Irises forum: BT for Borers (Thuricide)

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Name: DaisyDo
close to Baltimore, MD (Zone 7a)
Irises Cat Lover Plant and/or Seed Trader Organic Gardener
DaisyDo
Apr 24, 2019 6:51 PM CST
Are Arlyn and I the only ones here using BT (Thuricide) on our irises?

This is my first Spring to use it. I've been respraying it after every rain. I swear the iris leaves look more free of borer signs than in past years. Has anyone else here found success with it?

Arlyn said something about avoiding it during bloom, for fear that bees will carry it back to the hive and infect the bee larvae. I probably will avoid that, too, but I'm not sure we need to. From what I've read it only is effective against larvae of moths and butterflies. For example, what I read said that it is not effective against the larvae of sawfly (those little green worms that can quickly defoliate a rose - called rose slugs). It said that because the sawfly is a fly (diptera), its larvae are not true caterpillars and unfazed by BT. Bees, as I recall are hymenoptera, so their larvae would not be true caterpillars, either. So I wonder whether they might be just as unfazed by BT as rose slugs are.

I just hate using insecticides, especially systemcs that get mixed into the soil. My gosh, suppose I sold my house and the next resident decided to plant tomatoes where I had previously planted iris, and basically poisoned the soil with systemic insecticide. I can just imagine the tomato plants sucking up that systemic insecticide and producing fruits loaded with toxic insecticide. Not to mention that any plants planted in soil treated with systemic insecticides are going to produce nectar that is poisonous to the bees and other pollinators.

Would love some input from you all on this.
Name: Arlyn
Whiteside County, Illinois (Zone 5a)
Irises Beekeeper Region: Illinois Celebrating Gardening: 2015
crowrita1
Apr 25, 2019 2:44 PM CST
As to "affecting" the bees.......all I know, after talking to our County Extension agent about it (she also heads up the local "bee keepers group") is that it has showed up in hives, but any detrimental issues with the bees is 'undetermined' Shrug! . We talked a bit about it's possible" use for the "wax moths" that sometimes affect the hives, but, so far...all we've done is "talk" Sticking tongue out .
It's quite surprising what shows up in the "hive studies" that the University has made......besides a whole "batch" of different insecticides, there are several herbicides, and also a couple fungicides. Whether ,or not, any of these things actually HURT the bees, has been a real source of "contention" between farmers, growers, and bee keepers, and I certainly don't claim to know if any ,or all, of them are, or aren't "harmful"....but, I WILL take an 'educated guess" that NONE of them are "beneficial" to the bees, so, I try my best to only use them when the bees are't active...if at all.
As I've said before, IMHO, the absolute BEST borer control measure is keeping the beds clean of dead foliage in the fall.......and burning over the beds does a great job of that,IF your beds are "situated " for it, and burning is "allowed" in your area. Inspecting the plants, as they grow...so any signs of borer damage are caught "right away" is also a "good thing"...if you see some "ragged edges", the old "squish" method is a sure fire way to get 'em !
Name: DaisyDo
close to Baltimore, MD (Zone 7a)
Irises Cat Lover Plant and/or Seed Trader Organic Gardener
DaisyDo
Apr 26, 2019 9:42 PM CST
Yes, Arlyn, for sure! In fact I was out in the garden just yesterday doing the old squish and pop! I don't see many affected irises, but there are a few. It really pays to keep a close watch on them this time of year. I don"t really see how I managed to have any borer at all with my being meticulous about getting every old leaf in the fall as well again in the early spring. It makes me realize how much morse it would be if I weren't doing the fall and early spring clean-ups. I think I read somewhere that California does not have the borer. How lucky they are!
Name: Arlyn
Whiteside County, Illinois (Zone 5a)
Irises Beekeeper Region: Illinois Celebrating Gardening: 2015
crowrita1
Apr 27, 2019 7:23 AM CST
Another thing that seem to work (I haven't done it,, because of 'logistical reasons") is to use those "bug zapper" things in late summer. I know a couple folks (with beds very near a place to "plug in") that place one by each one of their beds, starting about mid-August, so the borer "moths" get "zapped', before they can start laying eggs. They keep them going until it starts 'frosting" Shrug!
I have had very little problem with bores (Knock on wood !) for the last 8 years, or so.....I have seen "minor damage" on a few leaves, and I seem to remember finding one rhizome which was "chewed", but between the "chemical', "biological", "nematodes", and good old "mechanical" (clean-up, and squishing) controls.....I seem to be keeping them in check.
Name: DaisyDo
close to Baltimore, MD (Zone 7a)
Irises Cat Lover Plant and/or Seed Trader Organic Gardener
DaisyDo
Apr 27, 2019 7:40 AM CST
[Last edited by DaisyDo - Apr 27, 2019 7:43 AM (+)]
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