Category Archives: Pesticides

Triclosan – The Pesticide You Might Be Using Without Even Knowing It!

The term “pesticide” is a broad term that includes any compound that kills “pests.” There are miticides, bactericides, fungicides, insecticides, herbicides, rodenticides and a host of other “-cides” that all fall into the category of pesticide.

Gardeners today are more aware of the use of pesticides than they were decades ago. The increase in organic gardening and the negative publicity of some pesticides (i.e., RoundUp) has led to a greater awareness of the benefits and risks of using any pesticide.

But there’s one pesticide that a lot of people don’t even think of as a pesticide. Walk into any grocery store and if you want to buy dishwashing soap, hand soap or body wash, you’ll find all kinds of products labeled “antibacterial.” And if you look closely, you’ll find that the active ingredient in all of these products is triclosan (or the closely related chemical triclocarban).

Triclosan is a bactericide – a pesticide. It was originally used in hospitals as a surgical scrub but since the late 70’s it’s found its way into a multitude of products.

You can find triclosan in soap, deodorant, lipstick, cosmetics, paints, toothpaste, mouthwash, clothing, kitchen utensils and even pencils! Often it’s hidden under the name Microban where it’s used to limit microbial growth that can cause stains and odors on a lot of kitchen and children’s items – like the Ticonderoga® Pencils with Microban Protection.

I don’t think there’s a person out there who would gargle with RoundUp, shower with 2,4D, coat their skin with Sevin or soak their clothes in Malathion, but unsuspecting consumers are doing just that. Sure, triclosan is a lot less toxic than these other chemicals but it’s still a pesticide – and a pesticide that we don’t even need.

17vz0bud5d9khjpgPlain soap and water cleans as well as any antibacterial soap. And plain soap doesn’t add a pesticide to our bodies that can be absorbed through our skin. Tests have shown that 75% of the population have triclosan in their bodies. It’s been found in breast milk, blood, and urine. While there still don’t seem to be clear studies showing direct harm from triclosan, many believe that it affects hormone balance and can alter the gut bacteria and increase antibacterial resistance in microbes.

Anyone who has followed my blog knows that I’m not opposed to pesticides. But when I use them, it’s always to address a specific problem and I used the least amount possible of the safest product for the shortest period of time.

That’s why triclosan makes no sense to me. There is no specific problem that it addresses except Americans’ deeply ingrained germaphobia! If you use antibacterial products you’re exposing yourself to it for a long time. And many are raising the question of just how safe it is.

I always read the label when I buy an herbicide or insecticide. Now I’m reading labels when I buy soap, toothpaste, and moisturizer. I’m reading to make sure that there isn’t any triclosan in the product. I’m not about to start washing with a pesticide!

(Also see Scientific American’s article, “A Key Antibacterial Soap Ingredient Must Go” by Maricel V. Maffini and Mae Wu.)

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African Violets and Soil Fungus

I seem to have an issue with african violets and various kinds of fungi. In the past I’ve written about pythium and how it decimated my plants.

Now I seem to have some new fungus, or better said, fungi. In the spring I got some leaves of plants from Lyndon Lyon Greenhouses in New York. The leaves came quickly and were in very good shape when they arrived. I took the time to “sterilize” the potting mix that I was using and assumed that all would be well.

A few weeks after potting up the leaves I noticed that there was a brown fungus growing on the top of the soil. When the pots dried out and I watered them, a puff of brown powder would emerge from the top of the soil when the water touched it – that was the fungi spreading its spore into the environment!

I kept the pots of leaves separated from other plants but I noticed that a schefflera that I’d potted with the same potting mix had identical brown fungus growing on the surface of the pot. It’s obvious that there was some kind of fungus spores in the bag of potting mix that I used and my attempt at sterilizing the soil didn’t accomplish its purpose.

Fungi on Potting Mix

Fungi on Potting Mix

I was tempted to throw out the african violet leaves but I decided to wait and see what would happen. As it turns out, this brown fungus didn’t seem to affect the plants. Small plantlets started to grow but at the same time that the plantlets were growing, a white fungus started to grow on the surface of one of the pots. I’m not a mycologist so I don’t know what kinds of fungi these are but I know I don’t want them spreading to the rest of my plants.

After some searching I found a copper fungicide that’s said to safe for african violets. Its active ingredient is copper octanoate, a kind of copper soap. The way copper works as a fungicide is to denature proteins and thus disrupt the growth of fungi. It can have a pytotoxic effect on plants as well if the concentration of copper is too high. The solution I’m using is only 0.08% copper octanoate so I’m not too concerned that it’ll harm the violets. If they do seem affected, I’ll flush the plants and soil with water and hope for the best.

I sprayed the surface of the soil and will repeat this in about a week. I’ll continue to keep an eye on the soil and when it comes time to pot the plantlets, I’ll remove most of the soil from their roots and dip the entire plant in fungicide. This should stop the fungi and keep it from becoming a permanent part of my indoor garden.

I’ve heard of people getting bad bags of potting soil and ending up with a fungus gnat infestation. I’m glad I didn’t get any gnats in that bag of soil; I just got the fungus! Here’s hoping the copper octanoate is the answer to my problem.

Time to Start Bringing the Houseplants Inside

Philodendron

During the summer I put my larger foliage plants outside on the fire escape. It’s a western exposure but there’s a large oak tree that keeps the area shaded. I’ve found that plants like ficus, dracaena, philodendron and others do well in this location.

But when the weather gets cooler, I know it’s time to start bringing the plants back inside the house. But before I bring them inside, I want to make sure that I’m not bringing insects into the house. By this point in the season, the insects are slowing down but if I bring any into a warm house, they’ll come back to life with a vengeance and once they’re in the house, it’s hard to control them.

To make sure this doesn’t happen, I check the plants closely to see if there are any visible insects. If there are, I wipe them off the leaves and/or stems with a paper towel.

But even if I can’t see any insects, there can still be some living in the leaf whirls, hiding in the places where the petioles and stems meet or there may be eggs that I don’t notice. So while the plants are still outside, I spray them with an insecticide to kill any remaining insects.

In the past I would drench the plant with insecticidal soap, an organic product that you can find in any garden center. That worked pretty well but lately I’ve been using a systemic insecticide that contains imidacloprid. It’s available in a spray that’s quickly absorbed by the plants. It also comes in a granular formula that can be applied to the soil a few weeks before bringing the plants inside. The benefit of the granular formula is that it will also kill any insects in the soil and limit fungus gnats when the plants are in the house.

The final step before bringing the plants inside is to give them a shower. After a summer outside the leaves can get a little dirty so I put each plant in the shower and spray the top and bottom of all the leaves.

I have a few weeks before the plants have to come inside. It’s time to check for insects and apply the insecticide. The other thing I have to do is find a place to put all of the plants – that’s the truly hard part of bringing the plants inside!

Bean Leaf Beetles Chew!

I recently noticed that the filet beans that I had planted had germinated well but all of the first leaves had holes in them. On some of the plants, at least 50% of the leaf surface was gone. I couldn’t see any insects at the time so I was pretty sure that it wasn’t caused by a caterpillar. (If a caterpillar has been chewing a plant, you can usually find it somewhere on the plant.)

Have ruled out caterpillars, I remembered the old entomology adage – “bugs suck and beetles chew.”

True bugs  are insects that fed by using their mouthparts to suck the juice from a plant. The true bug everyone in PA is talking about is the brown marmorated stink bug. This pest doesn’t bite or chew; instead it inserts its tube-like mouthparts to suck the sap of a plant. The brown marmorated  stink bug can’t chew the leaves of an apple tree but it can suck the juice from a growing apple which will cause the mature fruit to be disfigured.

On the other hand, beetles are insects that chew plants and usually create holes in the leaf tissue. A beetle that every gardener in PA knows about is the Japanese beetle. These insects can turn a rose leaf into a skeleton in no time because they’re chewing insects.

Well back to the beans – since I saw holes I knew that something was chewing them and that something was probably a beetle. After a little online search, I found the culprit – the bean leaf beetle.

Adult Bean Leaf Beetle

This 1/4 inch long beetle ranges in color from yellow to red and may or may not have spots. It overwinters as adults in leaf litter and other protected areas, emerging in the spring to feed and reproduce. The female beetle lays her eggs at the soil surface near beans and other host plants. The larva feed on the roots of the plant and after about three weeks build a little cell in the soil where they pupate. A week later, adults emerge and start the cycle again.

Bean Leaf Beetle Damage

The damage to the beans is worse than I’ve ever seen. I bet that’s because of the very mild winter we had – a mild winter means that more of the beetles survived. The good news is that this beetle is easily controlled by spraying the plants with an insecticide containing pyrethrins, an organic substance that’s extracted from a particular kind of chrysanthemum. One spray of a pyrethrin based insecticide and the new leaves have no holes and look great.

I’ll have to keep an eye on the plants in the coming weeks, but if I see more holes in the bean leaves, I now know that they’re caused by bean leaf beetles and they’re easily controlled.

Fungus Gnats

If you’ve ever had plants growing in your home and found that there were little flies hovering above the soil, you’ve had an encounter with fungus gnats (Bradysia species). These 1/8th inch long insects are seldom harmful and they don’t bite or carry disease; they’re more of a nuisance than anything else.

Adult Fungus Gnat

The life cycle of fungus gnats is similar to the butterfly in that both undergo a complete metamorphosis. The adult fungus gnat lives 7-10 days and during that time the female gnat will lay more than 200 eggs on the surface of moist potting soil. Within a week the eggs hatch into larvae – the caterpillar stage. The small maggot-like larvae live in the top few inches of the soil. The larvae spend 2 weeks eating their fill of algae, fungus and decaying plant matter. (If the infestation is really bad, they can start eating live plant roots but that’s unlikely to be a problem in the home.) Next, the larvae pupate in the top-part of the soil. This is their cocoon stage. In less than a week another crop of fungus gnats emerges from the pupae to start the cycle over again.

Every spring I have an infestation of fungus gnats. The female gnat is attracted to potting soil with a high peat content – that describes all of my potting soil. But they also need the soil to be moist. If the top inches of the soil dry out, the eggs don’t hatch and any larvae die and the cycle is interrupted.

During the fall and winter I tend to keep my plants on the dry side so gnats aren’t a big problem. In the spring I propagate many of my plants and also start seeds. As a result, I have a lot of pots filled with peat-based medium that can’t dry out or the cuttings will die and the seeds won’t sprout. No wonder I have fungus gnat in the spring!

There are a few ways to control gnats. If you only have a few plants, you can remove some of the soil from the top of the pot and replace it with a layer of sand or pebbles. The female gnat wants to lay her eggs on moist peat, not sand and rocks.

If you have a lot of plants, avoiding overwatering and allowing the pots to dry out before watering will limit the gnat population. There is also a systemic insecticide called imidacloprid that comes in a granular formula. When added to the top of the soil in a pot, it kills the gnat larvae. It is also taken up by the plants roots and will kill insects like aphids, mealybugs and scale. This product can only be used on ornamental plants. If you’re going to eat any of the plant that you’re growing (i.e. an herb plant), you never want use a systemic insecticide.

The other way to control fungus gnats is by using sticky cards. These bright yellow pieces of plastic are covered with a substance that makes them sticky. The cards can be attached to a popsicle stick and put in a pot or hung in the area where plants are grown. The adult gnats are attracted to the color yellow and when they land on the card, they’re stuck. While this won’t eliminate them, it will keep their population in check. I’ve found them to work especially well around trays of seedlings.

It’s spring and it’s fungus gnat time. But this year, with a little judicious use of imidacloprid and lots of sticky cards, I’ve got the gnats under control… not gone but under control.

Controlling Crabgrass

Early spring is the time of year to prevent crabgrass in your lawn. I just spread Scotts Turf Builder with Halts crabgrass preventer on the lawn. A few years ago I tried going the organic route and used a corn gluten product that was supposed to stop crabgrass. It smelled nice, like masa harina, the corn flour used in making corn tortillas! The problem was it didn’t work very well for me.

Crabgrass

So I’m back to Scotts. The product that I put on the lawn has a high nitrogen fertilizer in it that will help the grass green up quickly. It also has a crabgrass preventer that Scotts calls Halts. I did some checking to find out what  Halts is – it’s the chemical dithiopyr.

In the world of herbicides, there are preemergent and postemergent herbicides. Preemergent  herbicides prevent weed seeds from germinating and/or developing normally. Postemergent  herbicides affect weeds that are already growing.

Dithiopyr is a preemergent herbicide – it doesn’t kill crabgrass that is already growing. Instead it prevents the crabgrass seeds from growing into crabgrass plants. It’s put on the lawn in early spring when the forsythia bushes are blossoming. This is the time to apply dithiopyr because crabgrass seeds haven’t started to germinate but they will begin to grow within the next 2-3 weeks as the soil warms.

I’m fascinated by the way this chemical works. Dithiopyr is a mitotic inhibitor of normal cell division in the germinating crabgrass seed. If you remember back to biology class, mitosis is the process by which cells multiply. During seed germination, mitosis is happening at a rapid rate.  Dithiopyr affects mitosis in germinating crabgrass seeds by inhibiting the formation of the microtubules which are necessary for the chromosomes to separate correctly during cell division.  When dithiopyr is present, the germinating crabgrass seeds are unable to grow into healthy plants because its cells can’t divide normally. And that means no crabgrass!

But whether you care about how this herbicide works or not, the important thing is that it works. If you want to have a crabgrass-free lawn, a preemergent herbicide is the way to go.