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Archive for May, 2011

“My green thumb came only as a result of the mistakes I made while learning to see things from the plant’s point of view.”  H. Fred Dale

Of all the great quotes I’ve read about gardening, this one might be the best. There’s a lot of hard-earned truth, and no doubt a few dead plants, behind these words. Above all else it tells us that gardening is about being observant — it’s about learning from our successes and our failures.

As Mary Beth and I have talked about gardening and what to write about in our posts over the past couple of years, we come back to this truth over and over again: our plants and gardens will show us what they need if we just look at what’s going on from their point of view.

Ignore the ads blaring from the TV set telling you to drench your living soil with systemic chemicals that will kill all that’s bugging you in your garden. What it will kill is your soil’s ability to support healthy plants. Do it and you’ll be hooked into an endless cycle of applying chemical cocktail after chemical cocktail to solve the problems you created with that first application. (Never mind what havoc they might wreak on your health and that of your kids, your pets and every other creature that calls your garden home.) These ads horrify us!

Better is to use what nature provides to improve our soil’s tilth and our plants’ health. Natural manure from cows, horses, chickens, etc. is far superior to chemicals. Natural pesticides are better than synthetics if you really need them.

Your plants will tell you if they’re getting what they need. If they are stressed they are more likely to be attacked by insects; or lacking enough sun or nourishment, they’ll fail to thrive. Or maybe a particular plant is just not right for your microclimate so it doesn’t perform up to its potential. On the other hand, you might have had success with a plant that the experts say isn’t appropriate for your area. You be the judge. Take advice, but apply it with caution until you can see that it will work for your garden. (And keep a journal so you don’t have to repeat those lessons next year.)

I was reminded of the importance of being observant this morning when I watched a video of Tom Trantham of Happy Cows Creamery. Tom was on the brink of losing everything when his cows showed him the way to fix his mistakes. His story is nothing short of a miracle, but it took Tom’s willingness to really see and learn from what was happening. Even though his story is about his dairy farm, its basic principles apply to our gardens as well.

So as we embark on another season in our gardens, let’s all take the time to see what’s really happening and to learn from it. Whether you succeed or fail, ultimately you will learn from what you’ve done and your green thumb will prevail.

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Block Island, Rhode Island

Irvine, California


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Of all the organic products we can use to eliminate pests in the garden Spinosad (spin-OH-sid) has perhaps the most curious back story.

A scientist who was part of a team that was searching for new naturally occurring pest controls was on vacation in the Caribbean in 1982. He was poking around an old abandoned rum distillery and decided to take a few soil samples home with him. Back at the lab they fermented the samples and three years later found that the products of the fermentation had insecticidal activity. To make matters even stranger, this new species of soil dwelling bacterium called Saccharopolyspora spinosa, a rare actinomycete, has never been found anywhere else in the world. It is one of those things you read and think, “What are the chances?”

Spinosad is safe for use on ornamentals, vegetables and fruit. It must be consumed by the insect to be effective. It can be used to control a variety of pests including:

  • Cabbage worms
  • Caterpillars
  • Coddling moth
  • Corn borers
  • Fruit flies
  • Leaf beetle larvae
  • Leafminers
  • Rose slugs (sawfly larvae)
  • Sawflies
  • Spider mites
  • Thrips
  • Tomato hornworms

A note of caution here: Spinosad is highly toxic to caterpillars. That means that it will kill good caterpillars as well as bad. If you have a butterfly garden or plants that attract butterflies, DO NOT spray Spinosad when these caterpillars are feeding. You will kill them.

Spinosad is mildly toxic to fish so be careful spraying it around ponds. It can be toxic to bees and other non-leaf feeding insects if they come into contact with it before it has dried on the leaf. That means that you should spray the product only in the recommended amounts (READ PACKAGE DIRECTIONS!), at the recommended intervals, and at dusk when bees and other beneficials are less active. This gives it time to dry on the leaves where it will still be ingested by pests, but where it will not affect the beneficials.

Spinosad has a very low toxicity for mammals and non-leaf feeding insects including sucking insects like aphids, scale, or mealy bugs. Here’s a link to more information from Cornell University’s Resource Guide for Organic Insect and Disease Management.

Remember, just because a product is labeled “organic” doesn’t mean that is without risk. This is a product that can kill living creatures, albeit pests; use it only if you must and with care. The goal is always to keep the garden in balance so pull this trigger only when things are beginning to get out of control, not when you see a few ragged leaves. We need some of the bad bugs around so that the good bugs that eat them will stay in our gardens.

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Block Island, Rhode Island

Irvine, California


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We are deep into spring and on our way to summer though it sure doesn’t feel like it in Southern California. We’ve got cool temps, wind and rain which is unusual for this time of year. What’s not so unusual are the garden pests that have started to make their appearance in my garden and which will soon be plaguing Mary Beth and the rest of you in somewhat cooler zones. So we thought that for the next few weeks we’d look at organic ways to deal with the bugs and diseases that bother us in the garden.

We’d like to point out first of all that some nibbling of leaves, flowers and fruits is normal. Bugs are supposed to be in your garden. Live with it. Insects are part of the whole wonderful cycle that makes this all work. We are not striving for a bug-free zone, we are looking to create a balance in the garden. That said there are times when you need to get the upper hand especially when something is devouring your herbs or, perish the thought, your beautiful tomatoes.

This week we’ll be looking at Bt or Bacillus thuringiensis. The most commonly used form of Bt, the one you’ll likely see at your nursery, is Bacillus thuringiensis kurstaki. It is used for controlling leaf-eating caterpillars like cabbage worms and tomato hornworms (although they are called worms they are really caterpillars). Another form, Bacillus thuringiensis israelensis, is used to control certain fly larvae like mosquito larvae which can be a problem in ponds.

Here’s what Colorado State University Extension has to say about Bt:

“The most commonly used strain of Bt (kurstaki strain) will kill only leaf- and needle-feeding caterpillars. In the past decade, Bt strains have been developed that control certain types of fly larvae (israelensis strain, or Bti). These are widely used against larvae of mosquitoes, black flies and fungus gnats.

More recently, strains have been developed with activity against some leaf beetles, such as the Colorado potato beetle and elm leaf beetle (san diego strain, tenebrionis strain). Among the various Bt strains, insecticidal activity is specific. That is, Bt strains developed for mosquito larvae do not affect caterpillars. Development of Bt products is an active area and many manufacturers produce a variety of products. Effectiveness of the various formulations may differ.

Insects Controlled by Bt

Kurstaki strain (Bonide Thuricide, Safer Caterpillar Killer, Greenstep Caterpillar Control, etc):

  • Vegetable insects
    • Cabbage worm (cabbage looper, imported cabbageworm, diamondback moth, etc.)
    • Tomato and tobacco hornworm
  • Field and forage crop insects
    • European corn borer (granular formulations have given good control of first generation corn borers)
    • Alfalfa caterpillar, alfalfa webworm
  • Fruit crop insects
    • Leafroller
    • Achemon sphinx
  • Tree and shrub insects
    • Tent caterpillar
    • Fall webworm
    • Leafroller
    • Red-humped caterpillar
    • Spiny elm caterpillar
    • Western spruce budworm
    • Pine budworm
    • Pine butterfly

Israelensis strains (Vectobac, Mosquito Dunks, Gnatrol, Bactimos, etc.)

    • Mosquito
    • Black fly
    • Fungus gnat

San diego/tenebrionis strains (Trident, M-One, M-Trak, Foil, Novodor, etc.)

    • Colorado potato beetle
    • Elm leaf beetle
    • Cottonwood leaf beetle”
We (back to Bees and Chicks now) have used Bt for years and find it very effective and safe when used according to package directions. It is not harmful to humans, pets, or beneficial insects like bees. It can be used up to the day before harvest (I’d still want to wash sprayed fruit before eating).
Nonetheless, you shouldn’t go spraying everything willy-nilly. Be sure first of all that a caterpillar is what is eating your plant. Some insects that look like caterpillars are really worms, most notably rose slugs, and Bt will not kill worms. (Note that these are called slugs, but are really worms! For info on how to identify and control rose slugs click here.)  If it is a caterpillar eating your plants, spray just the affected plants/area. You must be very thourough because the caterpillar needs to eat the BT for it to be effective. You may need to repeat the application every 5 – 7 days while the insects are active. We have usually gotten good results with just a couple of sprays.
A note of caution here: Bt will kill good caterpillars as well as bad. If you have a butterfly garden or plants that attract butterflies, DO NOT spray when these caterpillars are feeding.
Bt is but one tool in the organic arsenal. Next week we will take a look at more.

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Block Island, Rhode Island

Irvine, California


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Block Island, Rhode Island

Irvine, California


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