HELP, my lilacs are under attack from fungus

Discussion in 'Homeowner Assistance Forum' started by Licoricekid, Jul 2, 2008.

  1. Licoricekid

    Licoricekid LawnSite Member
    Posts: 4

    Hi-
    I have a few lilacs in my yard that I planted a few years ago and have been thriving nicely up to now. My wife discovered a kind of chalky white substance that is covering the branches, but not on the leaves at all. Several branches have reached the point where the leaves and flowering seeds have died. The fact that the leaves are not getting the white chalk on them makes me think it's not the common variety. Any idea what it is and how to treat it? Thanks.

    Licoricekid
     
  2. Rtom45

    Rtom45 LawnSite Senior Member
    Posts: 456

    Any pictures? It sounds as though your problem might be insects and not fungus. Some (for example cottony cushion scale) cover themselves with a waxy coating and remain immobile. They feed by sucking thru the stems which causes the leaf or stem to die.
     
  3. Newt*

    Newt* LawnSite Member
    Posts: 182

    I agree with Rtom. It sounds like a scale insect. Lilacs can be attacked by cottony maple scale, San Jose scale, euonymus scale, white peach scale, scurfy scale or oystershell scale. You can google each one and click on Images to see exactly which one you have.

    Horticultural oil is one defense against scale insects. I recommend Organocide which is made from sesame seeds, not Organicide is made from petroleum. Other environmentally friendly hort oils would be A-Plus, Trilogy or Green Cypress Spreader.

    Newt
     
  4. Licoricekid

    Licoricekid LawnSite Member
    Posts: 4

    I will try to get some pictures today, but I can tell you that it looks almost exactly like that fake snow in a can they sell around Christmas. But when you rub it on your finger there is a little bit of an light orange/yellowish color under the white. Thanks.
    LC
     
  5. Newt*

    Newt* LawnSite Member
    Posts: 182

    LC, still sounds like one of the scale insects. Did you google the images of each to see which is a match?

    Newt
     
  6. Licoricekid

    Licoricekid LawnSite Member
    Posts: 4

    Sorry Newt-Apparently I am as inept at transferring digitals (resizing for this site) as I am at diagnosing. I did check out the suggested scales, but they all seem to primarily attack the leaves. This stuff just fully encovers the branches. Again, it's like someone sprayed the branches with can-o-snow or confectionor sugar. At this point I am equally concerned about my Japenese Maple in close prioximity and my weeping cherry about 500 feet away. Should I be worried about all my ornementals catching this?

    LC
     
  7. Newt*

    Newt* LawnSite Member
    Posts: 182

    LC, try sizing your picture to something about the size 600 x 800.

    Maybe this will help. From this site which recommeds many chemicals I don't recommend.
    http://www.extension.umn.edu/distribution/horticulture/DG1019.html#Scurfy

    The bold in the above quote is mine. So it sounds like we're looking for an armored aka hard scale insect. Scurfy scale comes to mind. See figure 6.
    http://www.extension.umn.edu/distribution/horticulture/DG1019.html#Scurfy

    There is a cottony maple scale and a cottony maple leaf scale. Yours could be the cottony maple scale which is a soft scale. The second site has some good pics.
    http://ohioline.osu.edu/hyg-fact/2000/2019.html
    http://www.ext.nodak.edu/extnews/newsrelease/2006/061506/09cotton.htm

    From this site about Cottony maple scale:
    http://www.uri.edu/ce/factsheets/sheets/scales.html
    White peach scale isn't armored but will often just be on the branches and trunk.
    http://insects.tamu.edu/fieldguide/bimg113.html
    http://www.insectimages.org/browse/subimages.cfm?SUB=8352

    San Jose scale is another possibility as it tends to be on the woody surfaces.
    http://www.ars-grin.gov/cor/ribes/ribsymp/photos/005.JPG

    From this site about San Jose scale:
    http://www.uri.edu/ce/factsheets/sheets/scales.html
    If you can id the scale we will know which other of your ornamentals they will attack. One caveat here is that many maples are very sensitive to horticultural oils and can suffer severe damage.

    Hope that helps.
    Newt
     
  8. Licoricekid

    Licoricekid LawnSite Member
    Posts: 4

    Hey Newt-

    I hope this picture attaches okay. This is what I'm up against.

    LC

    P6050239.JPG
     
  9. Newt*

    Newt* LawnSite Member
    Posts: 182

    LC, your picture sure did come through. Wow, you have quite an infestation. :eek: I'm sure it's one of the scale insects, I'm just not sure which. At this time of the year the young usually hatch and are called crawlers. You may see them soon. It also appears the bark has split, but I'm not quite sure from the picture. If you still can't id which scale insect it is from the descriptions and links I gave you, don't feel badly as some can be difficult to id. You might want to send a sample to your local extension service for id. Just be sure it's sealed in a zip lock baggie.
    http://www.extension.psu.edu/

    It would be nice to see a picture of the entire shrub, but my thinking at this point would be to prune out any infected trunks and limbs. The best way to prune a lilac is to cut the entire trunk flush to the ground. Usually one third of the oldest trunks are pruned each year for 3 years to rejuvinate an older lilac.
    http://www.gardenersnet.com/lilac/lilac02.htm

    There might be cause for concern, but it's difficult to say without knowing which scale it is. Even if you know, scales have been known to attack plants that they aren't known to attack. Recently Azalea bark scale has started to attack crape myrtle in Texas. That's apparently never happened before.

    So, I'd say to contact your local extension to send them a sample for id, prune out the infected trunks and watch your other plants closely. Be sure to clean up any fallen leaves and debris. If you do get a positive id as a scale insect and the crawler stage is active, you can use insecticidal soap on them every 5 to 7 days until you don't see any activity. Be sure to spray the ground a bit too. You will need to watch your other ornamentals too.

    Newt
     

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