Irises forum: Iris bed disaster

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ngoodman
May 16, 2019 8:51 AM CST
I just stumbled upon this forum and joined. I'm hoping you can help me with some advice. I've had an iris bed in my backyard for a number of years. Almost every year we made it bigger to accommodate my latest purchases! As late as 2017 the bed was a showstopper of beautiful blooms. That fall I added 12-15 new plants.
Last year (after a hard Wisconsin winter and spring) I had only about 5 or 6 blooms. Heartbreak! "Everybody" said it was because of the winter and the flowers will be back next year. The newly planted ones barely made a showing of leaves. Then in the fall, I discovered a few borers 😳 in the bed. We pulled out plants and got rid of the mushy parts, cleaned up debris, etc. This year, my bed looks pretty sparse and sad. I miss the days of all those blooms. Will they ever be back or should I give up on the iris bed? They are my favorite flower. Any thoughts? Thanks!
Name: DaisyDo
close to Baltimore, MD (Zone 7a)
Irises Cat Lover Plant and/or Seed Trader Organic Gardener
DaisyDo
May 16, 2019 10:21 AM CST
When rhizomes become overcrowded, they have a tendency toward borer and rot. And borers promote rot, too..

Every 2 to 3 years you should use a garden fork to lift all the rhizomes, soak them in a mild bleach solution for 10 minutes. Then inspect them for tiny borer holes and rot. Cut out and destroy any affected rhizomes. Replant, spreading them out a bit. I make sure that the ends of the rhizome with active growth always point outward from the center of the clump, so that the center is less likely to become congested quickly. Give them an iris fertilizer early next spring. And next spring consider using either BT or a neem spray, or alterating those, to help kill borers before they get tunnelled in. If they do, and you start seeing streaks on the leaves, start using the squeeze and pop technique.

If you do these things, I think your irises will reward you in future.
Name: DaisyDo
close to Baltimore, MD (Zone 7a)
Irises Cat Lover Plant and/or Seed Trader Organic Gardener
DaisyDo
May 16, 2019 10:32 AM CST
NGoodman, welcome to the Iris Forum! Welcome!
Name: Evelyn
Northern CA (Zone 8a)
Hybridizer Region: United States of America Region: California Annuals Bulbs Butterflies
Cat Lover Foliage Fan Irises Organic Gardener Plant and/or Seed Trader Seed Starter
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evelyninthegarden
May 16, 2019 10:37 AM CST
NGoodman ~ Welcome! to the Iris Forum! Hurray!
"Luck favors the prepared mind." - Thomas Jefferson
Name: Tom
Southern Wisconsin (Zone 5b)
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tveguy3
May 16, 2019 12:15 PM CST
Welcome! ngoodman, nice to see another Wisconsinite join the group. Iris borers lay their eggs in the fall on the iris foliage. If you want to go chemical free, as some do, it's good to always keep the dead leaves pulled off the plants early in the spring, as many of the eggs may be on them. The spent leaves should be burned or put in a bag and taken to the landfill. Don't compost them as they may hatch and come back to haunt you. Some people actually burn their iris beds in the spring, not everyone can do that depending on your situation. It also is possible to see the affected leaves chewed on by the borer, and you can sometimes squash the little bugger inside of the leaf. This of course is not something I can do with over 600 plants. If you are not averse to using chemicals, you can treat your iris beds in the early spring with Bayer Grub killer, the stuff that's made for lawns. Sprinkle it around each plant in the spring before we have a stretch of 5 to 7 days without frost. That's when they hatch. This systemic gets into the plants and as the baby borer starts munching on them they get the poison. It's not too late to do the treatment now if you choose. As for soaking in bleach, besides being very labor intensive, that may kill lots of things, including helpful bacteria that the plant needs to produce food. People have varying views on doing that. Regarding the use of fertilizers, it is a good practice to have your soil tested before you add anything. Just random addition of fertilizers may or may not give your plants what they need including your soil's PH levels. Our ground water supply is already over saturated with nitrates and phosphates, so adding them where they are not needed only exacerbates that issue. That soil test can be done cheaply through your county agents office. Hope this is helpful, and that you have a good year gardening. Smiling
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[Last edited by tveguy3 - May 16, 2019 1:14 PM (+)]
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Name: Bonnie Sojourner
Harris Brake Lake, Arkansas (Zone 7a)
Magnolia zone
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grannysgarden
May 16, 2019 4:02 PM CST
Welcome to the iris forum, ngoodman!

Some very good advice there and I, like Tom, cannot lift and treat each clump so the borer treatment would have to be the way to go. Thumbs up Also, very good advice on fertilizing your plants. Know your pH before you feed. If your soil pH is off the plants cannot take up the food and it runs off into our waterways. Thumbs down good luck.
Rise and shine and give God the glory!!
Name: Robin
Melbourne, Australia (Zone 10b)
Region: Australia Irises Garden Photography Cat Lover Seed Starter
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Totally_Amazing
May 16, 2019 5:02 PM CST
Welcome! ngoodman Hurray!
Name: daphne
san diego county, ca (Zone 10a)
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shizen
May 16, 2019 5:39 PM CST
Welcome! ngoodman. this is a very helpful group and take a look at the other's posts of their blooms. it may help fill the gap, until yours reward you. irises are a pretty hardy bunch. hope you'll be able to save yours from the dreaded borers! Crossing Fingers!
Name: Barbara
Northern CA (Zone 9a)
Region: California Cat Lover Irises Enjoys or suffers hot summers Dog Lover
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iciris
May 16, 2019 6:22 PM CST
Welcome! ngoodman Welcome!
• “Whoever said, ‘Do something right and you won’t have to do it again’ never weeded a garden.” – Anonymous
Name: Scott
Elburn, IL (Zone 5b)
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BlueFlagFan
May 16, 2019 6:25 PM CST
Welcome to the forum, ngoodman! Welcome!
“In every walk with nature, one receives far more than he seeks.” --John Muir (1838-1914)
Name: Lucy
Hamilton, MA (Zone 6b)
irises
Charter ATP Member Cottage Gardener Enjoys or suffers cold winters Region: United Kingdom Region: Northeast US Irises
Region: United States of America
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irisarian
May 16, 2019 9:17 PM CST
Welcome to our forums. Irises should be divided every 3 yeas so it is a good time to check for borers. You might check into using neotobes (check spelling on that) if you don't care for chemicals.
Name: Evelyn
Northern CA (Zone 8a)
Hybridizer Region: United States of America Region: California Annuals Bulbs Butterflies
Cat Lover Foliage Fan Irises Organic Gardener Plant and/or Seed Trader Seed Starter
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evelyninthegarden
May 16, 2019 10:50 PM CST
irisarian said:Welcome to our forums. Irises should be divided every 3 yeas so it is a good time to check for borers. You might check into using neotobes (check spelling on that) if you don't care for chemicals.


Lucy ~ Did you mean nematodes?

https://www.gardensalive.com/p...
"Luck favors the prepared mind." - Thomas Jefferson
Name: Debra
Garland, TX (NE Dallas suburb) (Zone 8a)
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lovemyhouse
May 16, 2019 10:53 PM CST
Welcome! Welcome! Welcome!
It’s okay to not know all the answers.
Name: Arlyn
Whiteside County, Illinois (Zone 5a)
Irises Beekeeper Region: Illinois Celebrating Gardening: 2015
crowrita1
May 17, 2019 6:21 AM CST
Welcome! There has already been some good advice, and tips, so, ll I will do is "second" what Tom said about a soil test, before fertilization.
Name: Lucy
Hamilton, MA (Zone 6b)
irises
Charter ATP Member Cottage Gardener Enjoys or suffers cold winters Region: United Kingdom Region: Northeast US Irises
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irisarian
May 17, 2019 12:14 PM CST
correct Evelyn
Name: Lew
Southern Maryland (Zone 7a)
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LewEm
May 17, 2019 3:21 PM CST
Warm welcome ngoodman Smiling
Name: Deborah
midstate South Carolina (Zone 8a)
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Deebie
May 17, 2019 3:26 PM CST
Another Welcome! Hurray! Hurray!
Name: Lilli
Lundby, Denmark, EU
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IrisLilli
May 22, 2019 11:52 AM CST
Welcome! Hurray!
You don't know if it will grow until you try!
Name: Evelyn
Northern CA (Zone 8a)
Hybridizer Region: United States of America Region: California Annuals Bulbs Butterflies
Cat Lover Foliage Fan Irises Organic Gardener Plant and/or Seed Trader Seed Starter
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evelyninthegarden
May 22, 2019 5:09 PM CST
Welcome! Ngoodman! Hurray!
"Luck favors the prepared mind." - Thomas Jefferson
Name: Sue Petruske
Wisconsin (Zone 5a)
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petruske
Jun 2, 2019 7:27 AM CST
Tom's advise (If you are not averse to using chemicals, you can treat your iris beds in the early spring with Bayer Grub killer, the stuff that's made for lawns) is great advise.

I've been using the Bayer Grub killer for years now. I make sure I apply it before the temperature reaches 70 degrees. That's when the little buggers hatch.

The best way for me to look for borer damage is to pay CLOSE attention to the "center" leaves on the iris fan. That is where the damage begins to be apparent.

I NEVER even heard of the iris borer until a year after extra heavy rains came here in Wisconsin (the kind that washes out roads). I believe that was in 2008??? The following year I started to have a few stalks rot and fall over. I started to research it and dug up an iris...and sure enough there the little bugger was. After getting it under control, I've applied the Bayer product every spring. I still keep an eye out for it. Don't let your guard down.

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