herbicides – The Garden Professors™

Sunday Bloody Sunday

Is this title too extreme? I’ll leave that up to you.

Most of you are aware of the frog controversy that surrounds Round-up. A few years ago a professor from Pittsburgh showed that this chemical can kill aquatic creatures if it gets into a pond. Particularly tadpoles. Not that Round-up is intended to be used around water, but still, it is a concern and I don’t want to minimize it. Nor do I want people to forget that other supposedly safer products have their own set of dangers.

This past Sunday I was in the back yard pulling weeds (there is the possibility that my post last week led to this fate…but I’m not going to examine that here). One of the places where I pulled weeds was under the deck at the back of our house. This area is covered with rock mulch and hasn’t been weeded all year. I started out pulling the large weeds, which took about 15 minutes, and then I started pulling the smaller weeds. After another 15 minutes I realized there was no way that I was going to be able to pull all of the small weeds in what I considered a reasonable time. So I went to the garage where I found a bottle of 20% acetic acid – that super strong weed killing vinegar spray that I’ve mentioned before. I knew the stuff was too strong and not a great choice — I had been planning to take it in to school and use it for some experiments there, but I figured what the heck, it ought to do some damage to the little weeds, even if it doesn’t completely wipe them out. So I started spraying.

The first things I noticed were things that I’ve had to cope with before when using this trigger-spray bottle. The spray misted onto my hand and hit a small cut making further spraying uncomfortable – but I pressed on (At this point you should all be screaming at me PUT SOME DAMN GLOVES ON – You’re right this was a stupid move on my part) and the smell was almost overwhelming. But I expected these things, so I figured I’d finish. Then, out of the corner of my eye I saw something coming from an area that I’d just sprayed — moving across the gravel and approaching fast. It was a small toad, no doubt there to eat slugs. He was hopping all over the place with no apparent direction. Random leaps here and there. I picked him up – and noticed that his eyes were glazed. I called for my wife to bring a bowl of water – which she did. I washed him off, but he had already stopped moving. A few minutes later it was no better – just random twitches and nothing else. His eyes seemed covered by a fine film – almost like cataracts. I put him in a cool moist shady spot hoping that he might get better, but I didn’t have the heart to check on him. The vinegar did him in.

I kill insects and other critters all the time and I’m no vegetarian — so why should I whine about this little guy? Because it’s always a shame when a life is lost without a purpose. This guy was helping me out underneath that deck and I killed him because I made a stupid decision by using a pesticide which I knew was a bad choice. If I’d used Round-up (which I have accidentally sprayed a small amount of on adult toads without apparent effect)– or better yet taken the time to pull the weeds by hand I would have avoided this whole situation and I could have done a better job killing the weeds too.

Spin Cycle

The issue of potential damage to conifers by the turf herbicide Imprelis continues to get a lot of air play in this neck of the woods. One of the interesting things about watching an emerging story such as this is watching some of the sideshows that go on around it and how people spin the issue to match their needs and agenda.

Example 1:

Heritage Lawn Care Company put out flyers in neighborhoods in southeast Michigan with affected trees to promote their service. The flyer incldued the heading “ALERT:DYING PINE AND SPURCE [sic] TREES” The flyer claimed that issues related to Imprelis damage to trees are “99.9% applicator and mixing errors”. Surprisingly, there was no mention of where they got the data for this assertion. But fortunately Heritage stands ready to save the day by using “only organic based fertilizers giving the same or better results”. Again, no mention of how organic fertilizer controls tough weeds like ground ivy and wild violet. Thankfully, “If you prepaid (your lawn care provider) for 2011, and want to switch companies, Hertitage is willing to extend you credit until your current company refunds your money.” Call it a hunch, but I don’t think the folks at Heritage will be receiving an invitation to the local landscaper’s group picnic this year…

Example 2:

Mother Earth News trumpeted the news on Imprelis with the headline “Imprelis: Another Deadly Herbicide, This Time From DuPont” http://www.motherearthnews.com/grow-it/imprelis-killer-compost-zb0z11zrog.aspx First of all, isn’t ‘Deadly Herbicide’ redundant? Every ‘icide’ is designed to kill something so I think they’re supposed to be deadly, at least on their target. While the unintended damage to spruces and pines is certainly unsettling, especially for a newly released product, this group of herbicides has low toxicity to mammals and in many regards is comparatively safe. I don’t consider myself a nozzlehead but I’m sure most GP readers recognize I have little aversion to judicious use of chemicals around Daisy Hill farm. So I was a little taken aback to find my “Fasten your seatbelt folks, this could be a bumpy ride” (GP Blog 6/27/11) quoted in Mother Earth news. My reference was to applicators having to deal with customer complaints and potential litigation – but that’s the nature of putting things into the blogosphere…

Example 3:

On July 14 I received an e-mail advertisement from Growth Products, Inc. breathlessly announcing “An Essential Cure For Trees Damaged By Imprelis Or Sahara Herbicides.” Pretty impressive stuff: We’ve only known about the issue for three weeks and these guys have already found the cure. I had to read on. The cure consists of an “Essential Cocktail” of three Growth Products liquids including Essential Plus (a rich concentration of organic ingredients including humic acid), Micrel Total (“Eight chelated minors to help the tree through stress”) and Companion (a biological fungicide). Alas, once again eye of newt and wing of bat were apparently out of stock. But, “The magic mix can be used as a soil drench and/or a soil injection.” The e-mail also included a link to an article I wrote for our extension news that included a photo of some maple trees that had largely recovered from herbicide injury by Sahara in 2009. I also documented the case here on the GP blog I wasn’t aware, but apparently a landscaper treated the trees with some of these concoctions. No word in the e-mail from Growth Products on how the untreated control trees did.

Imprelis update

I’ve been continuing to track some of the reports of injury to conifers associated with the new herbicide, Imprelis. Interest in the problem is likely to escalate given a front page article in the Sunday’s Detroit FreePress. http://www.freep.com/article/20110710/NEWS06/107100467/New-lawn-chemical-chief-suspect-mysterious-deaths-trees

I visited about ten sites last week with an applicator that had used Imprelis this spring. The landscaper was a certified applicator with about 15 years of experience with herbicides, insecticides and fungicides, who was knowledgeable about his chemicals and plants. We saw bout 50 trees, mostly pines and spruces with varying levels of injury. The typical symptoms were brown or off-color needles, and stunted or twisted shoots. Damage was mostly limited to the current flush of growth, resulting in a distinctive pattern of growth. In many cases, there was evidence of spiral movement up the trunk of the tree. The most rapid growing points (usually terminal leaders) were most severely affected. Based on my experience with other forms of herbicide injury and other types of environmental damage, I suspect all but the most severely injured trees would recover is given enough time and some corrective pruning. The problem, of course, is that most homeowners don’t want to wait around while the tree in their yard tries to rally.

Some photographic ‘highlights’

The $64 question now becomes, “What happened?” In order to receive registration from the US EPA, each new herbicide has to go through extensive testing. According to DuPont, over 400 tests were conducted with Imprelis. Despite some claims elsewhere on the internet, this testing included independent university trials on spruces and pines at up to 4x the labeled rate. The key to unlocking the mystery of Imprelis injury will probably lie in understanding how conditions in actual application conditions differed from the testing.

Imprelis damage to landscape conifers

Herbicide issues seem to be dominating my life these days. Over the past several weeks reports have surfaced around the Midwest of landscape conifers – primarily spruces and pines – that have developed rapid and severe die-back. While there are a host of insect pests and pathogens that can cause die-back in conifers, the recent cases are noteworthy in the speed with which trees expressed symptoms.

Photos: Andy and Carol Duvall

In many cases that have been reported the common thread appears to be the use of Imprelis, a turf herbicide developed and marketed by Dupont. Imprelis (active ingredient: aminocyclopyrachlor) is a synthetic auxin designed to control broadleaved weeds in turf. Ostensibly, one of the advantages of Imprelis is that has root activity in addition to foliar activity. It appears, however, that it may have too much root activity and the internet is abuzz with photos and posts of Imprelis-damaged conifers. http://bestlawn.info/northern/imprelis-and-dupont-trouble-t4608.html

http://www.buckandsons.com/blog/tag/dupont-herbicide-imprelis/

So what’s going on? Well there are lots of blurbs coming out and lots of things being reported second and third-hand. I suspect a few things we ‘know’ about Imprelis right now will turn out not to be the case in a few months. Dupont has tried to shift blame to the applicators, suggesting that their rates may have been off, they applied when there was potential for drift, or that the material was mixed with other herbicides. http://www.ksuturf.org/blog/wp-content/uploads/2011/06/DuPont-Letter-to-Turf-Professionals-061511.jpg

Given that reports of damage showing similar symptoms have come from Kansas, Iowa, Indiana, Michigan, and Ohio it seems unlikely that everyone is mis-applying the product. I suspect one of a couple things may be going on. Dupont may have underestimated the lateral extent of tree roots, especially for conifers that often have shallow, extensive root systems. It’s also possible that Norway spruce and white pine are more sensitive to this product than whatever Dupont tested it on.

In the meantime stay tuned. In case people haven’t figured it out for themselves, Dupont now recommends that applicators not use Imprelis near spruces or pines (see letter linked above). Landscapers or lawn service operators that have applied Imprelis should keep in touch with their state Department of Agriculture and their professional turf and landscape association. Might be good to fasten your seatbelts, this could be a bumpy ride…

Read and follow label directions…

Every extension specialist or educator that mentions any kind of pesticide in a talk or article always includes the disclaimer ‘Read and follow all label directions.” However that caveat ranks somewhere between “Your seat cushion may be used as a flotation device” and “Do not remove tag under penalty of law” as the most ignored phrase in the English language. While we can probably rationalize ignoring the last two (If a jetliner ditches in the middle of the Atlantic is a seat cushion really going to save you? And when was the last time you saw someone led away in handcuffs for pulling the tag off a mattress?); failing to pay attention to pesticide labels can have some real and immediate consequences.

I got called recently to inspect some tree and shrub damage at an industrial park in suburban Detroit. (Because the case potentially involves some legal issues, I won’t mention names of any parties). The industrial park included several hundred acres, much of it turf and landscape beds of trees and shrubs. The park had its own groundskeeper but contracted out its spray applications. A couple summer’s ago the staff groundskeeper complained several times to the contractor that they weren’t doing a sufficient job of keeping up with the weeds in the landscape beds. The typical vegetation management tools of choice on this site were spot applications of Round-up (glyphosate) and hand-weeding. For reasons that are not completely clear, this time the contract applicator reached for a jug of Sahara. Even if you don’t know what Sahara is; what image does the name conjure up? Parched. Barren. Lifeless. Sahara is a combination of two herbicides (Diuron and Imazapyr) designed for complete vegetation control in non-cropland areas such as parking lots and rights of way. And, unlike Round-up, Sahara provides foliar and root activity. This is a product you use when you want complete burn-down and you don’t want anything growing there for a long time.

A hedge maple 2 years after herbicide application

Unfortunately, that was not the desired result in this location. Within a week of the application, dozens of trees and shrubs all over the industrial park were either dead or wishing they were dead. The smoking gun was not too hard to find. The applicators had duly noted the herbicide application in their logbook and presence of active ingredient was confirmed in soil samples. Although the parties are still working a settlement, the bids for replacing the affected trees and shrubs are well into six figures.

The unkindest cut of all. These green ash were regularly treated with imidacloprid to protect against emerald ash borer. An herbicide ap took them out instead.

Two years after application there are still bare zones where Sahara ran off from mulch rings and landscape beds.

Of course, all of this death and destruction (and legal wrangling) could have been avoided simply by… Reading and following the label directions. The Sahara label notes in several places that contact with roots can damage trees and other plants, including this explicit statement under a heading in all bold letters, PRECAUTIONS FOR AVOIDING INJURY TO NONTARGET PLANTS: “Injury or loss or desirable trees may result if Sahara is applied on or near desirable trees or on areas where their roots extend.” Sounds pretty clear to me folks – don’t use this stuff near plants unless you want them to die.

So, next time you or someone working for you has any question about what a pesticide does: Read and follow label directions….

Sudden Death Syndrome in Soy — Biggest Threat to the Entire Food Chain?

This past week we received an interesting e-mail about something called “sudden death syndrome” which we were asked to blog about. Here’s the article we were sent. We don’t always take requests, but we thought that this was an interesting one, so we decided to write a little post about it. Sudden death syndrome is basically a fungal disease which affects the roots of soybeans. Recently there has been some press out there about how Round-up ready soybeans are particularly susceptible to this disease and that the spraying of roundup itself can lead to favorable environments for it.

This is a particularly attractive disease for a number of groups because it provides fuel to their fire. The anti-biotech group likes it because it makes Round-up ready crops look bad, the anti-pesticide group likes it because it makes pesticides look bad, the anti-Big Ag group likes it because it makes Monsanto look even more evil than usual. So, in short, lots of happily indignant people.

So is it true? Is using Round-up and Round-up Ready Soybeans a sure way to condemn ourselves to a soyless future? On a side note this is something I really care about – I am a chronic soy sauce user. If something is good without soy sauce it then it is going to be even better with it. Well, I spend most of Monday and Tuesday looking through scientific articles and here, in a nutshell, is what I came up with:

Sudden death Syndrome is certainly real, and it can devastate a field. It was around before Round-up and it will be here after Round-up is gone. The biggest factor in whether it will be a bad year for SDS is the weather. So what about the Round-up connection? This is something that has been looked at by researchers, and here’s what they find. In terms of the fungus responding well to Round-up – some studies show that it does – most that it doesn’t. Round-up Ready varieties of soybean may be resistant or non-resistant to SDS and, of course, the non-resistant varieties won’t fare as well as the resistant varieties if SDS is present (it seems possible that this is where the whole hullabaloo started — a field full of Round-up Ready soy but which wasn’t resistant to SDS contracted the disease while nearby non-Round-up Ready soy which did happen to be resistant to SDS did fine.)

Now there are some studies, mostly in test-tubes and greenhouses, which show that Round-up could make SDS worse, but in the field, where it actually matters, there just aren’t that many studies which show a correlation between using Round-up Ready soybeans and SDS — and more studies that show that there isn’t a correlation. What it all comes down to is that there is a possible relationship between Roundup and SDS, but, despite a lot of research (both government and industry dollars flow easily to agronomic crops), this link isn’t crystal clear and may not exist at all.

Dandelions and clover

It was fun to read all of your comments last week about your opinions on lawn care. To follow up on it I’m going to talk a little bit about why I’m not fond of companies which apply herbicides multiple times throughout the year. But first I think I’ll mention why I apply herbicides at all — aesthetics. That’s it — the whole reason. Could I go the no-lawn route? Yes, but I like having a yard to run in. Not a huge yard, but a little yard to play tag with the kids.

What I long for though is the yard from the house that I grew up in. Our house in southeastern PA (About an hour west of Philly and an hour east of Lancaster) was set back about 800 feet from the road and was on old agricultural land. The area around the house was planted in grass in the mid 70s and then it was left alone. Fertilized once the first year I think, but that’s it. Dandelions invaded quickly as did clover. Over the years the clover began to dominate the grass, but not to the point that the grass disappeared, and the lawn actually appeared relatively homogeneous. Dandelions never left, but their numbers declined. The clover grew low and the grass never shot up like it does in a heavily fertilized lawn and so mowings only happened once every two weeks or so (well, OK, sometimes more often depending on the weather and where on the lawn you were — the spot over the septic tank needed mowing every 48 hours or so). The grass did go dormant most summers, but 800 feet from the road there wasn’t anyone to complain, and besides, the clover kept the lawn from appearing completely scorched. The lawn looked good for well over 30 years (until my parents remodeled the house and the yard was torn up).

The typical suburbanite might not have liked this lawn, but to me this lawn looked great, and, besides, it was low maintenance. The reason I’m bothering to tell you about this lawn though is because it illustrates so well what lawn care companies make impossible. They say (and by “they” I mean professors like myself) that pesticides beget pesticides and fertilizers beget fertilizers, and nowhere is that as true as in a well manicured lawn. The herbicide of choice is 2,4 D (though there are many others that are used) which lawn care companies apply multiple times over the the course of a year. This pesticide does a great job of killing dandelions, but it also kills clover. It rarely hurts grass unless it’s grossly over-applied. The problem with killing clover is that this clover is the stuff that fed the grass in the house where I grew up. Clover takes nitrogen out of the air and makes it available to grass every time the lawn is mowed (the clipped off pieces of clover degrade and the nitrogen in them feeds whatever plants are around). Without the clover you need to add fertilizers. So, because the lawn care company is keeping the lawn free of weeds they also need to fertilize because they’re killing all of the natural fertilizer. Here’s the thing, the weed that most people in the suburbs like least, dandelions, is actually very sensitive to low potassium. The lower the potassium in the soil the worse it does. In fact, dandelions can easily be out-competed by grass and clover if potassium is low — just as happened in the yard of the house where I grew up. But do lawn care companies pay attention to this (by using high nitrogen, low potassium fertilizers?) What do you think?

My guess is that many of you thought that I’d cite all kinds of scary side effects of the pesticides used on lawns. Nope. In general I think that, if used properly, they’re pretty safe for humans (with a few notable exceptions). I’ve spent a lot of time reviewing epidemiological and toxicology studies and I can think of many worse things. I am somewhat fearful of what 2,4 D may do to dogs in particular — they can’t excrete this poison like we can. Don’t think for a minute that I’m calling these poisons perfectly safe — I just think there are plenty of other better established reasons to avoid lawn care company pesticide schedules.