Legislating Behavior and #Beewashing

Bees have been on my mind an awful lot, lately. And that's saying something ~ considering that I'm an entomologist who has spent a lot of time studying the bees the live in our gardens and parks, as a way to better understand how to garden in ways that protect (rather than harm) these beautiful jewels of the garden.

One of my favorite bees:  Agopostemum sp. (probably, Agopostemum virescens) on a sunflower in Spokane, WA.  Photgrapher:  Gail Langellotto

So, on a normal day, I think about bees quite a bit.  But lately, everywhere I turn, bees ~ and issues related to their conservation and protection ~ have been hitting me upside the head.

First, there was the news that Jeff Reardon (D-Portland) is considering legislation to restrict home gardener use of four neonicotinoid insecticides:  dinotefuran, imidacloprid, clothianidin and thiamethoxam.  Master Gardeners keep asking me what I think about this development, and our discussions have been really interesting.

Second, I received an email announcing that the Bayer Bee Care Tour is coming to Oregon.

It can be tough to write about pesticides and bees in such a public space.  There's so much rhetoric surrounding colony collapse disorder, bees and neonicotinoids that it can be difficult to separate sound science from sound bytes.

This is made even more difficult by the reality that sound bytes are easy to digest and even easier to propagate via the internet.

• Sound byte:  neonicotinoids are killing honey bees.

By contrast, what we learn from sound science is usually much more complex and nuanced to communicate.

• Science byte:  Many insecticides can have harmful impact on honey bees.  These harmful impacts are most apparent when pesticides are mis-used, such as being applied to plants in bloom or to areas with a lot of bee activity.  In addition to insecticides, habitat loss and development, the variable nutritional quality of a bee's diet, parasites and pathogens are implicated as being major threats to honey bee health.  It seems that honey bees are so immune-compromised, that adding on one additional stressor can have dire effects on hives.  But, if we focus on the impact of pesticides on honey bees, it's important to point out that beekeeper applied pesticides (to keep Varroa mites an other honey bee pests at bay) are a major source of honey bee exposure to pesticides.  It's not just growers applying pesticides to crops (although, this is also an important part of the picture that stresses bees).  But even if we take pesticides applied to crops out of the picture, honey bees would still be exposed to pesticides.  Bee keepers are really challenged to keep healthy hives with so much pest pressure on honey bees (mites, diseases, fungi), and so few options for control.  And, I could go on and on and on . . . because the story really is so complex.

But, I want to write about these things, because a major goal of my program is to ensure that home gardeners are informed and educated about current topics ~ so that they can make the best decisions for their particular gardening situation.  Knowledge is power, right?

So what do I think about the potential ban on home gardener use of neonicotinoids?  Well, it's complex (of course!).  I see value in neonic insecticides, and I have concerns about neonic pesticides.

Here is where I see value in neonics:

1.  I like that they can be applied as a soil drench, which is a much easier pesticide application method for homeowners who need to treat a large tree or shrub, compared to a foliar insecticide spray.  I have seen too many bad examples of hose-end sprayer applications of insecticides to trees (e.g. homeowners standing underneath the drip line of the tree they were treating, or not being aware when the pesticide runs out ~ so that they continue to spray the tree with their hose ~ basically washing off the pesticide that they just applied).  Soil drenches, by comparison, are easier for most homeowners to apply in a way that does not expose them to the toxin, and in a way that may better target the intended pest ~ rather than dousing all insects that are in the canopy.
2. Neonics have been a useful tool in protecting at risk trees (ash trees in the Mid-west) and ecosystems (hemlock forests in the NE) from large scale loss because of emerald ash borer or hemlock wooly adelgids, respectively.  In these instances, the products have been a useful tool in an overall integrated pest management approach to protect trees.  The IPM approach relies heavily on monitoring and quarantine in these instances.  The pesticides are not the first tool pulled out of the toolbox ~ but they are one aspect of an overall approach to protecting these trees.  And, these trees are pollinated by wind, and not insects ~ which reduces risk to bees and other pollinators.

Here is where I have concerns about neonics:

1. My biggest concern over the last few years has been that most homeowners don't understand how persistent a neonic can be in a tree or a shrub.  I've written about this in a past blog post, and I've lectured on this extensively over the past few years ~ trying to raise awareness of this issue.  But, if you're reaching for a neonic in response to a one-time, ephermeral issue with aphids in your trees ~ you're reaching for the wrong product.  Better yet, many aphid outbreaks, if allowed to run their course, tend to disappear on their own.
2. Honestly, many plants are fairly robust to pest damage.  The plants often recover.  A plant's tolerance for damage is often less than a gardener's tolerance for damage.  But, neonics are so easy to apply as a soil drench, that I worry that folks reach for them too often ~ as a quick and long-term way to keep their trees, shrubs and other woody plants free from damage.  This isn't IPM.  IPM is a well-thought out and informed approach to pest management that makes optimal use of all IPM tools, so that pesticide applications are reduced, targeted and effective.  
3. I of course am concerned with the data that is accumulating on sub-lethal impacts of neonics on bees who gather nectar and/or pollen from flowering trees or shrubs that have been treated with a neonic.  The low doses of pesticide the bees get from the blooms is not enough to kill them, but it can be enough to change bee behavior in a way that has negative impacts on the hive.

What do I think about the proposed ban on neonics?  I have mixed emotions.

1.  If banned, I guess I wouldn't have to worry about emphasizing the potential for long-term persistence of neonics in woody plants.  It wouldn't be a matter of educating homeowners to make better decisions about the products ~ because homeowners wouldn't have a choice.
2. But ~ if banned, I'm really concerned that homeowners will instead reach for pesticide products that are broad-spectrum, foliar insecticide sprays.  These sprays have a much greater potential for harm to human health.  And, if mis-applied (such as the hose end sprayer example I gave earlier), these sprays could run off of the tree canopy and do real environmental harm ~ not to mention their broad impacts on insects that would be contacted by the spray.
3. And, because of the value demonstrated by neonics in protecting at-risk, wind-pollinated trees, I do see a role for neonics in an IPM approach to plant protection.

What about my thoughts on the Bayer Bee Tour?

Well, the original stops on the Bayer Bee Tour included 'corn belt states'.  The tour appears to have been held from Feb. 26th-April 3rd, 2013.  But now, the Bayer Bee Tour is making its way to Oregon.  How curious, that the timing of a new stop on the Bayer Bee Tour happens so soon after Jeff Reardon's proposed legislation.

I'm not against Bayer ~ or any agrochemical company.  Bayer helps to develop new pesticide products that can be important tools in an IPM approach to plant protection.  And ~ before you jump on me for that last sentence, consider that one of the reasons that bee keepers are so challenged by Varroa mite is that there hasn't been an investment in developing new products for managing mites in bee hives.  Growers need tools to manage plant pests in the context of a well-planned IPM program ~ and without access to high quality tools, there is the potential for increased use and reliance of inferior tools.

I'm instead annoyed that the Bayer Bee Care Tour has rented facilities at major universities (Ohio State, Univ. of Illinois, Iowa State, University of Nebraska, University of Minnesota . . . and now, Oregon State University), and marketed it in a way that suggests that OSU is a collaborator on the tour.  Although completely within their right (these facilities are available for any group to rent and use), I worry that their Bee Tour announcement promotes the false impression that these stops have been planned with and endorsed by the Universities.  When in actuality, the entomologists I've talked to at Oregon State were largely caught by surprise by this upcoming Bayer Bee Tour stop, and were only called after the fact by Bayer to see if they would participate in a panel discussion (most, if not all, have said 'no').

It seems that the more open and inclusive approach, if the goal is to align Bayer's bee protection efforts with what is going on at Land Grant Universities, would be to invite Oregon State researchers to the table from the beginning ~ rather than trying to tack folks on as an afterthought.

Six Ways to Reduce Your Pesticide Use

It's the New Year ~ that time of year when many people resolve to do something better in the coming year, than perhaps they did in the past year.  Most resolutions have to do with getting healthier in some way, shape or form ~ whether it our physical health or our financial health.

In case your resolution has to do with your garden's health, I thought I would offer up XX ways that you can work towards reducing your pesticide use.  Some of these approaches require nothing more than a shift in perspective.  Others will take more time and effort.  But all are capable of having the effect of reducing pesticide use ~ which is generally good for the health of our environment, pets and families. 

1. Stop acting like organic pesticides aren't pesticides.  Many people believe that anything labeled with the term 'organic' equals 'no pesticides'.  They mistakenly believe that organic produce hasn't been sprayed with pesticides.  They mistakenly believe that they can use a pesticide labelled as 'organic' with total impunity.  And unfortunately, some folks tend to use more pesticide, simply because the pesticide is labelled as 'organic'.  As a general rule, pesticides ~ including organic pesticides ~ are formulated to kill or deter something.  Stop spraying it everywhere, thinking it's safe.  All pesticides should be used judiciously and thoughtfully ~ taking care to limit use only to when and where needed.

Organic pesticides are still pesticides ~ formulated to kill something.  Use judiciously.

2.  Make peace with spiders.  I adore spiders.  I think they're absolutely adorable!  If you have a chance to look at them under a microscope, you'll see that they're cute and fuzzy ~ not unlike a teddy bear.  And, they're great allies in natural pest control.  But I get that some people are seriously arachnophobic.  If you simply can't tolerate spiders, please don't reach for a pesticide.  The thought simply breaks my heart.  Instead, try to get the spiders to relocate.  If they're on your porch, try installing an ornamental porch bracket that will take away anchor points from web-building spiders.  Or, consider installing a yellow-hued porch light.  Yellow lights attract fewer night-flying insects, which will attract fewer hungry spiders.

Lynx spider in an azalea blossom.

Porch brackets can take away web-building sites for spiders.  Source of image:  http://victorianrevival.wordpress.com/

3.  Build diversity into your garden.  Diverse gardens, with an array of plant families, shapes, colors, sizes, and bloom times also tend to have a diversity of insect herbivores (sometimes called pests).  But, the trick is that even though diverse gardens tend to have a greater diversity of pests, these pests tend to be at lower abundance!  Why?  It may be that a diversity of natural enemies keep them in check.  It may be that a diversity of plants keeps them from exploding in abundance on a single plant type.  Or, it's more than likely a combination of these factors.

Marion Garden in Salem, OR.

Marion Garden in Salem, OR.

4.  Rethink your approach to early-season lawn weeds.  Are dandelions really all that bad?  Not if you love bees.  Our research has found that gardeners who tolerate early-season lawn weeds are likely to have a greater diversity of bees than those who keep totally pristine lawns.  Why?  In early spring, very few flowers are in bloom that offer spring pollinators access to nectar and pollen.  Dandelions are one such flower that helps early season pollinators get a jump on their season.  If you want to keep your lawn dandelions in check, try to dig this perennial weed out, so that you get the entire taproot.  Target young dandelions before they set seed and before they have a chance to grow a large taproot that will nourish them for many years.  Make sure your lawn is healthy and full, to crowd out dandelions.  Or, plant a dense flower bed, with no bare spots where dandelions can flourish.  Or, adjust your tolerance, and recognize that a dandelion isn't the worst thing that could grace your garden.  Invasive plants, such as cornflower (Centaurea cyanus), English Ivy (Hedera helix) or butterfly bush (Buddleia davidii) are much more damaging to the environment and to local economies than are a few dandelions.  It would be much better to target your weed-hating energy towards these plants, than towards dandelions.

5.  Take regular walks in your garden.  This will help you notice when things 'don't look quite right'.  Regular walks in your garden are not only good for the soul, but their good for an IPM approach to managing pests in your garden.  When you notice that something doesn't look quite right, stop and take a closer look.  Often, you'll catch a pest problem in its early stages ~ when it will be easier for you to manage the problem.  Problems caught early usually require fewer (or no) pesticide, compared to those that are allowed to grow out of control.  A corollary to this suggestion is to keep a garden journal.  This will help you track (and remember) the seasonality of pest problems in your garden, so that you'll be better poised to respond quickly.

6.  Talk to the professionals who maintain your lawn and garden.  Ask them if they use an IPM approach to pest management.  Ask them if their staff are up to date on certifications and continuing education requirements.  Ask them what the major pest issues are in your lawn and garden.  Discuss non-chemical options for managing these pests.  If they don't know about IPM, and aren't aware of non-chemical options for dealing with common garden pests, you might want to look for a better-educated lawn care company.

An Open Letter to Scotts Miracle Gro

Dear Scotts,

I was completely dismayed to read the recent announcement by the EPA that you were sentenced to pay $4.5 million in criminal penalties for illegally applying insecticides to wild bird food products, falsifying pesticide registration documents, distributing pesticides with misleading and unapproved labels, and distributing unregistered pesticides.

In a separate civil suit, you agreed to pay $6.0 million in civil penalties and spend an additional $2.0 million on environmental projects to resolve additional violations that include distributing or selling unregistered, canceled, or misbranded pesticides ~ including products with inadequate warnings or cautions.

You see, Scotts ~ my job is to coordinate the Oregon State University Extension Master Gardener Program.  I know you are familiar with Master Gardener Programs around the United States.  Over the years, you have supported many Master Gardener programs ~ including my own ~ with donations of funds or products.  I believe it was in 2009, Scotts, that you gave the Oregon Master Gardener Association (a non-profit organization that is separate from, but works to support the OSU Extension Master Gardener Program) $1,000 for the purchase of coffee and snacks at our annual conference.  Even though the donation was to the Oregon Master Gardener Association, I personally took a lot of heat from Master Gardeners who felt that accepting a donation from Scott's went against our commitment to sustainable gardening practices.

In answer to those many people who asked me 'why is Scotts sponsoring our coffee hours?', I reminded these concerned Master Gardeners that it is our responsibility to remain objective.  In response to the many, many times I've had Master Gardeners and others ask why we don't exclusively teach organic gardening practices, or why we don't confine our advice and recommendations to only include organic options, I've reminded them that whatever our personal opinions and biases might be, it is our job to remain objective.  Our responsibility is to educate clients about all of the options that are available to them ~ and then let clients choose the option that will work best for their gardening situation.  When working as Master Gardeners, we don't selectively choose among all possible options, to include only those options that we personally favor.

Our job is to educate, and not legislate.  We're descriptive, and not prescriptive. 

I've used these lines, many times, Scotts ~ when Master Gardeners have asked me if they could ignore that your products exist, or even make recommendations against your products.  Our job is to teach ~ and not to make decisions for others.

Oh, but Scotts, I'm now at a cross roads.  You see, in addition to the taglines 'educate, not legislate', and 'descriptive, not prescriptive', another mantra that we repeatedly teach in the Master Gardener Program is 'the label is the law'.  We repeatedly emphasize that the label on a pesticide container is a legal document, that describes legal uses for a pesticide.  In Oregon, Master Gardeners must spend at least 3 and as many as 10+ hours a year taking classes where we bring in our magnifying glasses and carefully read the label on a pesticide.  We talk about potential hazards of the product.  We talk about precautions we can take to reduce hazards to people, pets and the environment.  We talk about how it is illegal to exceed application rates, or to use a product in a way in which it is not intended.  We talk about active ingredients ~ those ingredients that are intended to specifically kill, deter or repel a pest ~ and how those active ingredients must be listed on the label.

And now, after reading about your recent violations of the Federal Insecticide, Fungicide, and Rodenticide (FIFRA) Act, and then doing some more reading to discover that these violations are not your first and that the violations extend to more than 100 of your products ~ my trust in your company and your products has been damaged.

When small, untested companies market products that are little more than 'snake oil' solutions, Master Gardeners are told that they can't include those products in the list of options that they give to clients.  Remember, 'research-based and reliable recommendations' is yet another Master Gardener tagline.

If your company has a history of:

• falsifying pesticide registration documents
• distributing pesticides with misleading and unapproved labels
• distributing unregistered pesticides.
• distributing or selling unregistered, canceled, or misbranded pesticides ~ including products with inadequate warnings or cautions.  

how can recommendations that may include one or more of your products be considered reliable?

I really want to know, Scotts.  How can we trust you after this egregious breech of the public's trust?  What should I tell the Master Gardeners that I teach?  What should I tell the clients who come to us for objective, reliable advice?

Until we can be sure that your products are reliable and legal, how can we in good conscience recommend them to our clients?

Sincerely,
Gail Langellotto
home gardener, and someone who works with many, many Master Gardeners and home gardeners

Pesticide Residues on Fruit and Vegetables

Yesterday, while working on the Growing Healthy Kids curriculum, I was asked to comment on one of the recipes we're planning to include in the revision.  This recipe is intended to support the 'Water for People and Plants' lesson and to encourage kids and their families to choose water over sugar-laden beverages.  The recipe is simply water flavored with things such as lavender, mint, cucumber, or citrus.

My concern with the recipe was that fruit and vegetables may contain pesticide residues, and that we needed to place STRONG cautions on the recipe card.

Here's my line of thinking:

1. The limits for pesticide residues on fruit and vegetables are set by the EPA.  However, although pesticide residues are limited, it is unlikely that fruit and vegetables purchased at the store have zero pesticide residues. 
2. Some of these pesticides are organophosphates.  Organophosphates inhibit cholinesterase, which is an enzyme that insects have - but that humans and other mammals also possess.  Thus, the same pesticides which act against insects also impact humans.  It's no surprise then, that organophosphates are often implicated in cases of pesticide poisoning.
3. Their higher metabolic activity and lower body mass make infants and children more prone to pesticide poisoning, compared to adults.
4. Water is the universal solvent, and is often used to dissolve the active ingredient of many pesticides.

However, this line of reasoning was more of a 'thought experiment'.  Ever curious, I wanted to make sure that my recommendations weren't too severe.  Thus, I decided to work through this issue, using citrus as a model.  I chose citrus, because it tends to have a bumpy rind, which can better 'hold' onto dirt, debris and pesticide residues.  Yes - you could simply peel the citrus rind off of the fruit prior to making citrus water.  However, in restaurants and in homes, it seems to be 'en vogue' to keep the peel.

I searched the USDA Maximum Residue Database for the maximum allowable residue limits (MRL) for malathion (a common organophosphate) on lemon, lime and sweet orange in the United States.  All had a MRL of 8 parts per million (ppm).  It was interesting to note that the MRL of 8 ppm in the USA is orders of magnitude higher than the default MRL for citrus set by the European Union (0.01 ppm), Canada (0.1 ppm), Japan (0.01 ppm), Malaysia (0.01 ppm), New Zealand (0.1 ppm) or South Africa (0.01 ppm).

Although the MRL for malathion on citrus is 8 ppm, in practice, citrus water likely contains far less than 8 ppm.  First, the 8 ppm is a maximum residue level, and not the actual residue level.  Second, not all of the residues are likely to dissolve back into the water.  But, in my line of thinking, it is probably that **some** of the residue will dissolve. And, although I couldn't find many examples of published research on what would be termed 'sub-chronic exposure' (i.e., very low levels of exposure, over an extended period of time), one study performed on mice found no discernible impact of low level exposure to malathion.

So, in one sense, I'm probably being over-reactive.  But, I still maintain that it's better to be safe than sorry - particularly when working with children.  And, with a few easy tweaks, we can easily reduce potential sub-chronic exposures to pesticides.  Thus, there's no real need to bother with a recipe that could potentially expose kids to low levels of pesticide.

What tweaks would I recommend, if you're preparing your own flavored waters at home?

1. Peel cucumbers or citrus prior to placing them in the water.  This will greatly reduce pesticide residues, as the vast majority of residue resides on the outer peel.  Maybe people leave the rinds and peels on because it provides a beautiful shot of color.  However, it's not worth it (in my opinion) to needlessly introduce potential pesticide residue into your water.
2. Follow the National Pesticide Information Center's tips for reducing pesticide residues on fruit and vegetables.  Briefly,  wash produce under running water.  Don't dunk or soak.  Don't use soap, bleach or veggie washing products, as these have been shown to be no more effective than running water, and may even 'trap' residues in pores of the produce.
3. Choose organic over conventionally produced fruit and vegetables.  Organic pesticides aren't necessarily less toxic than synthetic pesticides.  After all, organic pesticides are still pesticides - and pesticides are generally formulated to *kill* something.  However, the major advantage of organic over synthetic pesticides is that organics tend to degrade quicker.  In fact, studies show that organically grown produce has about 1/3 the pesticide residue of conventionally grown produce.
4. For flower-flavored waters or for pastries or other drinks those that use flowers as a garnish, use ones that you've grown in your own garden, so that you can know how they have been grown.  The MRL database doesn't list residue limits for flowers - probably because flowers aren't considered edible crops.  So, when you garnish your cake with pansies, or add lavender as a garnish on ice cream - the pesticide residues may be higher than what you would find in edible crops.  Once again, better safe than sorry - and the best way to be safe is to know 100%, without a doubt how those flowers were grown.

By the way, I love learning new things.  This week, a paper I submitted with my amazing graduate student, Abha Gupta, was accepted for publication in HortTechnology.  Briefly, we re-analyzed published data from the literature, and found that nutrition education programs that have gardening component increased vegetable consumption in kids.  However, nutrition education programs without a gardening component had no such effect.  As part of the revision process prior to publication, I need to make sure that our format is correct, as well as fix minor errors in grammar.  I never knew that the plural of fruit is fruit.  I always thought that fruit was singular and fruits was plural.  Who knew??

Neonicitonoids offer LLLOOONNNGGG Term Protection Against Pests

One group of pesticides that I have been devoting more and more time to in my Master Gardener training classes is the neonicotinoids. This group of pesticides received quite a bit of news this past week, as news outlets reported on two studies that link bees' declines with neonicotinoids.

Imidacloprid is perhaps the most common neonicotinoid pesticide available to home gardeners, as it was the first neonicotinoid to gain widespread use (Mullins 1993). Imidacloprid is a systemic insecticide. When applied as a soil drench or soil injection, it is absorbed by the plant's root system, and distributed to different plant tissues via the plant's vascular system. Imidacloprid can also be applied to plant leaves. This is known as a foliar application. In general, soil applications of imidacloprid take longer to work against insects, compared to foliar applications. However, soil applications of imidacloprid are effective for longer, compared to foliar applications.

There are two primary advantages of using a systemic insecticide, such as imidacloprid, against insect pests.

• First, imidacloprid is highly specific to insects. Imidacloprid is thus less likely to have negative effects on humans and other mammals, compared to other pesticides - such as the organophosphates or carbamates.

• Second, since soil applied imidacloprid is taken up by the plant's roots and incorporated into plant tissues - by definition - only a pest of that plant will get a dose of the insecticide. An insect has to feed on the plant to get a dose of the pesticide. Sitting on the plant is not enough to get a dose. This is one advantage of soil applied systemics, compared to insecticide sprays. With broad spectrum insecticide sprays, every insect in the path of the spray - whether they are the target pest, or a beneficial lacewing - gets a dose of the insecticide. Systemic pesticides diminish these 'non-target effects'. Of course, there is the issue of systemic insecticides being translocated to the nectar and pollen of plants. I'll cover this issue in a future post. Nonetheless, I'll mention here that one way landscape managers try to reduce the impacts of systemic insecticides on bees is by limiting their application to wind-pollinated trees - such as hemlocks.

Other potential advantages of soil-applied imidacloprid include:

• They are easier to apply to trees and large shrubs, relative to foliar sprays, and

• They offer long term protection against pests. In fact, you can often spot those pesticides that are likely to contain imidacloprid as an active ingredient, by looking for phrases such as '12 month control' or 'season long control' on the container.

However, there is much to learn about the long-term persistence of soil applied imidacloprid in trees and shrubs. In fact, the data that is available suggests that long-term persistence may really be LLLLOOONNNNGGGG term persistence.

• Szczepaniec and Raupp (2007) found that toxicity persisted, and pests were absent, up to three years following the application of imidacloprid to potted cotoneaster. It is important to note that the researchers did not sample foliage or look for pests in year four. They stopped their assays three years following the application of imidacloprid.

• Cowles and Lagalante (2009) found that a single soil injection to hemlock can provide between 5-7 years of pest protection, and that imidacloprid was detectable up to 8 years after application. After 5 years, the metabolite imidacloprid olefin was more abundant in tree tissue than imidacloprid. Although the authors of this report note that the olefin metabolite is much less toxic than imidacloprid, Nauen et al. (1999) report that the metabolites (including olefine) of imidacloprid retain toxicity to at least some insect pests.

• Dilling et al. (2010) found that trunk injection of imidacloprid in hemlock trees provided protection against hemlock wooly adelgid for 3-5 years.

• Webb et al. (2003) also found that a soil drench of imidacloprid protected hemlock trees from hemlock wooly adelgid for almost three years - the extent of the assays in this study.

Now, I'm not writing this post to be anti-pesticide or anti-imidacloprid. In fact, imidacloprid has great potential as a tool that ecologists and land managers can use to save ancient hemlock forests from the invasive insect, hemlock wooly adelgid. This insect is having large-scale, ecosystem level effects that threaten unprecedented hemlock loss (Orwig et al. 2002). If we love hemlocks and hemlock forests, then it makes sense to consider imidacloprid as one tool that can be used against hemlock wooly adelgid, as part of a comprehensive integrated pest management plan. Remember that hemlocks are wind pollinated, thus lessening the potential negative impacts of imidacloprid-treated trees to bees.

Instead, I'm writing this post because I worry that too many home gardeners see the advertisement of '12 month control' on the front of the label, and think 'hmmm . . . . why purchase a product that can give me short term control, when I can get one with really long term control? That seems like the best buy!'

If you are having a short-term, one-time problem with aphids on your rose bushes, I'm not sure that imidacloprid is your best choice. In fact, for short-term, one time pest problems on any plant, I'm not so sure that imidacloprid is the best choice. Thus, I wanted to write a post that points out that the long term protection advertised may be RRREEEEAAAALLLLLlllllyyyyyy long term protection.

It's interesting to note that only one of the studies that I listed (Szczepaniec and Raupp (2007)) looked at the long-term persistence of imidicloprid in an ornamental plant. It's also interesting to note that many of these studies could detect imidacloprid (via bio-assay of pests or chemical assays for the active ingredient) up through their last sampling date. Thus, there is clearly more to learn about the persistence of imidacloprid in home gardens.

Are soil-applied systemic insecticides the best choice for pest problems in the home garden?

Are annual applications necessary?

I can't answer these questions - but I think they're important questions to ask.

Kale IPM

Excuse me, but there’s a worm in your pesto.

Kale leaf foliage,
stripped from the leaf 'rib'.

The finished product: kale pesto!

The finished, finished product:
kale pesto on homemade pizza.

Yesterday afternoon, my husband and I harvested kale and basil to make pesto. The basil did quite well this season – with nary a pest blemishing its leaves. The kale, on the other hand, came with several added bonuses that I didn’t want in the pesto:

• Cabbage worm larvae (caterpillars) and eggs
• Aphids - with signs that an infestation was imminent
• Spiders and their webs

We harvested the kale, and I carefully inspected and washed each leaf before cutting the flesh of the leaf blades from the rib. We made a tasty kale pesto, that was delicious on pizza with homemade crust and sauce (shout out to my husband, who is the cooking brains in this operation).

But as I was making the pesto (or, cleaning the leaves, so my husband could make pesto), I knew it was time to go out into the garden to manage the cabbage worms and the aphids, before they got out of control.

Cabbage worms are the larvae (young) of the ubiquitous cabbage butterflies (Pieris rapae) that you see flying around everywhere. The adult butterflies lay their eggs on cruciferous plants: broccoli, cabbage, collard greens, Brussels sprouts and kale. The larvae can’t feed on non-crucifers. Thus, females who make a ‘mistake’ and lay their eggs on a non-cruciferous plant basically doom their young to death by starvation.

I've dealt with the cabbage worms all summer long. Every day when I watered, I carefully picked their eggs off of the kale leaves. I searched the leaves and picked off the caterpillars that hatched from eggs that I missed. I was happy when my husband cleared out a nearby tangle of grape and blackberry canes (i.e. stems), and the spiders promptly migrated from that area and into my vegetable garden. The spiders surely helped to keep the cabbage worm population down - pouncing on caterpillars as they munched on my kale, or entangling the caterpillars in their web. They might even munch on an aphid or two (although, spiders really prefer and need the protein rich meal that the caterpillars offer - much more nutritious than the sac of sugar that is an aphid).

Two cabbage worm eggs
on kale. I picked these off of
kale leaves, as I watered the
garden.

A late-instar cabbage worm,
almost ready to build a cocoon.
I pick these off of leaves, as well.

Spiders munch on cabbage worms
and other insect pests. I leave
these be in my garden.  They're my
pest control buddies.

But, the spiders couldn't do it all themselves. After harvesting and cleaning this batch of kale, I knew that I needed to go out into the garden and use chemical controls. My conundrum, however, is that I wanted to control the cabbage worms and the aphids, but not harm the spiders. I needed to use pesticides that had a 'narrow spectrum' of activity. Narrow spectrum insecticides harm a relatively few types of insects and other arthropods. Broad spectrum pesticides harm a large array of insect types, and are thus more likely to harm both your pest (which you want) and your beneficials (which you don't want).

I went to my pesticide storage container, and decided on 2 products. Both products are organic. When I need to use a pesticide, I prefer using organic pesticides, over synthetic pesticides in my vegetable garden. The major benefit of using an organic pesticide over a synthetic pesticide is that organic pesticides degrade quicker than synthetics, after they are applied. I hate the idea of eating pesticide residues with my vegetables, so when I am treating edible plants, I almost always use an organic product. I want that extra assurance that the vegetables will be pesticide free when I harvest, cook and consume them.

The products are also formulated, so that they will help manage the cabbage worms and the aphids, but that they are unlikely to harm other insects and arthropods. I wanted to protect my garden spiders, afterall. They're my caterpillar eating buddies.

Label of a narrow-spectrum insecticide with the active
ingredient Bt-k (Bacillus thuringiensis kurstaki).

To control the cabbage worms, I chose a dust formulation of a product whose active ingredient is Bacillus thuringiensis kurstaki (also called Bt-k). The insecticide only works against the larvae of butterflies and moths (like, the cabbage worm caterpillar I am trying to manage on my kale). In addition, this insecticide must be eaten in order for it to be effective. Thus, if I sprinkle the dust only on my kale leaves, only those caterpillars that are eating my kale will get a dose of the insecticide. The brand name of the product doesn't matter. Look for the active ingredient (Bt-k), formulated as a dust.

Pay attention to the directions for use. You only need 0.5-1 oz per 50 square foot of garden. One ounce = 2 tablespoons. Thus, for a standard sized 3 foot by 5 foot garden bed, you only need one third to two thirds of a tablespoon. Since this product often comes as a dust formulation, and is packaged in way that you can simply 'shake out' the pesticide, much the same way you might sprinkle Parmesan cheese on top of spaghetti, it's unfortunately easy to over apply this pesticide. To avoid over applying, set the dispenser so that the pesticide will lightly sprinkle out of the packaging. Don't open the dispenser all of the way when applying.

Note that you only need 0.5-1.0 ounces
per 50 square feet of garden.  This is a
very small amount!  Be careful not to
over apply.

Instead, apply a fine dusting, with the
container open only the tiniest amount.

If you apply the dust with all of
the holes open, you're likely to over
apply this insecticide in your garden.

To control the aphids, I chose a ready to use spray formulation of insectidal soap, which has an active ingredient name of 'potassium salts of fatty acids' (or something similar). Insecticidal soaps work by degrading the exoskeleton of the insect. Thus, they best against small, soft-bodied insects, such as aphids, whiteflies or thrips, and tend to have little effect on larger, harder-bodied insects such as beetles, caterpillars, grasshoppers. Insectidal soaps must contact the aphids in order for the insecticide to work. Unlike Bt-k, insectidal soaps do not require the insect to eat the toxin. Instead, the insectidal soap must contact the aphids in order for the insecticide to work.

Label of an insecticidal soap product, with the
active ingredient 'Potassium Salts of Fatty Acids'.

I had another option available to me. When my flea beetle (and my aphid) problem became too big for me to manage using physical controls (i.e. picking the beetles off of the plant) or biological controls (i.e. relying on parasitoids to help me control the beetles), I needed to incorporate a chemical control into my integrated pest management approach. I decided to use an organic pyrethrin. Pyrethrins are an organic insecticide that works against a wide range of insects. Even though it is an organic insecticide (and thus has the advantage of degrading rapidly in the environment), I avoid using this product when I can. It surely helped me to control the flea beetles and aphids on my potatoes, but if I had accidentally sprayed the pesticide onto a parasitoid or a bee, it would have probably killed those beneficial insects. Because the aphid problem on my kale could be managed with insecticidal soaps, I chose not to use this broader spectrum and combination product.

Note that the product below has two active ingredients: pyrethrins plus potassium salts of fatty acids (i.e. insectidal soaps). This is an example of a combination product. The product above has only one active ingredient: potassium salts of fatty acids.

Label of a combination insecticide, including broad
spectrum pyrethrins, as well as insecticidal soap.