leaf rollers

lanurse(8)October 19, 2008

Any new suggestions for leaf rollers? I have had a terrible time with them this year... It seems to be getting worse (mid summer to now-fall)I've tried different insecticides and every nite I cut off the affected leaves but new ones keep appearing. How can I get rid of them so they won't come back next year? I live in Shreveport, LA.

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What are leaf rollers? Pictures please so I know next time.

    Bookmark   October 19, 2008 at 6:20PM
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They are actually a moth that lays her eggs on canna leafs, seals the leaves with a sticky web substance and make for unsightly cannas.

I have a couple of questions Lanurse. Do you have alot of other blooming flowers around your yard. When you grow a butterfly garden like I do, or you have alot of other plants blooming the butterflies will come to your yard. Along with them a bunch of the moths come. This year has been terrible trying to fight them and stay ahead.

I have cannas everywhere and it has been a chore for me. They go through several different laying periods and if you can break the cycle your way ahead of the game. As for me I never could get them in control. I spent hours and hours walking around, unrolling the leaves, squashing the little boogers and cutting leaves off every day. I hope that your burning everything as your cutting the leaves off. If not they just go ahead and live. The grow and then fly away to start the cycle all over again. I think you will probably have to spray every 2 to 3 weeks to keep them in control. If your lucky and can break the cycle you may be able to get rid of them. But I wouldn't hold my breath.

Since it is so late in the year and the weather is turning cooler at night I wouldn't worry too much about them. Just be sure to cut them all down to the ground after or right before the first frost and BURN EVERYTHING. Then stay on some kind of spraying schedule next spring. Do not wait until you see a bunch of them on your cannas to start your spraying.

Good luck and let us know how things turn out.

    Bookmark   October 20, 2008 at 1:12AM
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Look into using rotenone as a broad spectrum insecticide. It is organic, has a short half-life, and is very effective.

    Bookmark   October 23, 2008 at 12:06PM
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The leaf roller question seems to be an often discussed issue. Those of us growing in the Southern third or half of the U.S. can and most assuredly will deal with this issue. Those growing cannas in the northern half of the country tend to see little or only moderate infestations of the canna leaf roller. The options each have are typically related to location. Many of our more northern gardeners can take a more environmentally friendly approach and try Bt (bacteria thuringiensis) or other bio-control agent once the problem becomes evident. Southern canna growers can choose to contend and accept the leaf roller decimation or learn to safely use a good systemic insecticide such as Orthene (acephate). For the deep southern grower, they need to start early and spray regularly on a 10 day or two week cycle. Total control might require a once a week application up until near the first frost or plant dieback.
Contact insecticides are basically useless for control of the canna leaf roller.
Regards, Kent

    Bookmark   October 23, 2008 at 11:45PM
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BT or trichogramma wasps will do it!

    Bookmark   October 24, 2008 at 5:32PM
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funinthesunincl(Z9 TX Gulf Coast)

Kent: "Contact insecticides are basically useless for control of the canna leaf roller.
Regards, Kent"

What is a contact insecticide?

And Sylvia...you recommend BT -- do you use the BT that is in a mosquito dunk? Or what form and manufacturer do you use?

I have some of my 'prized cannas', like Pink Sunburst, in a couple of big pots. Since I live in Houston, we generally leave our cannas in the ground. Would we have a better 'handle' of leaf rollers if I took them out of the dirt/pots in the winter, cut them back, cleaned them off, and stored them in some other medium than dirt? Should I spray them when they are out of the dirt?

I would appreciate any suggestions!

Thanks in advance!!!

Mary Jane

    Bookmark   November 2, 2008 at 10:00AM
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Mary Jane,

Thank you for signing your note. Contact insecticides typically must be able to come into physical contact with the pest to be effective. Many of our typical household sprays such as ÂRaid Flying Insect Killer or ÂHot Shot Roach & Ant Killer are typical contact insecticides. You will find the same type of insecticides available for our plants and gardens. Many of our outdoor contact insecticides rapidly become diluted or their effectiveness is inhibited by our inability to apply the product in a manner that makes pest contact.
Contact insecticides can be very useful for pests that are living on the surface of the host, but have little value for pests feeding or living inside the host. If you cannot see the pest, you generally need to consider using a pesticide that the host can absorb and disperse internally to its growing parts. The pest will then contact and consume the pesticide. This type of insecticide is generally referred to as a "systemic insecticide". You spray a systemic insecticide on the plant, the plant absorbs and disperses the product internally and the pest can now be connected to the product when it feeds on the plant. Because night flying moths are responsible for laying eggs and tightly rolling and sealing the canna leaf, typical contact insecticides or bio agent are unable to make contact with the internal pestÂs larva. Systemic insecticides are our most effective means of reaching this pest.
Storing your cannas in their growing containers is not a problem. Simply remove and trash the plant foliage and prevent freezing of the rhizomes in the containers. Once new growth begins in the spring, I would begin a spray program with Orthene (acephate). You cannot totally prevent the moths from rolling the leaf and laying the eggs. You may need to carefully unstitch some of leaves to maintain good appearance but the larva will not survive and the leaf should then unfurl and remain healthy as long as your spray program is adequate. By the way, do not use Orthene on your plants near fish ponds and follow label recommendations.


    Bookmark   November 3, 2008 at 6:32PM
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