"The tragic reality is that very few sustainable systems are designed or applied by those who hold power, and the reason for this is obvious and simple: to let people arrange their own food, energy and shelter is to lose economic and political control over them. We should cease to look to power structures, hierarchical systems, or governments to help us, and devise ways to help ourselves." - Bill Mollison

Saturday, June 20, 2009


Leafminers have become a substantial pest issue for us over the past couple of years causing damage to many of our leafy greens. Spinach, beet greens, tomatillo and ground cherry leaves, beetberry, French sorrel, and especially Swiss chard all seem to be the prime targets in our gardens.

Late spring spinach (note the outline of a worm in bottom corner)

Flat of Egypt beet greens

Swiss chard

The small gray flies lay their eggs in neat little clusters on the underside of the leaves.

As the maggots emerge they get in between the leaf tissue mining their way throughout the leaves as they feed.

The first of the many cycles they go through each year seem to be the most damaging for our crops and as the season progresses the damage inflicted becomes less noticeable. The only solution I have come up with to combat these little nasties is to pull off the tunnelled leaves and feed them to our ravenous chickens.

On a smaller scale one could attempt to destroy the egg clusters before they hatch but we grow too much chard for that to be a practical solution to the problem. I have noticed a huge number of parasitic wasps going after the maggots in the leaves but the pests still seem to outweigh the predators.

One thing I am going to do is allow the birds into the garden for a brief period this fall and the following spring to help combat any overwintering insects. If anyone has found an organic method of relieving themselves of these exasperation's please do tell.

"Too close a look can oft temper ones enthusiasm for a natural salad" - Mike :)


Silke said...

That's one way to get more protein in your diet...;) I don't know anything about leafminers except that they are extremely hard to get rid of. Good thing you do have wasps that eat some of the maggots. We haven't had them here yet in our tiny garden... :) Silke

Michelle said...

You could try spinosad. It's a treatment that is derived from a bacterium and works on many different chewing insects (approved for organic crops). Here's a link to Peaceful Valley (an organic farm and garden supply source online): http://www.groworganic.com/item_PBI800_Monterey_Garden_Spray_Concentrat.html

There are links there to the Material Safety Data Sheet and the product label so you can see if it is something you would want to use.

I've purchased this product from them and have used it when the damage from chewing insects just gets to be too out of control. It has worked on leafminers for me.

I'm not sure that your chickens would approve of the loss of their buggy snacks though :)

Stefaneener said...

Hmmm. Michelle's idea sounds interesting. I don't grow spinach much any more and hardly any beets -- the leafminers are just too bad. I know floating row covers are supposed to help, but in your case that's probably impractical because of the space. I may try it though -- I love spinach so much and otherwise it grows really well here.

Mr. H said...


Yes, I often wonder what extra protein we do ingest.:)

Mr. H said...


In our garden the problem becomes less of an issue later in the season. But yes, it makes one question growing certain crops... for me it is Swiss chard. I hope you try Michelle's spinosad, and it works, because no garden should be without beets, chard, or spinach.:)

Michelle said...

Mr H, I will be very interested to know how it works for you. Glad to help!

eag said...

Well nothing like hens or geese to do a great job of these things.

Mr. H said...


The birds are a wonderful addition to our garden area. They are able to range around 3/4 of the garden perimeter and the one side they do not have access to is the only place we still have issues with voles (mice like monsters that eat my garden veggies

Mr. H. said...


I just looked it up and it sounds interesting.

From Wikipedia: Spinosad - The active ingredient is derived from a naturally occurring soil dwelling bacterium called Saccharopolyspora spinosa, a rare actinomycete reportedly collected from soil in an abandoned rum distillery on a Caribbean Island in 1982 by a scientist on vacation. It has not been found in nature since that time, and was subsequently described as a new species.

Spinosad has since been formulated into insecticides that combine the efficacy of a synthetic insecticide with the benefits of a biological pest control organism.

It is used to control a variety of insect pests, including fruit flies, caterpillars, LEAFMINERS, thrips, sawflies, spider mites, fire ants, and leaf beetle larvae.

Spinosad is recommended for use in an Integrated Pest Management program for commercial greenhouses since it will not harm most beneficial insects or predatory mites.

Spinosad does not significantly affect beneficial organisms including ladybugs, green lacewings, minute pirate bugs, and predatory mites.

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