Parasites

[gamekeeper]

I was told Iris that have a slit in the foliage have a worm that can be removed ?This time of year is this also true or does the summer take its toll?

[BillyB]

Are you referring to a split at the base of the foliage just above th rhizome? If so, I don't believe it to be critter damage. Probably due to growth spurts. I've had it on several TB cultivars this year. The worm you may be thinking of is the "iris borer".

Garden & Be Well
BillyB

[petal*pusher]

ARGH! Those dastardly little wigglers! I had to throw away an entire clump this summer after finding it severly infested with iris borers......I'm afraid to look too closely to my other iris......

I should have known when there were so few blossoms. Info I read said to "get them out of your yard"....so I wrapped up the entire clump tight and dumped 'em.

Pictures and info in this particular forum got me excited about iris...and I added several to my gardens...still love, love, love them, but know I HAVE to pay attention to the rest to make sure there is no infestation.

How exactly do the rest of you deal with borers?????....................Thanks much! Pam

[plantaholic]

Hello, everyone : I'm the newby here; hope you don't mind my two bits' worth.

I've been using Cygon up to now, but not so sure if the remainder that I still have
is still effective after about three or four years on the shelf. I continue to meter it
out on new ones as I set them out. So far, so good.

Now here's a brainwave I want to hold up for opinions. The evening air in the
backyard where my new yellows are set out is alive with moths which swarm around
the outside light by the backdoor.



figure its worth a try in at least thinning out this threat. An better ideas out there?



T

[otnorot]

petal pusher you should have saved a few uninfected rhizomes. If a iris borer gets past me during the summer I lift infected rhizome and dig borer out with my knife then replant rhizome.
Bill
Growing and hybridizing iris for 59 years.

[petal*pusher]

Thanks Bill...great suggestion! I hated to just toss that big clump...but it was pretty badly infected. Stil have to take the time to check the other beds.

And Plantaholic...makes common sense to me that the secret is to get the moths!

[Chris_W]

Hi,

I try to watch early in the season (April/May/June) for those streaks coming down the center of the leaves, in the creases where the leaves intersect. That's a sign that the iris borers have started their trek down the leaves into the rhizomes. If I see those streaks I get out the insecticide and spray the leaves to saturation, hoping that it will run down into the leaves and kill them. I use Sevin, Malathion, and Merit. The Merit is in Bayer 3-in-one, a systemic that I use often on the Hibiscus, so stop and spray the Iris once in a while too.

If I get a really bad infestation I also have a small amount of Lindane that I will spray - that really does the job, actually I've heard it lasts a few years, so I use it very sparingly.

Now, if you do miss the early signs, you will often see the tunnels get bigger, with caterpillar poop coming out of the leaves as they grow bigger and bigger. At that point you can cut down the foliage to try and find it and then squish it. By now, this time of year, the borer will have reached the rhizomes. Best way to get them now is to lift, kill it by hand, then replant, although if you really have a lot of them you might try saturating the soil with an insecticide. I agree, you really don't need to throw away all of it, as there are usually some lateral new rhizomes that will still be okay. The really bad ones can be pitched, though, as they often get a secondary fungus infection when really badly damaged.

In the fall it is highly recommended to cut down and throw away ALL of the old foliage from the Iris. That is where the borer eggs will overwinter, so throwing away the foliage can cut back on the population for next season. I do notice that areas that were bad one year tend to get worse the next if I don't get after them.

Hope that helps a little too.

Chris

[petal*pusher]

Thank you so much for the information! What I love about "this place" is thruout everyone's posts...their love, admiration, and respect for each particular plant species is so apparent....and then their ability to give such helpful hints and info is so readily shared!!

I know what I'll be doing this weekend...gather up my scissors and get out to those iris! Thanks again all!!.......Pam

[Garden_of_Mu]

Chris' advice is spot on. I am so thankful that we don't have those nasty little things out here. But from friends baak east I can attest the best thing you can do to keep them out is to clean up dead foliage every fall after a hard killing frost and then again in the spring before the temps reach 70 degrees. You want to get all the old foliage of any plants that are near the irises out of the garden as well. The moths will lay eggs on any nearby leaf litter, not just iris fans.

I also agree that if there is a really heavy infestation try and find a fan or two on the side to salvage before tossing the clump so you don't lose the variety (unless you didn't care for it anyway and want an excuse to shop for some new ones ).

[plantaholic]

Here's yet another site relating to this topic. Click photo:



I've deployed my UV Zinger already. No results yet after one night.

[plantaholic]

I'm leaving the UV Zinger on all night now, and who knows; it may do some good.



My remaining supply - half a bottle - of Cygon is reserved for my Dykes Medal tall beardeds.

[plantaholic]

Here's last night's take by the Stinger, on the bottom of a cardboard
box placed on the ground under it:




I have it slung onto a low branch of an apple tree about six feet
away from an iris bed.



Here's an upclose look at a couple of moths it brought in.

I just may be on to a good idea. Will update later on....

[plantaholic]

The Stinger at work. Last night:


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Here's what it brings in:


enlarge

I'm only guessing as to the borer's life cycle, but it appears, judging by the increase in size of some of those moths,
- note that black one in the upper lefthand corner-another week of nightly operation of Stinger is sufficient as a trial on its effectiveness.

[plantaholic]

Here's what last night's take looked like. Kinda looks like Stinger picked
one up.... the one near the center of the picture:


enlarge

I'm looking for this one, or this one.

[plantaholic]

Here's what I found this morning:looks like I got one.


closer look

It looks similar to the one shown here on a Flickr page.

So far my plants look okay, with the exception of some pet-caused damage.

enlarge



Iris borer advice

[plantaholic]

I do believe the adult cycle of macronoctua onusta is over.
This is what the nightly sample looked like throughout the past week.





enlarge

I'll have to wait until next spring to determine if using the Stinger makes a difference.

[Gardentoad]

I check my iris in the spring for signs of borers. I look for wet seepage on dry days. I pinch the leaves together from the bottom up and when I get one I feel a pop. Later in the summer I cut down the browning foliage and trim the tops off and if I find I missed borers I take a stif wire and poke itdown sometimes into the rhizome. If I find a clump in the late summer or fall that I missed borers I dig the clump up, trim down the leaves, cut away any rot and soak the rhizomes (even pieces if there is a sprout on it) in a solution of 10% houshold bleach and 90% water for 15-20 minutes. Then let them air dry a day before replanting.

I don't spray my gardens with anything but neem which doesn't seem to effect iris borers. Chris's method would be a lot easier than mine.

I have noticed that I get more borers where I have several iris planted together. The single iris I have tucked away in mixed perenial beds seldom get infected.

[Aud]

I recently moved and had never had a problem. I moved my Iris from my old house and purchased some. This Spring I noticed some looking wet and because I did not have any experience with this problem I was late catching the problem. I dug them up and the big ugly worms were there. I pulled them out and did what was suggested I hope it is not going to be a on going problem in my new gardens.

[plantaholic]

Please take note of my edited photo: it replaces one which was used in my post preceding it. I wanted to show that the adult (moth cycle) pf the borer had not shown up in over a week. None of the stuff sccumulated by my Stinger resembled the borer moth.

Apologies for any confusion... Yhe main point made is this could be a safe solution. Stay tuned.

[Garden_of_Mu]

Another point their life cycle can be interrupted is early spring before temps hit 70, that is when the eggs hatch and the larvae start looking for iris fans to eat into. The moths lay their eggs on plant debris near irises (not just the irises but nearby plants as well) so doing a very thorough clean up can remove them before they even become a problem.

I'm looking forward to hearing how your experiment with the bug zapper works out for you. Thanks for sharing the results so far.