Bearded Iris foliage

This is my first winter with bearded Iris. I used to grow siberian iris which died back to the ground every fall. But this year the bearded iris, which are new to me, have kept their green foliage despite several snow storms and temperatures below minus 10F. The rhizomes were planted at soil level last August.

The foliage has become rather ratty. What is the best approach in spring. Cut back the green foliage ? or simply trim it to remove the dead portions ? What do you do ? and when ?

Since you live in iris borer country, it's advisable to cut off and burn or trash (do NOT compost) all of last year's foliage right down to the rhizome before active growth starts or temps reach 70 degrees, whichever occurs first. That should help eliminate a majority of any borer eggs that overwintered on the foliage.

Laurie

YIKES !!!
Ok, that would be mid april or so, I guess ...

I was planning on putting down Imidacloprid (Merit) to help with borer infestation, but thanks for the advice, nevertheless.

I expect in zone 6b your irises will start spring growth before mid-April. Heck, mine start to break dormancy in April, and I'm in zone 3b.

I, too, use Merit each spring in my iris beds, just as irises are starting growth. It's very effective at borer control, but it's not a substitute for a very thorough garden clean-up before borer eggs hatch (they hatch at 70 degrees). Do both, and you'll have a real leg up on the borers.

Laurie

I clean trim & clean around my iris by the end of March. Late snowstorms & freexes aren't really a problem unless a bud freezes.

Sorry for the dumb question. I've tried to look this up on the net. Can you guys tell me more about merit? I was thinking of using it this year. I don't have a problem using pesticides, per se, but would hate to poison any of the few humming birds that visit. Thanks!

The active ingredient in Merit is imidacloprid, the same active ingredient used in Advantage pet flea control products. It is a systemic insecticide that is taken up by borer larvae as they feed on treated iris plants. I doubt if Merit would have any effect on nectar-feeding birds, but I've never seen any birds, including the hummers, feeding on the irises, anyway.

BTW, you don't have borers there in CA, so you don't have to worry about it.

Laurie

Thanks for the information Laurie. I am so glad we don't have borers in CA! I was going to use it for aphids and scale though. I have lilies that had alot of aphids. Do you think that is an appropriate use? I didn't have much luck last year with using the soap sprays.

They usually recommend imidacloprid for lawns too to combat grubs. This should be safer for other inhabitants such as earthworms who are usually destroyed by other chemicals such as diazinon or trichlorfon.

I have noticed a lack of aphids on my irises since starting to apply Merit each spring. I can't guarantee that has anything to do with the Merit, but if not, it's quite a coincidence.

Laurie

I read somewhere that Merit worked for aphids. So that combined with your lack of aphids experience I think I'll give it a try. The thought of an aphid free yard without having to hassle with daily spraying is so very enticing. Thank you:)

Is this a liquid or granular? Is it available at the big box stores or do you have to go to a garden center.

Merit comes in both granular and liquid forms, though I've read the granular is safer for application to irises. It is generally marketed in lawn grub control products. The one I use is a granular named something like Bayer Advanced Lawn Season Long Grub Control. I apply it once a year in early spring just as the irises are breaking dormancy and starting to grow.

If you use a Merit product other than the one I named above, just make sure it contains *only* Merit (imidacloprid) and no other additives or fertilizers.

Laurie

Laurie,
Since your using it on plants and not grass, do you follow the package directions or do you measure the dosage some other way?

Roseana

I've been using it at a rate of 1 tsp per clump, sprinkled around the clump and watered in. It would probably be better to scratch it in before watering, but I'm too lazy to do that with all my irises. I do, however, sprinkle the tsp. individually around each clump to make sure they're each getting their fair share.

I've applied Merit for the last two consecutive springs. The first year, I didn't find a single sign of borer activity in any bed ... at all. Last year I did find evidence of borer activity in a couple of clumps at the farthest edge of the largest bed bordered by tall grass and weeds. I have since corresponded with a couple of other irisarians who have also noted borer activity at the very edges of their beds, so I think it's particularly important to treat the perimeter plantings carefully with Merit.

Laurie

Thanks Laurie, I didnt remember seeing anything named MERIT. So I will look for the imidacloprid in the ingredient label.

Merit is more a tradename for imidacloprid, but you dont usually find "Merit" sold in stores. Like buying a computer. You may buy a dell computer and the chip inside is "Intel". Intel is just the tradename for whatever you call such a specific chip. I guess makers of insecticides like Bayer could start selling bags with "Merit Inside", but until further most simply put imidacloprid on the lable. Bayer Advanced Lawn Season Long Grub Control is an excellent way to aquire Merit cheaply.

was in garden today with fever chill and all , might as well die some where you love . i have aphids and ladybugs so thick i cant believe it just march 5th .

I tried to find the Bayer's Advanced Lawn Season Long Grub Control at Lowe's today. No luck:( I really want to try it though!

I had to special order my Bayer product through my local feedstore, though I do remember seeing it once several years ago at the local WalMart or KMart (can't remember which).

Laurie

Tazzy,,,we dont want you to go anywhere...but if I gotta..the garden center isnt a bad place..huh ? ! :)