Apple Scab-Cedar Apple Rust ?

Discussion in 'Pesticide & Herbicide Application' started by Mgardner, Apr 5, 2003.

  1. Mgardner

    Mgardner LawnSite Member
    Messages: 156

    Last year as I maintained a commercial facility under contract the mature crabs all wilted upon warm -hot weather. Lost leaves and one of our Lesco reps claimed it was apple scab,treat early next year with dormant oil on lower main limbs and trunk. With "spring" here buds are appearing and after discussing the symptoms with another contractor he thought it was cedar rust, and couldn`t remember what they had used. Then if diseased I`ll have to treat the canopy? Hoping to nip it in the bud this year so they look good.:cry:
  2. TSM

    TSM LawnSite Senior Member
    from MA
    Messages: 707

    sooo, lesco says treat apple scab with dormant oil???

    Dormant oil is an insecticide

    apple scab is not insects!!!

    treat with a fungicide, many products labeled for control, you might want to go with Mancozeb because it is also labled for cedar-apple rust.

    Cultural practices such as pruning to increase air circulation and sunlight penetration will help. (apple scab)

    anyway, my opinion is always get a second opinion from what lesco says

    good luck
  3. Mgardner

    Mgardner LawnSite Member
    Messages: 156

    Person from Lesco facility that suggested dormant oil is no longer employed there. Spoke with the regular guy there this AM and he has a product I believe ,he called it Maintain , nevertheless like I told him I will need to treat this outside the contract , therefore obtaining approval before application. Think I have 22 trees affected and contract with facility includes a dormant oil treatment early each spring. I maintain the lawn and beds as well as shrubs ,sub out the irrigation clean-out and repair. Definately hoping to reign in this problem with the crab trees in house.
  4. EJK2352

    EJK2352 LawnSite Bronze Member
    Messages: 1,150

    I have a condo development with 14 crabapples. These crabs are a variety that is very susceptible to scab. I treat these tree's with Banner Maxx fungicide. I have had excellent control with Banner Maxx and it was a very low use rate to control scab. I highly recommend this product. :) ;) :) ED
  5. GroundKprs

    GroundKprs LawnSite Bronze Member
    Messages: 1,969

    There are numerous crabapples now out that are resistant to apple scab. To maintain susceptable varieties requires frequent applications of fungicide, especially in a wet spring. The proper cultural practice for apple scab control, for the last 20 years, has been to replace the trees with resistant varieties. Yes, chainsaws can be proper cultural care, LOL.

    Discuss problem with client. Replacement can be a much cheaper long term maintenance procedure, compared to regular fungicide treatments.

    If you have cedar apple rust, either remove the apples or cedars. The fungus has an annual cycle moving back and forth between the two plants. Eliminating one host interrupts the disease cycle.

    Loading up the fungicide gun may be effective in the short term, but it is often the wrong cultural approach. You are just fixing the symptoms, not the problem.
  6. KenH

    KenH LawnSite Bronze Member
    from CT
    Messages: 1,622

    Does anyone know the distance between apples/cedars where the disease is transmittable? If I remember correctly, it is pretty far.
  7. dougaustreim

    dougaustreim LawnSite Senior Member
    Messages: 488

    Your problem most likely is apple scab. Treatment can be effevtive, but timing is everything. If it is a damp spring, you may have real difficulty treating them appropriately to get good control. For sure one should check very closely for susceptibility before planting any crabs.

  8. philk17088

    philk17088 LawnSite Fanatic
    Messages: 17,386

    I've had more problems with C-A rust on hawthorns more than I've ever had on Crabapples. I will treat it but I won't guarantee anything. Too many variables and customer has to understand one app of fungicide in a cold wet spring will not control anything, multiple apps by label and they are paying full price for each app. If they have crabs,hawthorns they will need possibly 4 apps to keep disease suppressed, especially the trees that are never pruned properly. Disease control on trees is a tough row to hoe.
  9. Turfdude

    Turfdude LawnSite Bronze Member
    Messages: 1,899

    If there are any near by junipers, remove them. Remember there are 2 host plants for this problem.
  10. Mgardner

    Mgardner LawnSite Member
    Messages: 156

    I`ll scout the area tommorow and see if there are any cedars nearby. There are Junipers ,but they are groundcover. Appreciate the info ,it gives much needed light on a subject that has obviously been ongoing for many.

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