pesticide – The Garden Professors™

Spec errors mount

For years I subscribed to Consumer Reports. I appreciated their objective approach to product testing and lack of advertising. In their own words, their policy is to “maintain our independence and impartiality… [so that] CU has no agenda other than the interests of consumers.” But recently they’ve veered off the science-based trail – at least the one running through our gardens. Their approach to plant and soil sciences is more pseudo than science. And last year, after 30+ years of loyal membership, I quit my subscription when Consumer Reports began partnering with Dr. Oz (see here for instance ).

So until today I’ve been blissfully unaware of whatever CR has published on gardening and garden products. Then this post appeared on our Garden Professors blog group page ). I’ve included some of the article below along with my italicized comments in brackets.

“Lawn care without the chemicals: rid your yard of weeds and pests with these mostly organic solutions”
“…Here are 10 common weeds and pests that plague homeowners nationwide, along with chemical-free measures [“chemical-free?” Well, we shall see.] that should be effective in bringing them under control. For more information, go to the websites of Beyond Pesticides and the Great Healthy Yard Project. [Neither of these two sites is remotely scientific or objective.]

“Dandelion – what is it? A perennial weed whose common yellow flowers turn to windblown seed. Telltale signs. Though a handful of dandelions is no big deal, a lawn that’s ablaze in yellow has underlying problems that need to be addressed. How to treat. Like many broadleaf weeds, dandelions prefer compacted soil, so going over the lawn with a core aerator (available for rent at home centers) might eradicate them. [Like many broadleaf weeds, dandelions will grow anywhere. That’s why they’re called weeds.] It also helps to correct soil imbalances, especially low calcium.” [I’m curious how CR determined a “soil imbalance.” And did they test their hypothesis experimentally?]

Dandelions obviously suffering in a calcium rich soil

“Barberry – what is it? An invasive shrub with green leaves and yellow flowers, often found in yards near wooded areas. Telltale signs. Left unchecked, the shrub’s dense thickets will start to choke off native trees and plants. How to treat. Cut back the stems and paint their tips with horticultural vinegar or clove oil (repeated -applications may be needed). Burning the tips with a weed torch might also work.” [Yes! Chemical free vinegar and clove oil! By the way, clove oil has NO demonstrated efficacy for this application. And I’m sorry, but “burning the tips” of barberry is just going to stimulate lots of new growth below the damage. Just out of curiosity, how many people have problems with barberry in their lawn?]

I think you’d notice this in your lawn…

“Crabgrass – what is it? An annual weed with a spreading growth habit. It’s common in the Northeast, in lawns with poor soil conditions. Telltale signs. Lots of bald spots, especially after the first freeze, when crabgrass dies off. How to treat. Have your soil tested. Lime or sulfur may be needed to adjust the pH. Aeration is also recommended. Corn-gluten meal, applied in early spring, can be an effective natural pre-emergent herbicide. [Corn gluten meal, applied in early spring in climates where it rains, is an effective fertilizer for crab grass.]

Crabgrass with increasing levels of corn gluten meal.
Courtesy of Tom Cook, Oregon State University.

“Kudzu – what is it? An aggressive climbing vine that’s common in parts of the Southeast and the Midwest. Telltale signs. The thick vine forms a canopy over trees and shrubs, killing them by blocking out sunlight. How to treat. Pull out the vine and, if possible, its taproot. Be sure to bag and destroy the plant or its vines will regerminate. If the root is too thick, paint the stump with horticultural vinegar or clove oil repeatedly, or burn it with a weed torch.” [Ditto the comments for barberry.]

Have fun painting stumps. (Wikimedia)

“Canadian Thistle – what is it? An aggressive creeping perennial weed that’s found throughout the U.S. Telltale signs. Look for outbreaks in vegetable gardens, particularly those with peas and beans. [I have no idea where this little nugget of nonsense came from. It’s a weed! It will grow ANYWHERE! It doesn’t need peas and beans!] How to treat. Repeated hand weeding and tilling of the soil will weaken its extensive root system. [Because tilling the soil is such a great way of suppressing weed seed germination. And it’s really good for your lawn, too.] Planting competitive crops, such as alfalfa and forage grasses, will keep it from returning.” [Yes, do replace your lawn with alfalfa and forage grasses.]

Your new, improved lawn (Wikimedia)

“Fig Buttercup – what is it? A perennial weed with yellow flowers and shiny, dark green leaves. It’s common in many parts of the East, Midwest, and Pacific Northwest. Telltale signs. The weed will start to crowd out other spring-flowering plants. It can also spread rapidly over a lawn, forming a solid blanket in place of your turfgrass. How to treat. Remove small infestations by hand, taking up the entire plant and tubers. For larger outbreaks, apply lemongrass oil or horticultural vinegar once per week when the weeds first emerge. It might take up to six weeks to eradicate.” [Now in addition to pouring vinegar on your lawn, we’ll try lemongrass oil instead of clove oil. Another unsubstantiated application – maybe lemongrass because buttercups are yellow? Makes about as much sense as anything else. It smells nice though.]

Color coordinated weed control

“Phragmites – what is it? An invasive grass species found nationwide, especially in coastal wetlands [where so many of us have lawns]. Telltale signs. Dense weeds can crowd out other plant species without providing value to wildlife. How to treat. Cut back the stalks and cover the area with clear plastic tarps, a process known as solarizing. Then replant the area with native grasses.” [Solarizing pretty much nukes everything that’s covered – not just the weeds. In fact, the rhizomes of this weed are so pernicious I’m not sure that solarization would work. Am still waiting for CR to test their hypothesis in an objective and scientific manner.]

Phragmites rhizome (Wikimedia)

So, Consumer Reports, I’d love to come back to you. But until you start applying your own standard of objective rigor to everything you cover, I’ll have to pass.

Shooting Fish in a Barrel

Someone recently posted a scientific article on our Facebook page which purportedly demonstrates that Roundup can be damaging to earthworms at concentrations that would typically be used in a field situation. Wow. Scary. I mean really, if we’re damaging earthworms when we apply Roundup, then that lends fuel to the emotional fires that rage against this pesticide. But is that really what this article shows?

It’s unfortunate, but most of you will not be able to see the article that I’m writing about because you won’t have access to the journal in which it was published. Here’s the abstract though.

http://link.springer.com/article/10.1007/s11270-014-2207-3

Basically what the authors did was to place worms in small pots, expose the pots to different concentrations of a commercial formulation of Roundup, and measure how the worms fared over time (about a month and a half). Unsurprisingly, the worms not exposed to Roundup performed better than the worms exposed to the Roundup.

After reading the above paragraph you might think that this is an open and shut case. Roundup is bad for worms, potentially leading to “local extinction” of these animals in agricultural fields (that’s the authors’ wording).

It’s not that simple. The authors are stretching well beyond the data, and the research has some issues, most of which could be cleared up by better, more thorough reporting.

First, let’s take a look at some of the problems that this paper has in terms of reporting its materials and methods. You may think this is picky, but it’s not. It’s fundamental to figuring out how valid the reported results are. From the materials and methods as they were written it is impossible to figure out exactly what was done in terms of watering the pots (we know soil moisture was kept at 80%, but we don’t know how. Watering? With what?). We don’t know what the ground plant materials were that were added to the pots (Lima beans?). We know that pots were placed into 1m X 1m X 0.60 m containers, but we don’t know how many pots were placed into each container or whether pots were randomized by treatment within each container. Sure, we could make assumptions – but in a well written scientific paper we shouldn’t have to. Would knowing these things affect how the worms performed in the Roundup treatment versus the no Roundup treatment? In a word, yes. The watering regime in particular might very well alter the results of this study.

That’s enough of that. Now let’s take a look at my BIG PROBLEM with this study. Six worms were placed into small (28cm X 14cm), half-filled pots and treated, or not treated, with Roundup.

Let me offer an extreme analogy to explain why this is such a problem. Let’s say that you want to see whether shooting bullets into the ocean will kill all of the fish that live there. To test the theory you grab a 50 pound fish and you stick it in a 5 gallon bucket. The tail is hanging out, the fins are flapping, water is getting all over the place. Then you shoot the bucket. Dead fish. You do this 50 more times. Each time, dead fish. You conclude that shooting bullets into the ocean is indeed a threat to fish and may lead to local extinction. Right?

Wrong.

From this study you can conclude that bullets can kill fish. That’s an easy conclusion to make. You cannot conclude that shooting bullets into the ocean will kill all the fish there. Now, if we hired a swat team to fire bullets into the ocean and all the fish were killed, well then we could make that conclusion. Would that actually happen though? No way of knowing unless we try it. I suspect the ocean would retain its fish – but I’m just hypothesizing. (Quick FYI – high velocity bullets lose so much of their speed when they hit water that they wouldn’t be lethal to fish after traveling about 3-4 feet).

There are any number of studies out there that FORCE target organisms to be exposed to whatever chemical is being tested (that is basically what is being done here). These studies CAN show that the chemicals tested MAY affect the target organism. They CANNOT show that the target organism IS AFFECTED IN A GIVEN ENVIRONMENT. You need to test the chemical in that environment to figure that out.

To give an example of how you might test the effects of Roundup against worms in an agricultural environment: Take an acre of agricultural field, divide it into six sections. Treat three with Roundup and control weeds in the other three sections with hand weeding. Sample the sections every two or three weeks after Roundup application to see how the worms are doing.

Now, my final problems with this paper. Much of it is related to other, already published studies. This, in and of itself, is no problem. It is good that there are many studies on this topic. The problem is that most of these studies weren’t mentioned in this article. When I read a scientific article I count on its authors to put their study into context for me so that I can see where it belongs in the already existing collection of related literature. Without referencing these older papers the authors do us a disservice. I’m not going to list out all of the studies, but if you go to scholar.google.com and type in earthworm and glyphosate you’ll see what I mean.

I believe that any experiment from which data can be extracted should be published. I think that the authors of this article had every right to publish it. However, as a scientist, I think that there are enough problems with the reporting of this article, particularly the materials and methods, that, as it is currently presented, I can’t extract much of value. I certainly can’t reach the sweeping conclusions that its authors do.

Organic insecticides that will get you high

Plants are crazy chemical factories, synthesizing a whole host of compounds that we use for flavoring and dye and medicine and… getting high. And why are they making all these chemicals? They’re certainly aren’t doing it for our sake… no, quite often they’re trying to kill something – usually insects — and it just so happens that sometimes our brains and bodies react differently enough that instead of killing us, they make us high. Well, and sometimes they kill us too.

Nicotine, the addictive force behind cigarettes, is a potent natural insecticide. if you’ve heard of neonicotinoids, the pesticides that some are concerned with in relation to honey bee health, they’re synthetic insectides based on the chemistry of nicotine, and like it, they effectively kill insects. No word on if anyone has tried smoking them yet.

Opium poppies are full of a thick latex loaded with chemicals like morphine and codeine, to name a few, which are obviously used as pain killers, and of course opium is taken directly or processed into more potent forms like heroin. The research on these chemicals indicates multiple possible functions, acting to prevent damage by herbivores (like insects), and possibly also acting to prevent pathogen damage and maybe even a more structural function in strengthening cell walls in response to damage (see: http://pubs.acs.org/doi/abs/10.1021/np020583l) I didn’t find any research looking directly at opium’s ability to kill insect pests. Probably because that type of research is usually aimed at a practical solution to pest problems, and even if heroin proves to be a potent insecticide, I doubt anyone would issue and extension bulletin recommending you use it to control your whitefly…

But that lack of practical application didn’t stop a researcher from publishing a paper titled Cocaine as a Naturally Occurring Pesticide in which they found that cocaine was highly effective in killing tomato hornworm! Organic growers, take note! Maybe THAT’S why organic tomatoes are so expensive at the farmers market…

In any case, it is fascinating to note all the interesting, sometimes useful, often dangerous chemicals that have evolved thanks to the on-going chemical arms race between plants and the things that try to eat them. We’re the accidental beneficiaries – and sometimes victims – of that very, very old battle.

Applying pesticides when you don’t mean to

I’d rather we didn’t use them, but I see their value and I appreciate what they can do for us when they’re used properly. One of the things that I hate about pesticides though is that, even when they’re used correctly, sometimes they can come back and hurt us in ways that we don’t expect. You have probably heard that you should not use grass clippings where herbicides have recently been used as a mulch because they could injure them. This is mostly because of the pesticide 2,4 D and other, similar herbicides for the lawn which can injure other plants if placed in the wrong spot.

Back in 2011 the herbicide Imprelis was used on many yards, especially in the Midwest, and did a lot of damage to spruce and other trees as Bert has mentioned in previous posts. We had thought that we were nearing the end of the effects that this herbicide would have, but now I’m not so certain (see Bert’s post from March 25). Recently questions have been asked about whether this stuff might last longer than we thought in compost. A few months ago I probably would have said that I doubted that Imprelis would linger long in compost, but, in part because of how long its effects take to show up on some plants, now I’m not so sure, and there are others who share my concerns (in fact, it was these guys who pointed out the possibility of compost problems with Imprelis to me). I honestly don’t know whether compost that includes trees that were treated with Imprelis (or has Imprelis in it for some other reason) would or wouldn’t be harmful to other plants, but I do know that it’s something I’d be watching out for.

Important, must-read announcement regarding pesticide use

There’s a new report out from the Weed Science Society of America (WSSA) which blasts a common piece of gardening advice: use least toxic pesticides only as a last resort. Popular as it may be, this advice is not scientifically grounded and can actually cause more harm than good. The WSSA is joined in this announcement by the American Phytopathological Society (APS) and the Plant-Insect Ecosystems Section of the Entomological Society of
America (P-IE ESA).

This is a must-read for anyone who is a responsible educator regarding pesticide use, which includes Master Gardeners and other horticulture paraprofessionals. You’ll want to use the webpage link above to read the entire announcement, but here’s a paragraph to get you thinking:

“There is no benefit or scientific basis to simplistic messages like “use least toxic pesticides as a last resort” for the large number of pesticide users who apply pesticides according to the label and practice good stewardship. Nor are these messages beneficial for those who neither seek training nor adequately read the label believing instead that it is safe, practical, and effective to simply choose a product considered a “least toxic pesticide” and apply it only as a “last resort.” These messages hinder pesticide safety and stewardship education and practices that are in the best interest of the pesticide user, our food supply, public health and ecosystem preservation.”

New study on pesticide use and GMOs

Some environmental extremists discount agricultural research done by universities, because they receive funding from Big Ag and therefore their researchers can’t be trusted. So this news report of a recent study by one of my Washington State University colleagues is doubly important: it dispells this baseless assertion and it provides some significant – and troubling – information about pesticide use and GMO crops.

Briefly, the article links an increased use of herbicides as a result of increased use of GMOs such as Roundup-ready crops. Weeds build up resistance to herbicides over time, meaning that Roundup becomes less useful as a weed killer and farmers have to turn to more toxic substitutes like 2,4-D to control weeds.

Dr. Benbrooks’s results, published in a peer-reviewed journal, are contested by the chemical industry, and other scientists question the seriousness of the problem. But next time you hear someone malign university scientists as being in Monsanto’s back pocket, please refer them to this post.

So…How Much Pesticide Is Actually In Our Fruits and Veggies?

We have discussed the dirty dozen here before – those foods which a group called The Environmental Working Group (wow—fancy name – everything they say must be true!) has established contain more residues of different pesticides than other foods. I’ve already stated my concerns about selecting organic foods instead of conventionally grown ones because of a fear of pesticides so I won’t restate that here. Instead what I want to call your attention to an article sent to me by our visiting professor, Charlie Rowher. This article runs down the amounts of pesticides that are actually in the dirty dozen. And the thing is….there just isn’t much pesticide of any sort on most foods and there is no evidence at all that eating these levels of pesticides would be bad for us in any way – even if we ate them in copious amounts day after day.

To be honest I think the authors of this article go a little too far – I do think that there is some potential for damage even from the ultra-small pesticide doses that we find on our foods. But their points are well taken – the amount of pesticides in food is miniscule and less likely to be damaging to us than a great host of other things. I’m much more concerned about certain segments of our population suffering malnutrition from avoiding conventionally grown fruits and veggies than I am about the larger portion of our population getting cancer from eating them.

Bees and Pesticides

I had the opportunity to read a disturbing post over at Garden Rant the other day about the insecticide clothianidin and how the EPA required its producer, Bayer, to run tests on the safety of using plants grown from seeds treated with clothianidin for bees. Tests which were, apparently, never carried out appropriately. This post sent me over to another site, AlterNet, which explained the problem in detail. In a nutshell what happened is that the EPA asked Bayer to run some tests on how its new pesticide might affect bees. Bayer was unresponsive at first, but eventually did run some tests (which were not what you would call robust) which showed that bees did fine when flitting around in a field of plants which came from clothianidin treated seeds – at least for as long as the test was carried out.

Then one of our commenters asked for our opinion, and heaven knows, I am always more than happy to offer my personal opinion! So here it is. I am extremely unhappy with both Bayer and the EPA in this instance. They didn’t do what they were supposed to do. It’s as simple as that. Tests were supposed to be run to demonstrate that it is unlikely that clothianidin affects bees. This wasn’t done in a reasonable period of time. Period. As long as stuff like this occurs nobody is going to trust the EPA or the chemical manufacturers. In terms of whether the tests were sufficient (basically some hives in a field of treated plants), well, I would have liked to have seen more depth, but they didn’t seem to be bad studies.

The implication is that, because we don’t have enough testing, clothianidin could be causing bee colonies to collapse. This goes hand in hand with the suspicion that imidacloprid is leading to colony collapse since both of these chemicals are neonicotinoids. We know that these pesticides can get into flowers where bees come into contact with them. The question is whether the bees contact enough to cause hives to collapse (There is no question that these chemicals, at some level, are poisonous to bees – just as almost anything can be poisonous to humans at a high enough dose – even water).

One thing that is lost in this discussion is that SEED TREATMENTS were being examined. A seed treatment is when the seeds which are planted are treated with a pesticide (in this case clothianidin) to protect the seed itself and the young plant from insects. As the plant grows the insecticide will break down and become diluted – And so it is probably not going to be present at high levels in pollen that the plant (which comes from the treated seed) produces. Still, there is potential for this to happen and so it is best if the plants which come from the seed are tested – hence the EPA’s request.

Historically, there are pesticides which have clearly and unambiguously lain waste to bee hives, the most infamous of which was Penncap-M. This was a unique pesticide because it was a microencapsulation of the very dangerous insecticide methyl parathion. The microencapsulation process made this pesticide last longer, and made it somewhat safer to handle, but it also made the pesticide into tiny little beads – about the same size as, you guessed it, pollen. In fruit trees in particular this stuff would become attached to the bees (just like pollen does) and you can imagine the disastrous results. The answer was to limit the use of this poison to certain times of the year and certain situations when bees were not likely to be around. Why wasn’t it just banned outright? Because it worked well and, when used appropriately, it didn’t affect bees (Here I’m giving you the official line – In my opinion its use should have been even more restricted than it was). Penncap-M is not closely related to the neonicotinoids chemically, though it does affect insects’ nervous systems as many insecticides, including the neonicotinoids, do.

You can count me as one of the people who suspect that the neonicotinoids have something to do with colony collapse. I’m not a bee researcher — but it is easy to see how the use of these chemicals might weaken a hive to the point where mites or disease could come in. One of the things that drives me a little nuts though are those people who think that banning neonicotinoids is going to save our bees. It seems quite obvious at this point that these chemicals are definitely not the sole cause of the disease and perhaps not even one of the major contributing factors. They essentially banned these pesticides in parts of Europe, and guess what? They still have bee colonies collapsing. An interesting side note is that historically large-scale losses of bees isn’t as odd as we might think – in fact, we might have seen this disease (CCD) before. Perhaps even in the 1800s. In short, it seems that the answer to this problem is not as simple as banning some pesticides (though restricting their use may be a piece of the solution). I wish it were.

Saving your ash

My earlier post regarding plans to replace the monoculture of ash trees at the Gateway Arch Monument in St. Louis, MO with a monoculture of Lindens prompted a question about options for treating ash trees for emerald ash borer. This is a complex topic so I wanted make sure I had time and space to respond completely.

First, the best and most current source of information regarding treatments for EAB is the Multi-state bulletin “Insecticide Options for Protecting Ash Trees from Emerald Ash Borer” which is available as a full-color .pdf on the EmeraldAshBorer.info website. Anyone who lives in or near EAB-affected areas and is considering treating their ash trees should take the time to download and read this bulletin.

Here are some key points to consider if you want to save you ash:

It is possible to protect ash trees from EAB with insecticides. There are several examples in and around the original core infestation area in Detroit where arborists have successfully protected trees since EAB first was identified in 2002. There are two general options; protective cover sprays and systemic applications. For most trees, protective cover applications will require professional application with specialized high-pressure spray equipment. Most systemic application will also need to be applied by professional applicators, except for small trees that can be treated with soil drenches of systemic insecticide. To date, the most effective systemic product is emamectin benzoate, sold under the trade name TREE-äge. In various tests, emamectin has shown the highest level of control among products tested and is also the only product that consistently provides more than one year of control. Imidacloprid is also effective as a systemic but will need to be re-applied annually for the best level of control.

The likelihood of successfully treating an ash tree declines rapidly once trees begin to show noticeable crown-die-back. In certain cases, researchers have been able to save EAB-infested trees showing some crown die-back, but once 50% of the crown is affected the tree is likely a goner.

Once started, treatments will need to continue in perpetuity. To me, this is the biggest factor homeowners need to consider if they’re thinking about treating their ash trees. To the best of our knowledge, EAB is here to stay. EAB populations may begin to decline once most of the ash trees in a region have been wiped out, but trees in woodlots and forests that have been killed will continue to sprout, providing host material to maintain an endemic population of beetles for the foreseeable future. Systemic applications can provide control but the products will need to be re-applied every year (imidacloprid) or every other year (emamectin) to be effective.

Effectively treating trees larger than 4” in diameter will require applications by a certified pesticide applicator and may cost several hundred dollars per tree. Homeowners need to carefully consider the cost of on-going treatments versus removal and replacement.

Mention of trade names does not imply in endorsement. Read and follow label directions when applying pesticides.

Pesticides and Wildlife

If you follow this blog then you know that I write a lot about pesticides. They’re something that I enjoy reading about and studying. For whatever reason, I find them fascinating. That said, they can be some of the worst things for wildlife. But there are pesticides that are more “wildlife compatible” than others, so today I’m going to cover some of the worst pesticides that you can use in terms of wildlife, and some of the pesticides that might be more acceptable (though far from perfect).

First, here’s a brief rundown of pesticides that have been some of the worst wildlife offenders over the years. Fortunately most of these are gone.

1. DDT – long gone (though I know people who still have old bottles locked up in chemical cabinets here and there). Modern evidence points to it not being as bad for human health (cancer) as many made it out to be, but it was a mess in terms of environmental effects — it built up in the environment (it is stored in the body and is not rapidly excreted — in large part because it isn’t water soluble — so when a predatory bird ate a small mammal who had DDT on (or in) it, all of that DDT would stay in the bird — and the DDT from the next mammal it ate, and so on — this is called biomagnification) and resulted in predatory birds producing thin-shelled, barely viable eggs. Another problem with DDT was that it lingered for a long time — it doesn’t break down quickly. It had other problems too – but the biomagnification and persistence issues were the most obvious and, at least to me, the scariest.

2. Endrin – Relatively closely related to DDT, but a lot more toxic to a lot more animals and so a lot scarier. Once upon a time this stuff was used to all but sterilize fields. Toxic to everything that moves, and, like DDT, it built up in the environment. This stuff was (fortunately) never really used by homeowners.

3. Temik (aldicarb) – Nasty, nasty, nasty. EXTREMELY high acute toxicity, AND it’s water soluble. A pesticide which I have had to use in the past. Apply it to a tree (I was working with pecans when I used it) and that tree’s foliage would be free of any insects. And, amazingly, the stuff didn’t translocate to fruits and veggies – if it weren’t so darn toxic to things besides insects it would have been a great insecticide – some people still consider it a great insecticide. This stuff was known for its misuse. Apply it near a weed which deer eat and that weed would absorb the pesticide and poof! No more deer. Agonizing death too. Wolves and coyotes could be poisoned with just a little bit of tainted deer meat. This stuff wasn’t supposed to be used by homeowners, but, again, it is known as much for its misuse as its use.

Fortunately most of those over-the-top killers are gone or on their way out. Still, in your garden you do have the opportunity to use some poisons which it would be best for you to avoid if you’re interested in saving/protecting wildlife. These poisons are called “broad-spectrum” poisons and they are preferred by many because they kill so many different types of pests. Unfortunately being able to kill many kinds of pests usually also means that they’re able to kill many types of good creatures. Many pesticticides such as sevin (carbaryl), pyrethrin, orthene (acephate), and sulfur are broad spectrum poisons that you should avoid, but here are some that, if you want to conserve wildlife, you should be especially wary of.

1. Permethrin – This is probably the most used broad spectrum insecticide used around gardens today. It will kill just about any insect which it touches and it lasts for about 10 days. It is certainly effective, but it shouldn’t be used by anyone who wants to encourage insects or the birds who eat insects in their gardens.

2. Metaldehyde – This is a very effective slug poison. It is both attractive and deadly to dogs and cats, and is thought to affect birds and small mammals as well though there aren’t as many documented cases of wildlife poisoning as there are of domesticated pets being poisoned.

3. Copper sulfate (Bordeaux mix) – This is an organic fungicide that is often overapplied because it is considered safe. It can limit the plants which grow in an area, and it is extremely toxic to aquatics – keep it away from water. Finally – copper doesn’t break down – as you use it over the years it will build up in your soil – so try to stay away from it.

And finally, here are some which, if they are used properly, are less likely to affect wildlife.

1. Kaolin clay – it’s not popular, but it’s out there if you look for it. This is a type of clay which it sprayed onto plants to protect them from insects. It tends to work pretty well (it’s not perfect), but it has minimal effect on wildlife.

2. Insecticidal soap – It will kill some insects that you don’t want to kill, but it’s a heck of a lot better than permethrin. It is unlikely to hurt mammals or birds.

3. Roundup – The controversial part of me wrote this. Roundup has been implicated as doing all kinds of things to aquatic organisms, but, if it is only sprayed on the leaves of the plant you want to kill, it is not going to cause any significant environmental damage (besides removing a plant that wildlife may want for food).