Alright. I know that the title of this post is controversial for this website, but I’m serious about this. Read a little further and this might not seem so radical.
Over the last 40 years I have gardened in Denver, Davis California, Western Colorado, Delaware and in San Diego county. By far the most challenging place to garden has been in San Diego. We have no winter here to knock back the pest populations. We have lots of misty, cloudy days in May and June because we are only 2 miles from the ocean. It is pretty much of a pest and disease heaven. I am constantly fighting pest issues in my garden and vineyard here, and I often wish I had better tools to do that.
I still try to garden because that is a “local food” option that I believe in (tomatoes, zucchini, basil, hot peppers…). I also have a little vineyard (only 25 vines) that gives me about 15 gallons of wine per year. Even as an “expert” on grapes diseases, there are serious pest issues for the grapes that are problematic for me to control. I tried to do it with sulfur and insecticidal soap (things that would be allowed under Organic rules), but the results were dismal.
It is particularly frustrating for me because I work in agricultural technology and so I know all about the safe and effective pesticides that are available to real farmers. We homeowners are stuck with very old pesticide options that you can buy at the Home Depot or even at a high-end nursery.
For example, I wish I could buy Flint® fungicide. It is based on the active, trifloxystrobin and it would control both the powdery mildew and Botrytis bunch rot (pictured) that are problems for my little vineyard. It is essentially non-toxic to mammals. The measure of that is called a “rat Oral LD50” and it has a value of 5,050 mg/kg on a scale where bigger numbers are safer. Table salt has a value of 3,000 so you can see that Flint is pretty safe. The “pesticides” that would fit most people’s negative image are things like azinphos methyl, a 60+ year-old insecticide with a “rat LD50” of 7 mg/kg. That would be 700 times as toxic as Flint®. Azinphos methyl is only used today under extremely restrictive rules on a few crops. It is certainly not sold to homeowners.
The copper fungicide they sell at Home Depot and which is approved for organic has an LD50 of 472. That is not terrible, but it is a lot more toxic than the best, modern options and it is also much less effective against diseases. It also accumulates copper in the soil where it is sprayed. There is nothing particularly “green” about that option.
Another good option would be fludioxanil which is similarly non-toxic. In fact there is a product with both cyprodinil and fludioxanil called Switch® which would be even better.
I have been able to buy a product with a 20+year-old fungicide called myclobutanil (at least two generations of fungicides back from what is cutting edge today). It does a good job on the mildew, but not the Botrytis. It isn’t too bad from a toxicity point of view with a rat LD50 of 1,600 mg/kg.
These are just examples. There are a lot of other really safe options that would make my gardening and small-scale viticulture easier. Why aren’t these super safe options available for homeowners? There are several reasons:
- The consumer market will always be dominated by old, off-patent chemicals that are cheap. That is just the nature of consumer marketing
- Manufacturers of chemicals know that homeowners are the least responsible of all pesticide users (“a little is good, a lot is better”, “I’m done with this, I’ll dump it down the sink or the gutter”…) so they are reluctant to put their elite products in their hands
- Homeowners have little access to accurate information about pesticides and little patience to learn about them
Does it matter on the grand scale of things that my grapes rot or that my tomato vines die too soon? No, probably not. I just find it frustrating to know that I could solve these problems with really benign pesticide options that I can’t access.
Most people think that all pesticides are the same and that they are all “bad.” In fact they differ dramatically in all aspects of toxicity and environmental effects, and there are many that are really quite safe. No one seems to talk about this. Perhaps they should.
Grape Botrytis images by Steve Savage