Treflan, Snapshot and Preen.... opinions please =)

I'm wondering what I can safely use in my bearded iris beds to prevent weeds. Since I'm down south and will already have a moisture problem, I definitely can't use even a thin layer of mulch.... and with all that fertile soil and almost a year round growing season, I can just imagine I'm going to be out there weeding every day if there's nothing there to prevent the weeds from getting started! Has anyone used these products when planting new rhizomes? Does it prevent the irises from thriving? I won't be growing from seed and this is a dedicated iris bed, so there won't be a problem with any other plants.

Opinions? Suggestions for anything else that works? Thanks for the help! =)

I feel silly replying to my own thread after just starting it... but I found a link that discusses pre-emergent and post-emergent treatments for iris beds. Here's the link:

http://pubs.caes.uga.edu/caespubs/pubcd/C867-8.htm

The info is from a horticulturalist at the University of Georgia. Have any of y'all used any of these products listed on the website before? I would love to get some firsthand feedback.

Thanks! =)

Preen is frequently used for pre-emergent weed control in iris beds. I bought a large container of it a couple of years ago, but as soon as I read all of the terrifying warnings on the label, I put it in my garage and haven't touched it since. I have waaaay too many companion animals and wildlife visitors wandering around my iris beds to risk exposing them to such a toxic chemical. I'm not too excited about exposing myself to it, either. At least quack grass and Canada thistles won't kill me.

I use preen regularly around my daylilies and iris and have had no problems.

Thanks for the feedback! =)

LOL! Ev, you probably should have been more specific in your opening query, "I'm wondering what I can safely use in my bearded iris beds to prevent weeds." That depends on whose safety you're concerned with - the irises', yours, or other animals' who may wander through your garden.

Laurie

Laurie, I'm not trying to offend here.... but I guess I was just raised with the opinion that chemicals can be our friends, if used correctly and safely within the label guidelines. My dad's a chemical engineer, our daughter is a researcher in biology and our son will graduate this year with a degree in chemistry. Many a time I've watched a news report that was touting the dangers of this or that and one of them will chime in with comments about the "rest of the story" about the scientific report being blown out of proportion in the news.

True, many people misuse or flat-out abuse chemicals in their gardens, but that is not the case with us. We used organic methods when we lived at a previous house that had acreage, but now we're on a suburban rectangular lot with neighbors all around who do use chemicals. Organic would be impossible here because any beneficial insects we released would soon be killed by their chemical runoff. Other animals (other than pests like squirrels who want to dig!) won't be wandering through the garden as it's a fenced back yard. Our own pets are well-trained and do not enter the garden areas. They have their own preferred spaces well outside the bedding areas.

If we were afraid to correctly use chemicals where they are warranted, within specific guidelines, then we would not be enjoying the abundance of food we have in today's food industry... enough to feed our nation and share abroad. We'd still be dealing with malaria and other crippling diseases because we couldn't control the insects that spread it. The list goes on and on. Granted, a few weeds in my backyard garden will not affect malaria or the world's food supply... but my point is that chemicals are not the enemy... the people who misuse them are.

This message was edited Aug 23, 2008 6:01 PM

I'm not opposed to using the very occasional chemical, but I won't use chemicals that come with as strong label warnings as those on Preen. Same thing with the anti-fungals that are commonly used for leaf spot. I tend to believe label warnings that tell me the chemical can do serious damage to me and mine if extraordinary safety measures aren't taken. That's enough to convince me that a certain chemical isn't worth taking the risk with.

I did use Preen once many years ago, applied it exactly as directed, and immediately watered it in very well. It did not dissolve and disappear into the soil as I'd assumed it would. It sat there on top of the soil for months, causing me significant worry every time one of my animals came near the iris beds. How am I supposed to believe that it's safe for my animals or myself to walk around on a highly toxic chemical just because I watered it in once as directed on the label? If error is to be made, I will err on the side of caution where the health of my family is concerned.

Laurie

Has anyone here used Gallery? The active ingredient is isoxaben... as opposed to trifluralin in Preen. Isoxaben isn't toxic to fish like trifluralin is, and it's labeled as safe around irises. Does anyone have experience with its ability to control weeds?

Thanks for any info!

LOL, I just noticed and thought this was ironic since we're discussing its safety level... the ad banner at the top of the Dave's Garden page at this moment is for Preen!

It sits on top of the soil for months slowly releasing into the soil. That's why I assume that it is effective for 3-4 months before having to re use it again.
I have not noticed any decline of birds, bugs of all sorts or toads in my gardens since using it for almost 2 years now.
I don't even water it in, I just wait for the next rain to do that, I figure why waste water?
On the topic of warning labels, I don't pay them much mind. You never know if they are real warnings, or just the company's way of avoiding a possible lawsuit over any thing under the sun.

There were two preens available when my mother picked up hers....the one she got says it is safe to use around pets etc???

Zhinusmom, your mother probably purchased the new Organic Preen, which is corn gluten. You have to reapply it every month instead of the full season coverage you get with the original Preen with trifluralin. I wouldn't be able to use the Organic Preen down south because it's mode of action is slow release high nitrogen, which suppresses seed germination in the weeds. All the irisarians I've spoken with said that when you have high heat and high humidity, you have to keep the nitrogen level low or your rhizomes will rot... so I couldn't use the gluten. I'm sure in your climate it would be fine. Ev =)

Yeah, and she doesn't have iris either. I just got some from a friend of hers who moved to a retirement home last year, so I am just learning........

The label on Preen or Treflan (used on farms) does not say it is recommended for iris. In my experience and with others here in Minnesota, we have found that especially with first year plantings, Preen doesn't do iris any favors when they are first planted. Growth is slower and sometimes we see the iris blooming on very short bloom stalks. I called up the technical support for a supplier of Treflan and he confirmed the active ingredient is not labeled for use with iris. Also note they have a version of Preen with added fertilizer. I assume this is not just a marketing ploy but may indicate that growth of other plants may also be slowed some by Preen. On the flip side, after my iris are established for a year, we do use Preen on some beds because it does help with some weeds (not thistles, dandelions or quackgrass which drive me nuts). This doesn't seem to retard the iris and it does keep some of the weeds from germinating. I haven't had much luck with mulch, especially peat moss which caused many rhizomes to rot in my garden. So it is just part of growing and enjoying iris for me that I get a lot of exercise through weeding. Also, like Laurief, I try to stay away from the chemicals when I can. In the spring I put a sparing amount of 10-10-10 fertilizer on the iris and Bayer's Merit (imidacloprid) for borer control. When I plant them I try to use a cup or so of alfalfa meal or pellets per rhizome to stimulate root growth and provide some organic fertilization. I think growing iris like many garden flowers requires some effort. For me it is worth it and I have quite a few.
Tim

Irisguy, thanks for the reply. Did you look at my first link posted above, from the University of Georgia? They have Treflan listed as approved for use on irises. Treflan does have irises listed on the MSDS as an appropriate ornamental for trifluralin use (check the MSDS posted online). I have not looked at the MSDS for Preen, so I can't say what is on it. I always check the MSDS of any product before application. Snapshot also has irises listed on the MSDS, and it contains a mixture of trifluralin and isoxaben. I spoke with a southern hybridizer who said he has successfully used Treflan on his iris gardens for many, many years with no ill effects. However, in my research for this, I have come across a few studies that prefer the application of isoxaben by itself (one tradename is Gallery) for spring application and adding Pennant to the application for winter (when unwanted grasses are more of a problem for us here). Isoxaben is not extremely toxic to fish, as trifluralin is, and as we have lots of waterways here in Louisiana, it's the preferred choice by LSU-Ag Extension and others, who have thoroughly tested many of these products for use on both Louisiana and bearded iris.

Users may find this link handy. It's a reference page by Dow AgroSciences for many of their popular products, with direct links to the MSDS sheets and labels:

http://www.cdms.net/manuf/mprod.asp?mp=11&lc=0&ms=3691&manuf=11

Happy gardening!

This message was edited Aug 25, 2008 8:20 AM

P.S. - Actually, it's the specimen label, not the MSDS that I usually check. If you consult the manufacturer's webpage for the products you want, then they will always have the updated specimen label and any additions, which may be listed under separate PDF files.

I haven't noticed any slower growth on my iris since using the Preen. If anything I would think that keeping the weeds at bay would get rid of competition for nutrients, causing the iris to grow faster or at least to make up for the slower growth the Preen *might* cause.
I avoid buying the Preen with fertilizer because I figure I am just paying for expensive fertilizer! Fertilizer can cause the iris to rot also... I rarely fertilize my iris.
I do not mulch my iris either because they tend to rot easily here in MO, hot in the summer and humid, especially this year-rain-rain and more rain!

FrillyLilly, you know... I have noticed that the Missouri weather is very similar to ours here in Louisiana. We've vacationed at Table Rock Lake quite a few times (I LOVE the state park there!!!), and it always seems that it feels JUST like home weather-wise. I've never been there in winter though. I think the difference is that your winters get much colder, so more irises will work for you than would for me. But I'm right there with you that it's hot and humid in the summer there! Thanks for the feedback. Ev =)

Just thought I would put in my two cent's worth as they say. Back when Preen first came out it was made by Eli Lily, and it was part of Lily's Greenfield Garden line. I sold it in my garden center and was really impressed with the whole line. Then the IRS came out with the ruling that no Corp. could have a division that lost money three years out of five. Lily sold it's patent rights to all of it's wonderful products, and my suplyer stopped handeling the line.
My mother was a great iris lover, and started using Preen on her iris. I do not recall that Mother ever wore garden gloves, and she would use the shaker can and would aply a liberal amount right in and around each clump. She did this in the spring right after she did her spring clean up. She did this for as long as our stock lasted. She even claimed that it
kept the iris borers away. Oh yes Mother lived to be 94.
Preen only stops seed from germinating, so it does nothing to stop quack grass, or Canada thistle once it is growing. I did discover Ortho's grass be gone last season. You can spray grass growing even in ground cover and it hurts nothing but the grass. Oh yes, I forgot to say you cannot use Preen on young pansies, as it just stunts the heck out of them. Ron

Thanks for the input, Ron. And definitely a huge thanks for the added info about pansies. We grow Rave Waves in the front bed every fall, winter and spring. They make quite a beautiful and bright show, but summer just shrivels them to bits. No worries though, because the Waves are such heavy feeders, I need that "time out" to rework the beds anyway! I would be so sad if I'd ruined the yearly show with Preen. Ev