.
     

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