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daniel_cl

Preventing White Pine Weevil on young eastern white pine

16 years ago

Hello,

We live in Ottawa, Canada. Just today we planted a 4-foot Eastern White Pine (Pinus strobus) in the front yard that faces south.

We are worried about white pine weevil, although while taking walks in the neighborhood we don't see any weevil-damaged conifers. The reasons for our concern are:

(1) The tree sits in the open (=obvious target) and will receive full sun light all year round (=preferred target).

(2) We have poorly drained heavy clay about 6" below the surface (= poor drainage = attracts more weevil). To combat drainage and clay, we planted the tree ON the ground level and made a 2.5'-in-diameter x 1'-high mound to go with it. The mound is made by 1-1-1 mixture of top soil, play sand (= better drainage), and garden earth. Finally, we covered the mound with 2" of red cedar mulch.

After some online research, we found a way to prevent the weevil - to wrap the leader with cloth and surround it with circles of tapes with the sticky side facing out. Since the tree is still young, we can easily do it for 10+ years with the help of a ladder.

But we wonder whether this method is going to hinder the tree's growth and its annual branching. And whether the method is effective at all. And if not, whether there are other ways to keep the weevils away from our tree.

Thanks for your help.

Comments (11)

  • 16 years ago

    I have never done anything to prevent weevil attacks, but I have read the same things on-line that I would guess you have. My understanding of the wrap and the sticky stuff placed on it is this: the weevils are weak flyers and tend to crawl up the trunk rather than fly. The only part of the tree you need worry about is the leader, so one wrap below thatÂas high as possible without trying to place it over where there are still needlesÂis all you can do. After the tree is taller, I think one wrap as high up as you can conveniently place it would be a good idea. Perhaps you could do two, but I am not sure what the extra benefit would be.

    Also/or you can spray the leader with some kind of pesticideÂI forget which, but you can find out on-line. The main problem with that is proper timing--sometime in fairly early spring. You can find out about that also on-line. This may be the best option while you can easily apply the spray to the leader. Your chance of successÂif you get the timing right (of course you can do more than one application)Âshould be greater. With the sticky stuff, there is always a chance that a weevil could avoid it and fly directly to the leader while the tree is still very small.

    Maybe someone at your local ag extension or forest service can help.

    Where I am the white pine weevil attacks spruce much more than white pine. I am not sure why. With spruce it is not so much of a problemÂonce in a while a tree is disfigured and/or develops double leaders. With repeated attacks white pine is much more severely affected. In areas where the weevil is a big problem, white pines develop multiple trunks in a kind of "cabbaging" form. These trees can be attractive in their own way, but generally it is better to try to stop the attacks. If you have a lot of white pine in your area, and if most of them have straight, single trunks, maybe you donÂt need to worry much. If you get just one or two attacks, you can help the tree re-establish a leader and suffer no real harm long-term.

    --spruce

  • 16 years ago

    sounds like a lot of worry for something that may never happen .... especially prophylactic chemical use ...

    in my z5 MI .... near the OH border ... white pine grow 3 to 5 feet per year,once established .... re-leader extremely quickly ... and are basically weed trees ... in the sense that you cant beat them back with a stick ... once they get going ....

    some of your presumptions MIGHT be wrong ...

    the fact that it is in the wide open.. suggests not just your conclusion.. but the conclusion that the odds of any given bug finding it low ...

    and that you will be able to ladder up the thing for 10 years ... i would bet on MAYBE 3 years ... since you wont be putting a ladder up against fresh weak growth ....

    so.. i would wonder if all your worry is worth it ....

    also .. given their growth rate.. i hope you planted it a good 20 to 30 feet from your house .. they are not strong wooded ... and subject to shedding large parts in 20 or 30 years.. in harsh weather.. like winter ice storms and wind ....

    good luck

    ken

  • 16 years ago

    Thanks for the response and information.
    We planted the white pine 27 feet from the house. So there should be plenty of room.

    Let's hope that the white pine grows fast and well. I was just advised by a local nursery owner that I should wrap the entire plant up just for the first winter.

    I also noticed that the very tip of the pine's leader seems to have been cut - it is covered by some white saps. This happened to almost all 4' white pines we saw in the nursery. I hope there is nothing to worry about.

  • 16 years ago

    Daniel:

    Snipping off long leaders of nursery stock is a common practice. It is not a problem, unless done too late. If you have buds at or near the top where the leader was cut, no problem.

    --spruce

  • 16 years ago

    Thanks for the comments.

    When I look at the white pine's clipping wound on the leader, I don't see any bud. But there are buds on the side branches.

    I looked up some white pine pruning information online. This is my guess: losing the bud = no further growth. Therefore, clipping of the current leader force a second branch to take over (I noticed that some of my tree's side branches are curling upwards). Perhaps the clipping force the tree to growth slower, therefore spending more time to put out side branches.

    Should I prune the white pine in the future, too?

    Thanks.

  • 16 years ago

    This evening we closely observed some white pines in the neighborhood. We found this bug on the still-green cones. Several of them per tree, only present on cones. The cones were dripping saps. We were concerned and "took a sample" home, worrying it is the feared weevil.

    http://www.hksan.net/maltzXD/temp/white_pine_cone_bug.JPG

    We found a positive match on the web: Leptoglossus occidentalis, or leaf-footed pine seed bug - not the weevil.

    According to this website, this bug doesn't really harm the tree.
    http://www.bentler.us/eastern-washington/insects/leaf-footed-pine-seed-bug.aspx

    The bug walks slowly. Probably because their legs are full of sticky saps?

  • 16 years ago

    Daniel:

    The buds at the top of the cut leader may not have formed yet--it is still a bit early. If you don't see any buds by September, the leader may have been snipped off incorrectly--too late. If that is the case, you may--beginning early next spring--have to help the tree develop a new leader. If that is the case, get back to us then. Briefly, you can tie up one of the side shoots to an erect position, and/or trim selectively a few of the others. If at that time you decide you want our advice about that, a picture can help us give precise advice about just what to do. But it is easy--nothing to worry about.

    --Spruce

  • 16 years ago

    Thanks. I will wait and see whether the leader regains its buds.

  • 16 years ago

    Just a little update:

    The snipped leader of our white pine has shown some interesting new growth.

    An unhurt branch usually has 1 central bud and 5 side buds together. The snipped leader has grown 1 new bud sprouting new needles, and 5 slightly lower, smaller, side buds also growing some needle. Looks like they will become the new leader and sidekicks for the 2011 season (if they harden soon enough for the winter).

  • 16 years ago

    Daniel: Yes, perfect. Thanks for the update. Once in a while the new leader will be challenged for dominance by the top whorl of previously growing laterals. If that continues after two or three years, you can, or let me say I would advise you to, shorten the competing laterals. This usually doesn't happen, but I have occasionally seen it.

    --spruce

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